JP2020073736A - Metal part manufacturing process and heat treatment apparatus - Google Patents

Abstract

To provide a heat treatment apparatus in which, with respect to a metallic workpiece, the distortion due to heat treatment can be further reduced as well as a heat treatment time of the workpiece can be shortened.SOLUTION: In the heat treatment apparatus, a metallic workpiece 100 formed in an annular shape and a heater unit 6 radiating heat toward a predetermined main radiation direction D2 are opposed to each other. Further, the workpiece 100 is arranged so that the inferior angle θ1 between the axial direction D1 of the workpiece 100 and the main radiation direction D2 is 45° or less (including zero). The workpiece 100 is heated by using the heater unit 6.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a metal part and a heat treatment apparatus.

  A configuration is known in which a heat treatment is applied to a steel ring member by a heating device, and then the ring member is cooled to heat-treat the ring member (see, for example, Patent Document 1).

JP, 2007-297664, A

  At the time of heat treatment of the ring member, it is required to reduce strain (for example, thermal strain) in the ring member as much as possible. For example, ring members used in high-load environments, such as the inner and outer rings of tapered roller bearings, have been subjected to heat treatment such as carburizing and quenching. However, in this heat treatment, so-called elliptic distortion occurs, which distorts the circularity of the ring member. Elliptic strain refers to a phenomenon in which a perfectly circular steel component is distorted into an elliptical shape. In order to correct such an elliptic distortion, for example, a multistage construction method is employed in which the ring member is hardened by heating and then turned, which is inefficient.

  Further, when the heat treatment of the ring member is performed, the temperature difference between the respective portions of the ring member can be suppressed by grading the temperature change, so that the strain can be suppressed. However, in this case, the heat treatment of the ring member takes time. Such a problem of strain and a problem of time required for heat treatment are not limited to ring members, and also exist in various metal components to be heat treated such as plate-shaped components.

  In view of the above circumstances, the present invention provides a method for manufacturing a metal component and a heat treatment apparatus capable of further reducing strain due to heat treatment and further shortening the heat treatment time of an object to be treated. To aim.

  Conventionally, in order to suppress the distortion of the object to be processed during the heat treatment, it has been common to focus on the cooling step after heating the object and devise the cooling step to suppress the distortion. On the other hand, the inventor of the present application paid attention to the temperature raising step (temperature raising step) of the object to be treated, and further conceived a method of arranging the object to be treated in the temperature raising step which has not been found in the past. As a result, it has become possible to significantly reduce the elliptic strain of the object to be treated during the heat treatment.

  (1) A method for manufacturing a metal component according to an aspect of the present invention based on the above-mentioned findings provides a metal workpiece having an annular portion as a portion including at least a part of the annular shape, and the workpiece. A heat source arranged outside the object to be processed and a heat source that radiates heat in a predetermined main radiation direction are opposed to each other, and an inferior angle formed by the axial direction of the annular portion and the main radiation direction is 45 °. The arrangement step of arranging the object to be treated as follows (including zero), and the heating step of heating the object to be treated using the heat source, in the arrangement step, the object to be treated is , Is arranged between a plurality of heating units provided in the heat source, and is arranged in an upright posture, and the axial direction is along the horizontal direction or the axial direction is inclined with respect to the horizontal direction. In the direction .

  With this configuration, the heat from the heat source is more evenly transferred to each part of the object to be processed. This makes it possible to further reduce the temperature difference inside the object to be processed when the object to be processed is heated by the heat source. More specifically, the temperature difference of the annular portion in the circumferential direction of the annular portion can be made smaller. In particular, when the axial direction coincides with the main radiation direction, that is, when the inferior angle is zero, the temperature difference in the object to be processed in the circumferential direction of the annular portion can be significantly reduced. In addition, since the object to be processed is arranged in an upright posture between the plurality of heating parts, the inside of the object to be processed can be heated more evenly in the direction in which the plurality of heating parts face each other. The difference can be made even smaller. As a result, it is possible to suppress the occurrence of stress imbalance in the object to be processed. For example, the timing at which each part undergoes austenite transformation can be made more uniform within one object. Furthermore, as a result of suppressing the occurrence of stress imbalance in the object to be processed, the object to be processed can be heat-treated in a shorter time. As a result, it is possible to further reduce the strain caused by the heat treatment on the metal object to be processed and further shorten the heat treatment time of the object to be processed. More specifically, the elliptic distortion in which the object to be processed is distorted in an elliptical shape can be further reduced. For example, when the object to be processed is heated to the A1 transformation point or higher, the timing at which the temperature of each part in the object passes the A1 transformation point can be made more uniform. As a result, it is possible to suppress the occurrence of transformation stress in the object to be processed. Further, when the axial direction is along the horizontal direction, it is possible to suppress the tensile stress from being generated in the object to be processed. Thereby, the strain caused by the stress of the object to be processed can be significantly reduced. Further, when the axial direction is a direction inclined with respect to the horizontal direction, it is possible to more appropriately arrange the plurality of objects to be processed in consideration of the weight balance of the plurality of objects to be processed as a whole.

  (2) A method for manufacturing a metal component according to an aspect of the present invention based on the above-mentioned findings is a plate-shaped metal object to be processed having a predetermined thickness, and a heat source arranged outside the object to be processed. And a heat source that radiates heat in a predetermined main radiation direction faces each other, and an inferior angle formed by the thickness direction of the object to be processed and the main radiation direction is 45 ° or less (including zero). So as to arrange the object to be processed, and a heating step of heating the object to be processed using the heat source, in the arrangement step, the object to be processed is a plurality of provided in the heat source. It is arranged between the heating parts of the above, and is arranged in an upright posture, and the thickness direction is along the horizontal direction or the thickness direction is a direction inclined with respect to the horizontal direction.

  With this configuration, the heat from the heat source is more evenly transferred to each part of the object to be processed. This makes it possible to further reduce the temperature difference inside the object to be processed when the object to be processed is heated by the heat source. More specifically, the temperature difference of the object to be processed, for example, in the circumferential direction of the outer peripheral edge portion can be further reduced. In particular, when the thickness direction and the main radiation direction coincide with each other, that is, when the inferior angle is zero, the temperature difference in the object to be processed in the circumferential direction can be remarkably reduced. In addition, since the object to be processed is arranged in an upright posture between the plurality of heating parts, the inside of the object to be processed can be heated more evenly in the direction in which the plurality of heating parts face each other. The difference can be made even smaller. As a result, it is possible to suppress the occurrence of stress imbalance in the object to be processed. For example, the timing at which each part undergoes austenite transformation can be made more uniform within one object. Furthermore, as a result of suppressing the occurrence of stress imbalance in the object to be processed, the object to be processed can be heat-treated in a shorter time. As a result, it is possible to further reduce the strain caused by the heat treatment on the metal object to be processed and further shorten the heat treatment time of the object to be processed. For example, the elliptic distortion in which the object to be processed is distorted in an elliptical shape can be further reduced. For example, when the object to be processed is heated to the A1 transformation point or higher, the timing at which the temperature of each part in the object passes the A1 transformation point can be made more uniform. As a result, it is possible to suppress the occurrence of transformation stress in the object to be processed. Further, when the thickness direction is along the horizontal direction, it is possible to suppress the tensile stress from being generated in the object to be processed. Thereby, the strain caused by the stress of the object to be processed can be significantly reduced. Further, when the thickness direction is a direction inclined with respect to the horizontal direction, the plurality of objects to be processed can be more appropriately arranged in consideration of the weight balance of the plurality of objects to be processed as a whole.

  (3) In the arranging step, the plurality of objects to be processed may be arrayed along the main radiation direction.

  With this configuration, it is possible to collectively heat-treat a plurality of objects to be processed while reducing the strain.

  (4) In the arranging step, a predetermined holder may support the outer peripheral surface of the object to be processed from below.

  With this configuration, it is possible to suppress the occurrence of tensile stress in the object to be processed. Thereby, the strain caused by the stress of the object to be processed can be significantly reduced.

  (5) The holder may support the object in line contact or point contact.

  According to this configuration, the holder can support the object to be processed in a state in which the expansion and contraction of the object to be processed during the heat treatment of the object to be processed are suppressed. As a result, the strain of the object to be processed due to the heat treatment can be further reduced.

  (6) The holder supports the outer peripheral surface of the object to be processed by a first support portion and a second support portion that are separated from each other in the circumferential direction of the outer peripheral surface, and the holder is provided around the central axis of the object to be processed. The angular interval between the first support portion and the second support portion may be set in the range of 20 ° to 60 °.

  According to this configuration, by setting the angle range between the first support portion and the second support portion to 20 ° or more, the stress acting on each part of the object to be processed supported by these support portions can be made more uniform. .. Therefore, distortion of the object to be processed can be further reduced. Further, by setting the angle range between the first support portion and the second support portion to be 60 ° or less, when the object to be processed thermally expands by heat treatment, the object to be processed is sandwiched between the two support parts due to expansion. Can be suppressed. Accordingly, it is possible to prevent the object to be processed from being deformed so as to bite into the two support portions.

  (7) In the heating step, the object to be processed may be heated in an atmosphere gas set to a carbon potential of 0.6% to 1.0%.

  According to this configuration, when heating the object to be processed, the time required for each part of the surface of the object to be processed to shift from the area of ferrite + cementite to the area of austenite can be further shortened. As a result, the object to be treated can be transformed into austenite more uniformly.

  (8) The heating step may be performed at least between the A1 transformation point and the A3 transformation point of the workpiece.

  According to this configuration, each part of the object to be processed can undergo austenite transformation more uniformly.

  (9) In the heating step, the object to be processed may be heated from the A1 transformation point to the A3 transformation point at a temperature rising rate in the range of 0.5 ° C / min to 10 ° C / min.

  According to this configuration, since the temperature rising rate (temperature rising rate) of the object to be processed is equal to or higher than the above lower limit value, the time required for transforming the object to be processed from the A1 transformation point to the A3 transformation point is further reduced. Can be shortened. In addition, since the temperature rising rate of the object to be processed is equal to or lower than the above upper limit value, when the object to be processed is transformed from the A1 transformation point to the A3 transformation point, the outer surface of the object to be treated and the interior of the object to be treated It is possible to sufficiently reduce the temperature difference between the outer surface and the inside of the object to be processed when heat is transferred. Thereby, the transformation stress inside the object to be treated can be further reduced. Therefore, distortion of the object to be processed can be further reduced. In other words, when each part of the object to be processed undergoes austenite transformation, the unevenness of transformation timing (that is, nonuniformity of transformation timing) can be further reduced.

  (10) The object to be processed may have a tubular shape extending in the axial direction of the object to be processed, and the shape in a cross section orthogonal to the axial direction may be polygonal.

  According to this structure, the degree of temperature change of each part can be made more uniform in the processing object formed in a polygonal ring shape. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  (11) The object to be processed may be formed in a ring shape.

  According to this configuration, the degree of temperature change of each part can be made more uniform in the ring-shaped object to be processed. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  (12) The object to be processed may have an inner peripheral part formed in a shape similar to the shape of the outer peripheral part of the object to be processed.

  With this configuration, for example, in the object to be processed that is formed in an annular shape and has a substantially uniform thickness, the degree of temperature change in each part can be made more uniform. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  The object to be processed may include a race or a gear of a bearing.

  With this configuration, it is possible to manufacture a bearing or a gear with high dimensional accuracy.

  (13) A plurality of holes may be formed in the object to be processed.

  With this configuration, for example, in the object to be processed in which a plurality of holes are formed, such as a link plate of a chain, the degree of temperature change of each part including the peripheral portions of the plurality of holes can be made more uniform. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  (14) A blade may be formed on the outer peripheral portion of the object to be processed.

  According to this configuration, in the object to be processed having the blade portion formed on the outer peripheral portion, such as a cutter blade used for an engine cutter, the degree of temperature change of each portion including the outer peripheral portion can be made more uniform. As a result, it is possible to form a metal part having a small distortion.

  (15) Further, a heat treatment apparatus according to an aspect of the present invention includes a heat source having a plurality of heating units and configured to radiate heat in a predetermined main radiation direction, and at least a part of a ring shape. And a heat source made of a metal having an annular portion as a portion including the heat source are opposed to each other so that the heat source is arranged outside the treatment object, and the treatment object has a plurality of heating portions. A holder for arranging the object to be processed such that an inferior angle formed by the axial direction of the annular portion and the main radiation direction is 45 ° or less (including zero) in a state of being arranged between The holder is configured to support the object to be processed in an upright posture, and the axial direction is along the horizontal direction or the axial direction is inclined with respect to the horizontal direction. Supports the object It is configured.

  With this configuration, the heat from the heat source is more evenly transferred to each part of the object to be processed. This makes it possible to further reduce the temperature difference inside the object to be processed when the object to be processed is heated by the heat source. More specifically, the temperature difference of the annular portion in the circumferential direction of the annular portion can be made smaller. In particular, when the axial direction coincides with the main radiation direction, that is, when the inferior angle is zero, the temperature difference in the object to be processed in the circumferential direction of the annular portion can be significantly reduced. In addition, since the object to be processed is arranged in an upright posture between the plurality of heating parts, the inside of the object to be processed can be heated more evenly in the direction in which the plurality of heating parts face each other. The difference can be made even smaller. As a result, it is possible to suppress the occurrence of stress imbalance in the object to be processed. For example, the timing at which each part undergoes austenite transformation can be made more uniform within one object. Furthermore, as a result of suppressing the occurrence of stress imbalance in the object to be processed, the object to be processed can be heat-treated in a shorter time. As a result, it is possible to further reduce the strain caused by the heat treatment on the metal object to be processed and further shorten the heat treatment time of the object to be processed. More specifically, the elliptic distortion in which the object to be processed is distorted in an elliptical shape can be further reduced. For example, when the object to be processed is heated to the A1 transformation point or higher, the timing at which the temperature of each part in the object passes the A1 transformation point can be made more uniform. As a result, it is possible to suppress the occurrence of transformation stress in the object to be processed. Further, when the axial direction is along the horizontal direction, it is possible to suppress the tensile stress from being generated in the object to be processed. Thereby, the strain caused by the stress of the object to be processed can be significantly reduced. Further, when the axial direction is a direction inclined with respect to the horizontal direction, it is possible to more appropriately arrange the plurality of objects to be processed in consideration of the weight balance of the plurality of objects to be processed as a whole.

  (16) Further, a heat treatment apparatus according to an aspect of the present invention includes a heat source having a plurality of heating units and configured to radiate heat directed in a predetermined main radiation direction, and a plate-like member having a predetermined thickness. The object to be processed and the heat source made of metal are opposed to each other so that the heat source is arranged outside the object to be processed, and the object to be processed is arranged between the plurality of heating units. A holder for arranging the object to be processed such that an inferior angle formed by the thickness direction of the object to be processed and the main radiation direction is 45 ° or less (including zero); It is configured to support the object to be processed in an upright posture, and to support the object to be processed such that the thickness direction is along the horizontal direction or the thickness direction is inclined with respect to the horizontal direction. Is configured.

  With this configuration, the heat from the heat source is more evenly transferred to each part of the object to be processed. This makes it possible to further reduce the temperature difference inside the object to be processed when the object to be processed is heated by the heat source. More specifically, the temperature difference of the object to be processed, for example, in the circumferential direction of the outer peripheral edge portion can be further reduced. In particular, when the thickness direction and the main radiation direction coincide with each other, that is, when the inferior angle is zero, the temperature difference in the object to be processed in the circumferential direction can be remarkably reduced. In addition, since the object to be processed is arranged in an upright posture between the plurality of heating parts, the inside of the object to be processed can be heated more evenly in the direction in which the plurality of heating parts face each other. The difference can be made even smaller. As a result, it is possible to suppress the occurrence of stress imbalance in the object to be processed. For example, the timing at which each part undergoes austenite transformation can be made more uniform within one object. Furthermore, as a result of suppressing the occurrence of stress imbalance in the object to be processed, the object to be processed can be heat-treated in a shorter time. As a result, it is possible to further reduce the strain caused by the heat treatment on the metal object to be processed and further shorten the heat treatment time of the object to be processed. For example, the elliptic distortion in which the object to be processed is distorted in an elliptical shape can be further reduced. For example, when the object to be processed is heated to the A1 transformation point or higher, the timing at which the temperature of each part in the object passes the A1 transformation point can be made more uniform. As a result, it is possible to suppress the occurrence of transformation stress in the object to be processed. Further, when the thickness direction is along the horizontal direction, it is possible to suppress the tensile stress from being generated in the object to be processed. Thereby, the strain caused by the stress of the object to be processed can be significantly reduced. Further, when the thickness direction is a direction inclined with respect to the horizontal direction, the plurality of objects to be processed can be more appropriately arranged in consideration of the weight balance of the plurality of objects to be processed as a whole.

  According to the present invention, it is possible to further reduce the strain due to heat treatment on the object to be treated made of metal, and to shorten the heat treatment time of the object to be treated.

FIG. 3 is a schematic cross-sectional view of the heat treatment apparatus according to the embodiment of the present invention, showing a state in which the heat treatment apparatus is viewed in a plan view. FIG. 3 is a schematic cross-sectional view of the heat treatment apparatus, showing a state in which the heat treatment apparatus is viewed from the side. It is the figure which expanded the holder and to-be-processed object in the heat processing apparatus of FIG. It is the figure which expanded the holder and to-be-processed object in the heat processing apparatus of FIG. It is a schematic diagram for demonstrating the relationship between a holder and a to-be-processed object. It is a schematic diagram for explaining the inferior angle, and shows the case where the inferior angle is not zero. It is a flow chart for explaining an example of heat treatment operation in a heat treatment device. It is a graph which shows an example of temperature control of the to-be-processed object in a heat processing apparatus. FIG. 3 is a schematic equilibrium state diagram of a Fe—C alloy for explaining the state of the object to be heat treated by the heat treatment apparatus. It is a typical top view of a holder and a heater unit with which a heat treatment equipment concerning a 2nd embodiment of the present invention is equipped. FIG. 3 is a schematic side view of a main part showing a holder and an object to be processed held by the holder. FIG. 3 is a schematic front view of a main part showing a holder and an object to be processed held by the holder. It is a schematic plan view of the principal part which shows the holder with which the heat treatment apparatus which concerns on 2nd Embodiment of this invention is equipped, and the to-be-processed object hold | maintained at the said holder. It is a typical side view of the principal part for demonstrating one of the modifications. FIG. 15 is a schematic side view of a main part for explaining a modification different from the modification shown in FIG. 14. It is a top view for explaining other examples of a processed object, and is a figure which expanded a holder and a processed object in a heat treatment equipment. It is sectional drawing which looked at the to-be-processed object from the front, and also has shown some holders. It is sectional drawing of a holder and a to-be-processed object, and has shown the state which looked at the to-be-processed object from the side. FIG. 6 is a schematic plan view of a main part showing a holder provided in a heat treatment apparatus according to another example of the present invention and an object to be processed held by the holder. It is a typical side view of the principal part for demonstrating one of the modifications related to the modification shown in Drawing 16A-Drawing 16D. FIG. 17C is a schematic side view of a main portion for describing a modification different from the modification shown in FIG. 16E. It is a typical perspective view of another to-be-processed object. FIG. 11 is a front view for explaining still another example of the object to be processed, which is a cross-sectional view, and shows an enlarged main part of the holder and the object to be processed in the heat treatment apparatus. It is a top view for explaining other examples of a processed object, and is showing a holder and four kinds of processed objects in a heat treatment device on an enlarged scale. It is sectional drawing which looked at 4 types of to-be-processed objects from the front, and also shows a part which hold | maintains to-be-processed object using a convex part also in a part of holder. It is sectional drawing which looked at 4 types of to-be-processed objects from the front, and also shows a part which holds the to-be-processed object with a recessed part also in a part of holder. FIG. 3 is a schematic plan view of a main part showing a holder provided in the heat treatment apparatus and four types of objects to be processed held by the holder. It is a typical side view of the principal part for demonstrating one of the modifications related to the modification shown in Drawing 19A-Drawing 19D. It is a typical side view of the principal part for demonstrating the modification different from the modification shown in FIG. 19E. It is a graph for demonstrating the distortion according to the kind of placement of a to-be-processed object. It is a graph for explaining the relationship between the inferior angle formed by the axial direction of the object to be processed and the main radiation direction, and the strain. It is a graph for explaining the relationship between the carbon potential of the furnace atmosphere and strain.

  Embodiments for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a heat treatment apparatus 1 according to an embodiment of the present invention, showing a state in which the heat treatment apparatus 1 is viewed in a plan view. FIG. 2 is a schematic cross-sectional view of the heat treatment apparatus 1, showing the heat treatment apparatus 1 in a side view. FIG. 3 is an enlarged view of the holder 2 and the object 100 to be processed in the heat treatment apparatus 1 of FIG. FIG. 4 is an enlarged view of the holder 2 and the object 100 to be processed in the heat treatment apparatus 1 of FIG. In FIG. 4, a part of the object to be processed 100 is not shown.

  Referring to FIGS. 1 and 2, heat treatment apparatus 1 is provided for heat treating object 100 to be processed. Examples of this heat treatment include carburizing treatment such as vacuum carburizing, carbonitriding, and carburizing and quenching, quenching treatment, tempering treatment, and annealing treatment. In the present embodiment, a case where the heat treatment apparatus 1 is a gas carburizing treatment furnace will be described as an example.

  The object to be processed 100 is a metal member formed in a circular shape. The “circular shape” in this case includes a cylindrical shape having a through hole formed therein, a disk shape having no through hole formed therein, a shape in which the envelope of the outer shape is circular, and the like. An example of the member having a circular outer shape envelope is a gear having teeth formed on its outer peripheral portion. Further, the object to be processed 100 has an annular portion as a portion including the shape of at least a part of the annular portion. Examples of the "annular portion" in this case include an annular portion, a polygonal annular portion, and a peripheral portion of the hole portion in the portion where the hole portion is formed. In the present embodiment, the object to be processed 100 is provided as a portion including the entire annular portion.

  In the present embodiment, the object to be processed 100 is a ring-shaped metal part. The processing object 100 is also a plate-shaped processing object made of metal having a predetermined thickness TH1. In the present embodiment, the thickness direction D3 of the object 100 to be processed is the same as or parallel to the axial direction D1 of the object 100 to be processed. The object to be processed 100 is formed in a substantially circular cylinder shape, and the strain amount is substantially zero in the state before the heat treatment by the heat treatment apparatus 1 is performed. The strain in this case means, for example, elliptic strain, and means a difference or a ratio between a portion having the largest diameter and a portion having the smallest diameter in the object to be treated 100.

  Both the inner peripheral portion and the outer peripheral portion of the object to be processed 100 are formed in a circular shape in a cross section orthogonal to the axial direction D1 of the object to be processed 100. With this configuration, the shape of the outer peripheral portion and the shape of the inner peripheral portion of the object to be processed 100 are similar to each other.

  Examples of the object 100 to be processed include race members such as outer and inner rings of rolling bearings, gears such as spur gears, rollers of rolling bearings, shafts and washers. It should be noted that the object to be processed 100 of the present embodiment may be any metal part that is formed in a circular shape and is heat-treated. The workpiece 100 is, for example, carbon steel having a carbon content (carbon potential) of about 0.2%. The carbon content of the object 100 to be processed may be 0.15% to 0.2%. In the present embodiment, the object to be processed 100 is formed in a ring shape having a thickness TH1 of about several mm in the axial direction D1 of the object to be processed 100. Therefore, the inner peripheral surface and the outer peripheral surface of the object to be processed 100 are cylindrical shapes concentric with each other.

  The heat treatment apparatus 1 has a heat treatment unit 3 and a control unit 4.

  The heat treatment unit 3 includes a holder 2, a heat treatment furnace 5, a heater unit 6, a pedestal 7, a stirrer 8, and an atmosphere gas supply unit 9.

  The heat treatment furnace 5 is formed in a hollow box shape. The heat treatment furnace 5 forms an accommodation chamber for accommodating the object 100 to be processed. An inlet door 10 and an outlet door 11 are formed on a pair of side walls of the heat treatment furnace 5 which face each other and are arranged substantially parallel to each other. The object 100 to be processed is carried into the heat treatment furnace 5 from the outside of the heat treatment furnace 5 with the entrance door 10 opened. Further, the workpiece 100 is carried out of the heat treatment furnace 5 to the outside of the heat treatment furnace 5 with the outlet door 11 opened. Further, the inlet door 10 and the outlet door 11 are closed while the workpiece 100 is being heat-treated. In this embodiment, the direction from the entrance door 10 to the exit door 11 is defined as the traveling direction X1.

  The heat treatment furnace 5 is provided with a temperature sensor 12 for detecting the furnace temperature T as the temperature in the heat treatment furnace 5. The temperature detection result of the temperature sensor 12 is given to the control unit 4. Further, the heat treatment furnace 5 is provided with an oxygen sensor 13 for measuring the carbon potential in the heat treatment furnace 5. The detection result of the oxygen concentration by the oxygen sensor 13 is given to the control unit 4. A heater unit 6 is arranged in the heat treatment furnace 5.

  The heater unit 6 is provided to raise the temperature in the heat treatment furnace 5 to a temperature required for heat treatment of the object 100 to be processed. The heater unit 6 is arranged in the heat treatment furnace 5 along the traveling direction X1. The heater unit 6 is arranged at a position apart from each of the four side walls of the heat treatment furnace 5 in a plan view.

  The heater unit 6 has a plurality of first heaters 14 and a plurality of second heaters 15.

  Each of the heaters 14 and 15 has a heating element (electric heating element) configured to convert electric power supplied from a power source (not shown) into heat. Each of the heaters 14 and 15 is configured to heat the atmosphere in the heat treatment furnace 5 by performing a heating operation by the heating element. A plurality of first heaters 14 (six in the present embodiment) are arranged at substantially equal intervals along the traveling direction X1. Similarly, the plurality of second heaters 15 are arranged at substantially equal intervals along the traveling direction X1. In the present embodiment, the number of first heaters 14 and the number of second heaters 15 are set to be the same.

  Further, in the traveling direction X1, the position of each first heater 14 is aligned with the position of one corresponding second heater 15. Accordingly, the pair of first heater 14 and second heater 15 whose positions in the traveling direction X1 are aligned face each other in a state of being separated in a direction orthogonal to the traveling direction X1 in a plan view.

  The first heater 14 and the second heater 15 have the same configuration. More specifically, the first heater 14 and the second heater 15 are formed in the same shape and have the same heating performance.

  Each heater 14 and 15 has a tube 16 as a heating unit.

  The tube 16 is provided to transfer the heat generated by energizing the electric heating element arranged in the tube 16 to the space inside the heat treatment furnace 5. The heat treatment furnace 5 is heated by the heat generated from the electric heating element in the tube 16, and the object to be treated 100 in the heat treatment furnace 5 is heated. The tube 16 is formed in a cylindrical shape extending downward from the top wall 5a of the heat treatment furnace 5 in the heat treatment furnace 5, and has a vertically straight shape. The diameter of each tube 16 is set to a predetermined value. Each tube 16 extends from the top wall 5 a of the heat treatment furnace 5 to a position below the position of the upper surface of the pedestal 7. Each tube 16 radiates heat radially to the circumference of the tube 16.

  The main radiation direction D2 is defined in the heater unit 6 having the above configuration. The main radiation direction D2 is the direction in which the amount of heat supplied from the heater unit 6 per unit time is the largest. In other words, the heater unit 6 is configured to radiate the heat in the main radiation direction D2. In the present embodiment, the main radiation direction D2 is a direction in which the pair of heaters 14 and 15 having the same position in the traveling direction X1 face each other. More specifically, the main radiation direction D2 is a direction orthogonal to the traveling direction X1 in a plan view. In this embodiment, the heater unit 6 radiates heat in the direction orthogonal to the traveling direction X1. Further, in the present embodiment, the main radiation direction D2 is along the horizontal direction. It can be said that the main radiation direction D2 is the direction in which the combined value of each vector is the maximum when the amount of heat radiation from each heater 14 and 15 is displayed as a vector. When the heater as the heat source is only one heater 14 or one heater 15, the main radiation direction D2 is the direction in which the normal line at any point of the cylindrical portion of the tube 16 extends, and It can also be defined as a direction passing through the center point of the processing object 100.

  The pedestal 7 is arranged between the heaters 14 and 15 having the above configuration. The pedestal 7 is provided to support the holder 2. The pedestal 7 is, for example, arranged between the second heater 14 and 15 from the entrance door 10 in the traveling direction X1, and is also arranged between the fifth heaters 14 and 15 from the entrance door 10. The pedestal 7 includes, for example, a plurality of columns 7a to 7f. Each of the columns 7a to 7f extends vertically. For example, six columns 7a to 7f are provided, and four columns 7a, 7b, 7e, and 7f support the four corners of the holder 2, and two columns 7c and 7d support the middle portion of the holder 2. Is configured to.

  In the present embodiment, the three columns 7a, 7c, 7e are arranged between the second heaters 14 and 15 from the entrance door 10 in the traveling direction X1, and these three columns 7a, 7c, 7e emit the main radiation. They are arranged at equal intervals in the direction D2. Further, two of these three columns 7a, 7c, 7e are adjacent to the corresponding heaters 14, 15. Further, the remaining three columns 7b, 7d, 7f are arranged between the fifth heaters 14, 15 from the entrance door 10, and these three columns 7b, 7d, 7f are equally spaced in the main radiation direction D2. It is located in. Further, two of these three columns 7b, 7d, 7f are adjacent to the corresponding heaters 14, 15.

  The holder 2 is used to carry in and carry out one or more objects 100 to be processed into the heat treatment furnace 5. Further, the holder 2 is used to hold the object to be processed 100 when the object to be processed 100 is heat-treated. The holder 2 is made of metal in the present embodiment. The holder 2 is formed in a rectangular box shape whose upper part is open. The four side surfaces and one bottom surface of the holder 2 are formed in a mesh shape so that a fluid such as gas can pass therethrough.

  FIG. 5 is a schematic diagram for explaining the relationship between the holder 2 and the object 100 to be processed. 1 to 5, the holder 2 has a bottom frame portion 21, four vertical frame portions 22 to 25, and a receiving portion 26 attached to the bottom frame portion 21.

  The bottom frame portion 21 is formed, for example, by combining metal rods in a rectangular shape. Four vertical frame portions 22 to 25 extend from the four side portions of the bottom frame portion 21.

  The vertical frame portions 22 and 23 are formed as a pair of frame portions that are arranged so as to sandwich the object 100 to be processed in the front and rear (main radiation direction D2). The vertical frame portions 22 and 23 extend upward from both ends of the bottom frame portion 21 in the predetermined first arrangement direction E1 and are arranged so as to sandwich the plurality of workpieces 100 held by the receiving portion 26. ing. The vertical frame portion 22 is provided as a front frame portion and is arranged, for example, so as to be adjacent to the heater 14. The vertical frame portion 22 is provided as a rear frame portion and is arranged, for example, so as to be adjacent to the heater 15.

  The vertical frame portions 24 and 25 are formed as a pair of frame portions that are arranged so as to sandwich the object 100 to be processed on the left and right sides (the traveling direction X1). The vertical frame portion 24 is provided as a left frame portion, and the vertical frame portion 25 is provided as a right frame portion. The vertical frame portions 24 and 25 are arranged between the heaters 14 and 15 so that, for example, the heaters 14 and 15 extend in the facing direction.

  Each of the vertical frame portions 22 to 25 is formed in a mesh shape, and is configured to pass gas. It can be said that each of the vertical frame portions 22 to 25 is formed in a shape through which gas can pass by forming the opening portion. In the bottom frame portion 21 supporting the vertical frame portions 22 to 25, the receiving portion 26 extends between two side portions separated in the main radiation direction D2 described later.

  The receiving portion 26 is provided to support the plurality of objects to be processed 100. The receiving portion 26 extends along the predetermined first arrangement direction E1. The first arrangement direction E1 is along the axial direction D1 of the object 100 to be processed held by the receiving portion 26. Further, the first arranging direction E1 is along the direction in which the vertical frame portions 24 and 25 extend in a plan view. The receiving portion 26 has a plurality of supporting members 27.

  The support members 27 are arranged in a pair at a predetermined pitch along a second arrangement direction E2 that is orthogonal to the first arrangement direction E1 in plan view. Then, a plurality of pairs of support members 27, 27 are provided along the second arrangement direction E2. In the present embodiment, both the first arrangement direction E1 and the second arrangement direction E2 are substantially horizontal directions, and the inclination angle with respect to the horizontal plane is set to about 0 to several degrees. Then, the pair of adjacent support members 27, 27 supports the object to be processed 100.

  The pair of support members 27, 27 is configured to arrange the object 100 to be processed in the heat treatment furnace 5 in an upright posture. The axial direction D1 of the object 100 to be processed is along the horizontal direction. In this case, “along the horizontal direction” can be exemplified as an angle formed by the axial direction D1 and the horizontal plane being in the range of zero degrees to several degrees. In addition, in the present embodiment, the pair of support members 27, 27 supports the outer peripheral surface 100a of the object 100 to be processed from below the outer peripheral surface 100a to support the object 100 to be processed.

  Further, the pair of support members 27, 27 is configured to support the workpiece 100 at two points. More specifically, the pair of support members 27, 27 is configured to support the object 100 to be processed at two points in the circumferential direction of the object 100 to be processed. In this way, the pair of support members 27, 27 includes the outer peripheral surface 100a of the object to be processed 100, which is separated from the outer peripheral surface 100a in the circumferential direction of the outer peripheral surface 100a. It is configured to be supported by the two support portions 32).

  Each support member 27 is formed by using, for example, a metal rod having a circular cross section, and in the present embodiment, extends in parallel to the main radiation direction D2. In the present embodiment, each support member 27 extends in the first arranging direction E1 so as to come into linear contact with the object 100 to be processed and support the object 100 to be processed.

  More specifically, each support member 27 has a facing surface 28 that faces the workpiece 100 to be supported. The facing surface 28 extends straight along the first alignment direction E1. The portion of the facing surface 28 that is in contact with the object 100 to be processed forms the support portion 31 or the support portion 32. Thus, the first support portion 31 formed on one support member 27 of the pair of support portions 27, 27 and the second support portion 32 formed on the other support member 27 are present. Becomes In the present embodiment, the first support portion 31 and the second support portion 32 are linear portions extending in the first alignment direction E1 (main radiation direction D2). The outer peripheral surface 100a of the object to be processed 100 is supported by supporting portions 31 and 32 which are spaced apart from each other in the circumferential direction of the outer peripheral surface 100a.

  Further, the object 100 to be processed is placed in the holder 2 so that the subordinary angle θ1 formed by the axial direction D1 (that is, the thickness direction D3) of the object 100 to be processed and the main radiation direction D2 is 45 ° or less (including zero). Are arranged.

  FIG. 6 is a schematic diagram for explaining the inferior angle θ1 and shows a case where the inferior angle θ1 is not zero. 1 to 4 show a case where the inferior angle θ1 is zero. With reference to FIG. 6, in this embodiment, the inferior angle θ1 is defined as follows, for example. The inferior angle θ1 is defined by a plane including two straight lines, that is, a central axis B3 of the object to be processed 100 extending in the axial direction D1 and a reference line B4 extending along the main radiation direction D2, that is, a plane shown in FIG. 6. .. The inferior angle θ1 has a first half line B5 which is a part of the central axis line B3 and a second half line B6 which is a part of the reference line B4 with the intersection point where these two lines B3 and B4 intersect as the origin O. The smaller one of the two conjugate angles formed.

  The inferior angle θ1 may be defined by using an angle formed by a virtual orthogonal plane orthogonal to the reference line B4 (main radiation direction D2) and the central axis B3 (axial direction D1). In this case, the inferior angle θ1 when the virtual orthogonal plane is orthogonal to the central axis B3 is zero. Then, the inclination angle of the central axis B3 with respect to the central axis B3 (reference central axis) when the virtual orthogonal plane and the central axis B3 are orthogonal to each other is the inferior angle θ1.

  In the present embodiment, the axial direction D1 (thickness direction D3) and the main radiation direction D2 of the object to be processed 100 extend along the horizontal direction. Therefore, in this embodiment, the inferior angle θ1 is an angle formed by the axial direction D1 (thickness direction D3) and the main radiation direction D2 on the virtual horizontal plane.

  With reference to FIGS. 1 to 6, by setting the inferior angle θ1 to be 45 ° or less, it is possible to more reliably suppress the uneven transfer of heat in the outer peripheral portion of the object to be processed 100. That is, by setting the inferior angle θ1 to 1/2 or less of 90 ° which is a right angle, the heat from the heaters 14 and 15 is evenly transferred to the entire surface of the object 100 to be processed. This makes it possible to further reduce the deviation in the timing of starting transformation (hereinafter, also simply referred to as transformation timing) in each part of the workpiece 100 when the workpiece 100 is being heat-treated. As a result, it is possible to further reduce the occurrence of transformation stress (that is, the stress caused by the shift of transformation timing) in the object to be processed 100. As a result, the strain (for example, thermal strain) of the object to be processed 100 caused by the internal stress of the object to be processed 100 can be further reduced. In particular, it is possible to further reduce the elliptic distortion in which the ring-shaped object to be processed 100 having a substantially perfect circle is distorted into an elliptical shape.

  If the inferior angle θ1 exceeds 45 °, the degree to which the distribution of heat transmitted to the object to be processed 100 along the main radiation direction D2 becomes non-uniform within the object to be processed 100 increases. As a result, when the object to be processed 100 is being heat-treated, the shift in transformation timing in the object to be processed 100 becomes large. As a result, the transformation stress in the object to be processed 100 increases. Therefore, the strain of the object to be processed 100 due to the internal stress of the object to be processed 100 becomes larger.

  The inferior angle θ1 is more preferably 30 ° or less. When the inferior angle θ1 is 30 ° or less, which is ⅔ of 45 °, the degree of heat received by the inner peripheral surface 100a and the outer peripheral surface 100b of the ring-shaped object to be processed 100 can be made more uniform. As a result, the strain of the object to be processed 100 due to the internal stress of the object to be processed 100 becomes smaller. The inferior angle θ1 is more preferably 15 ° or less, which is ½ of 30 °. The most preferable value of the inferior angle θ1 is zero.

  The inferior angle θ1 is adjusted, for example, by changing the direction of the holder 2 with respect to the tube 16 of each of the heaters 14 and 15 in a plan view. In addition, the inferior angle θ1 can be adjusted by changing the direction in which the support member 27 extends with respect to the bottom frame portion 21 of the holder 2 in plan view.

  In this way, the holder 2 makes the object to be processed 100 and the heater unit 6 face each other, and the inferior angle θ1 between the axial direction D1 (thickness direction D3) of the object to be processed 100 and the main radiation direction D2 is 45. The object 100 to be processed is arranged so that the temperature becomes equal to or less than (including zero). At this time, the heater unit 6 is arranged outside the object 100 to be processed. That is, the heater unit 6 is arranged outside the inner peripheral surface 100a of the object 100 to be processed and the area surrounded by two virtual planes that respectively pass through both ends of the object 100 to be processed in the axial direction D1. Further, the object to be processed 100 is arranged between the tube 16 of the first heater 14 and the tube 16 of the second heater 15 as a plurality of heating units provided in the heater unit 6.

  As shown in FIG. 5, when viewed in the first alignment direction E1, the first support portion 31 and the second support portion 32 are in point contact with the outer peripheral surface 100a of the object 100 to be processed. The bottom 100e of the object 100 to be processed is arranged between the first support 31 and the second support 32. In the present embodiment, the height positions of the first support portion 31 and the second support portion 32 are aligned, and they are symmetrically located in the second alignment direction E2.

  The first support portion 31 and the second support portion 32 have a predetermined angular interval θ2. In other words, when the first support part 31 and the second support part 32 when the object to be processed 100 is placed are viewed in the axial direction D1 of the object to be processed 100, the first support part 31 and the second support part 32. 32 has a predetermined angular interval θ2.

  More specifically, the first line when the first support portion 31 and the second support portion 32 when the workpiece 100 is placed on the support member 27 is viewed in the axial direction D1 of the workpiece 100. The inferior angle formed by the segment B1 and the second line segment B2 is defined as the angular interval θ2. The first line segment B1 is a line segment that connects the central axis B3 of the object to be processed 100 and the first support portion 31. The second line segment B2 is a line segment that connects the central axis B3 of the object 100 to be processed and the second support portion 32. It can be said that the angular interval θ2 is the interval between the first support portion 31 and the second support portion 32 around the central axis B3 of the object 100 to be processed.

  The angular interval θ2 is preferably set in the range of 20 ° to 60 °. By setting the angular interval θ2 to 20 ° or more, the compressive stress acting on each part of the object to be processed 100 supported by these supporting parts 31 and 32 can be made more uniform. Therefore, the strain of the object to be processed 100 can be further reduced. Further, by setting the angular interval to 60 ° or less, when the object 100 to be processed is thermally expanded by the heat treatment, the object 100 is sandwiched between the two support portions 31 and 32 due to expansion. Can be suppressed. As a result, it is possible to prevent the workpiece 100 from being deformed so as to bite into the two support portions 31 and 32.

  Note that, of the facing surface 28 of each support member 27, the portion forming the first support portion 31 and the second support portion 32 may have a projection shape. In this case, the first support portion 31 and the second support portion 32 support the object to be processed 100 in a point contact state.

  A plurality of workpieces 100 are arranged on the pair of support members 27, 27 at substantially equal intervals along the first arrangement direction E1 (main radiation direction D2 in the present embodiment). Further, a plurality of pairs of the first support portion 31 and the second support portion 32 are arranged along the second arrangement direction E2 orthogonal to the first arrangement direction E1 in plan view. Thereby, the objects 100 to be processed can be arranged in a plurality of rows in the traveling direction X1. In the present embodiment, the workpieces 100 in each row adjacent to the traveling direction X1 are completely separated from each other in the traveling direction X1, and are arranged so that their positions in the traveling direction X1 do not overlap.

  In this embodiment, a lower holder 2aa, a middle holder 2b, and an upper holder 2c are provided as a plurality (three in the present embodiment) of holders 2.

  In this embodiment, the lower holder 2a, the middle holder 2b, and the upper holder 2c are stacked in this order. The bottom frame portion 21 of the lower holder 2 a is supported by the pedestal 7 of the lower holder 2 a. The middle holder 2b is placed on the four vertical frame portions 22 to 25 of the lower holder 2a. The upper holder 2c is placed on the four vertical frame portions 22 to 25 of the middle holder 2b. As described above, by stacking the plurality of holders 2, a large number of objects 100 to be processed can be heat-treated collectively.

  An air flow stirred by a stirring device 8 for stirring the gas in the heat treatment furnace 5 is applied to the object to be processed 100 arranged in the heat treatment furnace 5.

  With reference to FIG. 1 and FIG. 2, stirring device 8 is provided to make temperature and gas components in heat treatment furnace 5 more uniform. The stirring device 8 has a stirring fan 33 that is rotationally driven by an electric motor or the like. The agitation fan 33 is, for example, a centrifugal fan, and is configured to generate a wind outward in the radial direction of the agitation fan 33. The stirring fan 33 is arranged above the heat treatment furnace 5. In the present embodiment, the stirring fan 33 is arranged directly above the base 7 and the holder 2. The operation of the stirring device 8 is controlled by the control unit 4. Further, the atmospheric gas for heat treatment is supplied from the atmospheric gas supply unit 9 into the heat treatment furnace 5.

  The atmospheric gas supply unit 9 is configured to supply an atmospheric gas, which is a heat treatment gas for performing a desired heat treatment to the object 100, to the heat treatment furnace 5. The atmospheric gas supply unit 9 has a pipe connected to the heat treatment furnace 5, and the pipe is connected to the pump 9a and a tank (not shown). The operation of the pump 9a of the ambient gas supply unit 9 is controlled by the control unit 4. As a result, the atmospheric gas stored in the tank is supplied into the heat treatment furnace 5 by the atmospheric gas supply unit 9.

  In the present embodiment, a gas containing carbon such as carbon monoxide (CO) gas is used as the heat treatment gas. The carbon potential (mass%) in this gas is set to be larger than the carbon content of the carbon steel that is the base material of the object 100 to be processed. Then, in the present embodiment, the object to be processed 100 is exposed to the atmospheric gas set to the carbon potential Cp in the range of 0.6% to 1.0% during heating in the heat treatment apparatus 1.

  More specifically, the carbon potential Cp of the atmospheric gas in the heat treatment furnace 5 is set based on 0.77%, which is the carbon potential at the eutectoid point in the equilibrium diagram of the Fe—C alloy. By setting the carbon potential Cp in the range of 0.6% to 1.0%, the carbon content on the surface of the object to be processed 100 becomes close to 0.77% during the heat treatment of the object to be processed 100. .. This makes it possible to further shorten the time during which the object to be processed 100 is in the state of ferrite + austenite during the heat treatment of the object to be processed 100. Thereby, the transformation stress generated in the object 100 to be processed can be further reduced. In the present embodiment, the carbon potential Cp in the atmospheric gas is set to be three times or more the carbon potential of the base material of the object 100 to be treated, which is 0.2%.

  In the present embodiment, more preferably, the carbon potential Cp of the atmospheric gas is 0.77% ± 0.1%, that is, 0.67% to 0.87%. By setting the carbon potential Cp of the atmospheric gas to 0.77% ± 0.1%, the carbon potential Cp of the atmospheric gas can be substantially set to the carbon potential at the eutectoid point. As a result, during heat treatment of the object to be processed 100, the carbon content on the surface of the object to be processed 100 becomes close to 0.77%, and the time when the object to be processed 100 is ferrite + austenite can be further shortened. .. Thereby, the transformation stress in the object 100 to be processed can be further reduced.

  The heat treatment operation of the object 100 in the heat treatment furnace 5 is controlled by the control unit 4. The control unit 4 has a configuration of outputting a predetermined output signal based on a predetermined input signal, and can be formed using, for example, a safety programmable controller or the like. The safety programmable controller refers to a publicly certified programmable controller having a safety function of SIL2 or SIL3 of JIS (Japanese Industrial Standard) C 0508-1. The control unit 4 may be formed using a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory).

  The control unit 4 is configured to calculate the carbon potential Cp of the atmospheric gas in the heat treatment furnace 5 based on the oxygen concentration detection result from the oxygen sensor 13. Further, the control unit 4 controls the pump 9a (not shown) of the atmospheric gas supply unit 9 based on the detected carbon potential Cp and the like to control the flow rate of the atmospheric gas supplied to the heat treatment furnace 5 and the like. Is configured. As a result, the control unit 4 controls the carbon potential Cp of the atmosphere gas in the heat treatment furnace 5. Further, the control unit 4 is configured to be able to control the flow rate of the combustion gas supplied to each of the heaters 14 and 15. Thereby, the control unit 4 can control the temperature in the heat treatment furnace 5 based on the temperature detection result detected by the temperature sensor 12.

  Next, an example of the heat treatment operation in the heat treatment apparatus 1 will be described. FIG. 7 is a flow chart for explaining an example of the heat treatment operation in the heat treatment apparatus 1. FIG. 8 is a graph showing an example of temperature control of the object 100 to be processed in the heat treatment apparatus 1. FIG. 9 is a schematic equilibrium state diagram of the Fe—C alloy for explaining the state of the object 100 to be heat-treated in the heat treatment apparatus 1. In the following, when the description is made with reference to the flowchart, the description will be given with reference to the drawings other than the flowchart as appropriate.

  In the heat treatment operation of the heat treatment apparatus 1, first, an operation of arranging the object 100 to be processed is performed by, for example, an operator or an automatic arrangement device (not shown) by a machine (step S1). Specifically, for example, a worker places the object 100 to be processed in each of the holders 2a, 2b, 2c. Then, the worker mounts the lower holder 2a on the pedestal 7. Further, the middle holder 2b is placed on the lower holder 2a. Further, the upper holder 2c is placed on the middle holder 2b. The holders 2a, 2b, 2c may be moved by a transfer device (not shown).

  As a result, the holder 2 is arranged in the heat treatment furnace 5 in the above-described mode described with reference to FIGS. 1 to 4. That is, the tubes 16 of the first heaters 14 and the tubes 16 of the second heaters 15 of the heater units 6 arranged on the outer side of each of the objects to be processed 100 in a state where the objects to be processed 100 and the heater unit 6 face each other. So that the holder 2 is positioned between them, and further, the subordination angle θ1 formed by the axial direction D1 of each object to be processed 100 and the main radiation direction D2 of the heater unit 6 is 45 ° or less (including zero). The object to be processed 100 is placed in the heat treatment furnace 5.

  Next, the workpiece 100 in the heat treatment furnace 5 is heated by using the heater unit 6 (step S2). Specifically, the control unit 4 controls the heating operation of the heater unit 6 and also controls the supply amount of the atmospheric gas supplied from the atmospheric gas supply unit 9, so that the atmospheric temperature and the carbon in the heat treatment furnace 5 are controlled. Control the potential Cp. Thereby, the control unit 4 controls the heat treatment operation of the object 100 to be processed. More specifically, the control unit 4 controls the heating operation of the heater unit 6 so that the relationship between time and the temperature of the object to be processed 100 shown in FIG. 8 is realized.

  In the following, unless otherwise specified, the term “temperature” refers to the temperature of the atmospheric gas in the heat treatment furnace 5. In step S2, the control unit 4 first heats the atmospheric gas in the heat treatment furnace 5 to the A1 transformation point. The A1 transformation point may be in the range of 727 ° C to 810 ° C, for example. The A1 transformation point may be in the range of 750 ° C to 850 ° C.

  After the temperature rises to the A1 transformation point, this temperature is maintained for a predetermined time until a predetermined timing T1. As a result, the entire object 100 including the inside thereof is heated to the A1 transformation point. Next, the control unit 4 raises the temperature in the heat treatment furnace 5 from the A1 transformation point to the A3 transformation point by performing control to increase the electric power supplied to the heater unit 6 (timings T1 to T2, for example). ).

  Between the A1 transformation point and the A3 transformation point, the atmospheric gas and the object 100 to be processed are heated at a temperature rising rate (temperature rising rate) within the range of 0.5 ° C./min to 10 ° C./min. When the temperature increase rate of the object to be processed 100 is equal to or higher than the above lower limit value, the time required to transform the object to be processed 100 from the A1 transformation point to the A3 transformation point can be further shortened. Further, since the temperature increase rate of the object to be processed 100 is equal to or lower than the above upper limit value, when the object to be processed 100 is transformed from the A1 transformation point to the A3 transformation point, the object to be treated is treated from the outer surface of the object 100 to be treated. When heat is transferred to the inside of the object 100, the temperature difference between the outer surface and the inside of the object 100 to be processed can be made sufficiently small. Thereby, the transformation stress inside the object to be processed 100 can be further reduced. Therefore, the strain of the object to be processed 100 can be further reduced. In other words, when each part of the object to be processed undergoes austenite transformation, the unevenness of transformation timing (that is, nonuniformity of transformation timing) can be further reduced.

  It is more preferable that the atmosphere gas and the object to be treated 100 are heated at a temperature rising rate within the range of 0.5 ° C./min to 1.0 ° C./min between the A1 transformation point and the A3 transformation point. .. Accordingly, when heat is transferred from the outer surface of the object to be processed 100 to the inside of the object to be processed 100, the temperature difference between the outer surface of the object to be processed 100 and the inside can be significantly reduced.

  Further, the object 100 to be processed is heated to the A3 transformation point or higher in the atmosphere gas of the carbon potential Cp described above. At this time, the carbon potential inside the object to be processed 100 does not substantially change. On the other hand, the carbon potential of the outer surface of the object to be treated 100 increases due to the heat treatment.

  More specifically, the inside of the object 100 to be processed is heated to a temperature higher than the A3 transformation point by following the course defined by the line L1 in FIG. At this time, the inside of the object to be processed 100 is in a state of ferrite + cementite at a temperature below the A1 transformation point. Then, the inside of the object to be processed 100 is transformed into a state of ferrite + austenite when exceeding the A1 transformation point, as indicated by the line L1. When the temperature inside the object to be processed 100 further rises and the internal temperature of the object to be processed 100 exceeds the A3 transformation point, ferrite disappears and the material is transformed into an austenite state. The carbon potential inside the object 100 does not change even when heated to a temperature exceeding the A3 transformation point.

  Here, in the heat treatment, the temperature of the outer surface of the object to be treated 100 first rises, and then the temperature of the inner portion thereof rises. Therefore, in the present embodiment, the state of the atmospheric gas in the heat treatment furnace 5 is controlled so as to be in the state near the eutectoid point (for example, 727 ° C., carbon potential Cp = 0.77%). Thereby, the effect of reducing the distortion of the object to be processed 100 can be further enhanced.

  In the present embodiment, the carbon potential of the outer surface of the object to be processed 100 increases by following the course indicated by the line L2 (for example, L21, L22, L23) in FIG. It converges on the carbon potential Cp of the atmospheric gas. The line L21 indicates the case where the carbon potential Cp of the atmospheric gas is at the lower limit (Cp = 0.6%) of the above range. The line L22 indicates the case where the carbon potential Cp of the atmospheric gas is equal to the carbon potential at the eutectoid point (Cp = 0.77%). The line L23 shows the case where the carbon potential Cp in the atmospheric gas is at the upper limit (Cp = 1.0%) of the above range.

  The outer surface of the object to be processed 100 reacts with carbon in the atmosphere gas as the temperature of the atmosphere gas in the heat treatment furnace 5 rises. As a result, the carbon potential on the outer surface of the object to be processed 100 increases. In particular, on the outer surface of the object 100 to be treated, the carbon potential increases in a manner substantially proportional to the temperature increase until reaching the A1 transformation point. Then, when the temperature of the outer surface of the object to be processed 100 becomes close to the A1 transformation point, the carbon potential of the outer surface of the object to be processed 100 becomes substantially constant while slightly increasing as the temperature of the outer surface of the object to be processed 100 increases. Become. The temperature of the outer surface of the object to be processed 100 is lower than that of the inside of the object to be processed 100 until it is transformed into an austenite state.

  For example, when the carbon potential Cp of the atmospheric gas in the heat treatment furnace 5 is set to the above lower limit, as shown by the line L21, when the outer surface of the object 100 to be processed reaches the A1 transformation point, ferrite + cementite. The state transforms to ferrite + austenite state. The temperature difference Δt21 from when the outer surface of the object 100 reaches the A3 transformation point to the A1 transformation point is calculated from the temperature difference Δt1 when the inside of the object 100 reaches the A3 transformation point from the A1 transformation point. Is also small. Therefore, on the outer surface of the object 100 to be processed, the transformation stress can be further reduced from the A1 transformation point to the A3 transformation point. As a result, the strain on the outer surface of the object to be processed 100 can be further reduced.

  On the other hand, for example, when the carbon potential Cp of the atmospheric gas in the heat treatment furnace 5 is set to 0.77% which is the carbon potential at the eutectoid point, the outer surface of the object 100 to be treated is When the A1 transformation point is reached, the ferrite + cementite state is transformed into the austenite state substantially immediately. In this case, the temperature difference from the outer surface of the object to be processed 100 reaching the A1 transformation point to the A3 transformation point is substantially zero. Therefore, on the outer surface of the object 100 to be processed, the transformation stress can be further reduced from the A1 transformation point to the A3 transformation point. As a result, the strain on the outer surface of the object to be processed 100 can be further reduced.

  Further, for example, when the carbon potential Cp of the atmospheric gas in the heat treatment furnace 5 is set to the above upper limit, as shown by the line L23, when the outer surface of the object to be processed 100 reaches the A1 transformation point, ferrite Transform from + cementite state to austenite + cementite state. The temperature difference Δt23 from when the outer surface of the object to be processed 100 reaches the Acm transformation point to the A1 transformation point is smaller than the temperature difference Δt1 from when the inside of the object to be treated 100 reaches the A3 transformation point from the A1 transformation point. Is also small. Therefore, on the outer surface of the object 100 to be processed, the transformation stress can be further reduced from the A1 transformation point to the Acm transformation point. As a result, the strain on the outer surface of the object to be processed 100 can be further reduced. As described above, the distortion of the outer surface of the object to be processed 100 can be further reduced regardless of the course of the lines L21, L22, and L23.

  As described above, in the heating step (step S2), the entire object 100 to be processed is heated beyond the A1 transformation point to the A3 transformation point. The control unit 4 performs control to maintain the temperature of the atmospheric gas in the heat treatment furnace 5 at the same temperature as the A3 transformation point for a predetermined period (timing T2 to T3). As a result, the entire temperature of the object to be processed 100 becomes the A3 transformation point. After that, the control unit 4 causes the heater unit 6 to perform the heating operation so as to further raise the atmospheric gas temperature in the heat treatment furnace 5 to the maximum temperature tmax during the heat treatment (timing T3 to T4).

  It should be noted that the maximum temperature tmax is a temperature set for causing the object 100 to be carburized in the present embodiment. This maximum temperature tmax is set to a temperature required for a target heat treatment such as diffusion treatment when subjecting the object to be processed 100 to another heat treatment such as diffusion treatment. The maximum temperature tmax is set to, for example, about 800 ° C to 960 ° C. In addition, the control unit 4 sets the temperature increase rate when heating the inside of the object to be processed 100 from the A3 transformation point to the maximum temperature tmax to the heating rate when heating the inside of the object to be treated 100 from the A1 transformation point to the A3 transformation point. Set higher than the temperature rising rate.

  The control unit 4 performs the heat treatment on the object to be processed 100 by maintaining the temperature of the atmospheric gas in the heat treatment furnace 5 at the maximum temperature tmax for a predetermined period. After that, the control unit 4 lowers the temperature of the object to be processed 100, for example, by stopping the heating operation by the heater unit 6 (step S3). After that, the object 100 to be processed is carried out from the heat treatment furnace 5, and then subjected to other processing such as quenching. As described above, the tube 16 of the heater unit 6 is arranged perpendicular to the ceiling wall 5a of the heat treatment furnace 5 from the viewpoint of durability and the like.

  Conventionally, from the viewpoint of heat treatment distortion, in consideration of the temperature distribution in one object to be processed, it is not necessary to arrange the object to be processed in an upright posture and to support the object to be treated from below, The object was in a lying position. Further, conventionally, the object to be processed is heat-treated by suspending the object to be processed in a heat treatment furnace by using a bar configured to receive the inner peripheral surface of the object to be processed in a ring shape. There was also.

  On the other hand, in the present embodiment, in each of the circular object 100 to be processed, in order to suppress the temperature difference in the circumferential direction of the object 100 to be processed, the axial direction D1 and the main radiation direction D2 are suppressed. The inferior angle θ1 is set to 45 ° or less. Similarly, an inferior angle θ1 formed by the thickness direction D3 and the main radiation direction D2 is set to 45 ° or less. In addition, in the present embodiment, the outer peripheral surface 100a of the object to be processed 100 is configured to support a downward position, and the angular interval θ2 between the first support portion 31 and the second support portion 32 is 20. It is set within the range of ° to 60 °. Accordingly, the holder 2 can support the object to be processed 100 in a posture in which tensile stress is unlikely to occur in the object to be processed 100. Thereby, the distortion generated in the object 100 to be processed can be significantly reduced.

  Further, in this embodiment, the supply of the atmospheric gas is controlled with reference to the carbon potential at the eutectoid point in the equilibrium diagram of the Fe—C alloy. Thereby, the strain of the object to be processed 100 during the austenite transformation becomes smaller. Further, by setting the temperature rising rate of the object to be processed 100 to the value described above, the temperature difference in the object to be processed 100 when the object to be processed 100 undergoes austenite transformation can be made smaller. As a result, the strain of the object to be processed 100 becomes smaller. As a result, it is possible to heat-treat a large number of objects 100 to be processed by the heat treatment apparatus 1 in a short time while suppressing the distortion of the objects 100 to be processed.

  As described above, according to the present embodiment, the inferior angle θ1 formed by the axial direction D1 (thickness direction D3) of each workpiece 100 and the main radiation direction D2 of the heater unit 6 is 45 ° or less (including zero). The object 100 to be processed is arranged so that With this configuration, the heat from the heater unit 6 is evenly transferred to each part of the object 100 to be processed. This makes it possible to further reduce the temperature difference in the object to be processed 100 when the object to be processed 100 is heated by the heater unit 6. More specifically, the temperature difference of the object 100 to be processed in the circumferential direction of the object 100 can be further reduced. In particular, when the axial direction D1 and the main radiation direction D2 coincide with each other, that is, when the inferior angle θ1 is zero, the temperature difference in the object 100 to be processed in the circumferential direction of the object 100 can be significantly reduced. Further, since the object 100 to be processed is arranged between the tubes 16 of the first heater 14 and the second heater 15, the object 100 to be processed is heated more uniformly in the main radiation direction D2 where the plurality of tubes 16 face each other. As a result, the temperature difference in the object to be processed 100 can be further reduced. As a result, it is possible to suppress the occurrence of stress imbalance in the object to be processed 100. In particular, in one object 100 to be processed, the timings at which the respective parts undergo austenite transformation can be made more uniform. Further, as a result of suppressing the occurrence of stress imbalance in the object 100 to be processed, the object 100 to be processed can be heat-treated in a shorter time. This makes it possible to further reduce the distortion caused by the heat treatment in the metal-made workpiece 100 formed in a circular shape, and further shorten the heat treatment time of the workpiece 100. More specifically, the elliptic distortion in which the object to be processed 100 is distorted in an elliptical shape can be further reduced. Further, when the object to be processed 100 is heated to the A1 transformation point or higher, the timing at which the temperature of each part in the object to be treated 100 passes the A1 transformation point can be made more uniform. As a result, it is possible to suppress the occurrence of transformation stress in the object to be processed 100.

  Further, according to the present embodiment, when the processing object 100 is arranged in the heat treatment furnace 5 (step S1), the plurality of processing objects 100 are arranged along the main radiation direction D2. According to this configuration, the plurality of objects to be processed 100 can be collectively heat-treated while reducing the strain.

  Further, according to the present embodiment, each processing target object 100 is arranged in an upright posture, and the axial direction D1 of each processing target object 100 is along the horizontal direction. With this configuration, it is possible to suppress the tensile stress from being generated in the object to be processed 100. Thereby, the strain caused by the stress of the object to be processed 100 can be significantly reduced.

  Further, according to the present embodiment, when the object 100 to be processed is placed in the heat treatment furnace 5 (step S1), the holder 2 supports the outer peripheral surface of the object 100 to be processed from below. With this configuration, it is possible to suppress the tensile stress from being generated in the object to be processed 100. Thereby, the strain caused by the stress of the object to be processed 100 can be significantly reduced.

  In addition, according to the present embodiment, the support portions 31 and 32 of the holder 2 support the object 100 to be processed in line contact or point contact. According to this configuration, the holder 2 can support the object to be processed 100 in a state in which the expansion and contraction of the object to be processed 100 during the heat treatment of the object to be processed 100 are suppressed. As a result, the strain of the object 100 to be processed due to the heat treatment can be further reduced.

  Further, according to the present embodiment, the angular interval θ2 between the first support portion 31 and the second support portion 32 around the central axis B3 of the object to be processed 100 is set in the range of 20 ° to 60 °. According to this configuration, by setting the angular interval θ2 between the first support portion 31 and the second support portion 32 to be 20 ° or more, it acts on each portion of the object to be processed 100 supported by these support portions 31 and 32. The stress applied can be made more uniform. Therefore, the strain of the object to be processed 100 can be further reduced. Further, by setting the angular interval θ2 between the first support portion 31 and the second support portion 32 to be 60 ° or less, when the workpiece 100 thermally expands due to the heat treatment, the two support portions 31, 32 are expanded by the expansion. It can suppress that the to-be-processed object 100 is pinched between them. As a result, it is possible to prevent the workpiece 100 from being deformed so as to bite into the two support portions 31 and 32.

  Further, according to the present embodiment, when each object 100 to be processed is heated (step S2), the object 100 to be processed is an atmospheric gas set to a carbon potential in the range of 0.6% to 1.0%. Heated in. According to this configuration, when heating the object to be processed 100, the time required for each part of the surface of the object to be processed 100 to shift from the area of ferrite + cementite to the area of austenite can be further shortened. As a result, the object to be treated 100 can be transformed into austenite more uniformly.

  Further, according to the present embodiment, when heating the object 100 to be processed (step S2), the heater unit 6 heats the object 100 to be processed at least between the A1 transformation point and the A3 transformation point. According to this configuration, each part of the object to be processed 100 can undergo austenite transformation more uniformly.

  Further, according to the present embodiment, when each of the objects to be processed 100 is heated (step S2), the objects to be processed 100 undergo A1 transformation at a temperature increase rate of 0.5 ° C./min to 10 ° C./min. It is heated from the point to the A3 transformation point. According to this configuration, since the temperature rising rate of the object to be processed 100 is equal to or higher than the above lower limit value, the time required to transform the object to be processed 100 from the A1 transformation point to the A3 transformation point can be further shortened. Further, since the temperature increase rate of the object to be processed 100 is equal to or lower than the above upper limit value, when the object to be processed 100 is transformed from the A1 transformation point to the A3 transformation point, the object to be treated is treated from the outer surface of the object 100 to be treated. When heat is transferred to the inside of the object 100, the temperature difference between the outer surface and the inside of the object 100 to be processed can be made sufficiently small. Thereby, the transformation stress inside the object to be processed 100 can be further reduced. Therefore, the strain of the object to be processed 100 can be further reduced. In other words, when each part of the object to be processed 100 undergoes austenite transformation, unevenness in transformation timing (that is, nonuniformity of transformation timing) can be further reduced.

  Moreover, according to this embodiment, the to-be-processed object 100 is formed in a ring shape. With this configuration, in the ring-shaped object to be processed 100, the degree of temperature change in each part can be made more uniform. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  Further, according to the present embodiment, the object 100 to be processed has an inner peripheral portion formed in a shape similar to the shape of the outer peripheral portion of the object 100 to be processed. With this configuration, the degree of temperature change of each part can be made more uniform in each of the objects to be processed 100 formed in the annular shape and having the substantially uniform thickness TH1. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  Further, when the object 100 to be processed is a bearing race or gear, a bearing or gear with high dimensional accuracy can be manufactured.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In the following, points different from the above-described embodiment will be mainly described, and configurations similar to those in the above-described embodiment may be denoted by the same reference numerals in the drawings and description thereof may be omitted.

  FIG. 10 is a schematic plan view of the holder 2A and the heater unit 6 included in the heat treatment apparatus 1 according to the second embodiment of the present invention. FIG. 11 is a schematic side view of a main part showing the holder 2A and the object to be processed 100 held by the holder 2A. FIG. 12 is a schematic front view of the main part showing the holder 2A and the object to be processed 100 held by the holder 2A. FIG. 13 is a schematic plan view of the main part showing the holder 2A provided in the heat treatment apparatus 1 according to the second embodiment of the present invention and the object 100 to be processed held by the holder 2A. Note that, in FIGS. 11 and 13, the processed objects 100 in the second processed object row 42, which will be described later, are cross-hatched in order to make the processed objects 100 easy to see.

  With reference to FIGS. 10 to 13, the holder 2A of the present embodiment is suitable for holding a plurality of circular objects 100 to be heat-treated, and particularly, a portion including at least a part of a ring shape. It is suitable for holding the ring-shaped object 100 to be processed which is constituted by the annular portion. The holder 2A has a configuration for suppressing a difference between the supply mode of the atmospheric gas to the inner peripheral portion and the supply mode of the atmospheric gas to the outer peripheral portion for each of the workpieces 100. Further, the holder 2A of the present embodiment has a configuration for increasing the number of objects to be processed 100 that can be held at one time as much as possible. The object 100 to be processed is arranged with the holder 2A in a manner described later (step S1), and then subjected to a heating process (step S2) and a cooling process (step S3). Hereinafter, the holder 2A will be described more specifically.

  The receiving portion 26A of the holder 2A extends along the first arrangement direction E1 and is configured to receive the plurality of objects 100 to be processed. As described above, the first arrangement direction E1 is along the axial direction D1 (thickness direction D3) of the object 100 to be processed held by the receiving portion 26A. Further, the receiving portion 26A arranges a plurality of objects 100 to be processed in a state where the openings 100c of the objects 100 to be processed are standing upright and the openings 100c face the first arrangement direction E1 side. Is configured. Further, the receiving member 26A is configured to dispose the two objects to be processed 100 adjacent to each other in the first arrangement direction E1 while being offset from each other in the second arrangement direction E2 orthogonal to the first arrangement direction E1.

  More specifically, each support member 27A of the receiving portion 26A extends along the first alignment direction E1 and supports the lower part of the outer peripheral surface of the object 100 to be processed, including the downward surface. It is arranged. Also in the present embodiment, the first support portion 31A and the second support portion 32A of the support member 27A are formed in a linear shape, and the object to be processed 100 and the support member 27A are in line contact with each other. The object 100 to be treated and the support member 27A preferably have a small contact area, and may be point contact, line contact, or surface contact.

  Both ends of each support member 27A are received by the upper portion of the bottom frame portion 21A of the holder 2A. Further, a reinforcing beam 35 extending along the second arrangement direction E2 and fixed to the bottom frame portion 21A is provided. The reinforcing beams 35 are arranged at, for example, two positions in the first arrangement direction E1. Both ends of each reinforcing beam 35 are fixed to the bottom frame portion 21A. Then, each support member 27A is arranged on these reinforcing beams 35.

  The support members 27A are arranged at equal pitches at a predetermined pitch P1 in the second arrangement direction E2. The facing surface 28 of each support member 27A extends straight along the first alignment direction E1. Then, the pair of support members 27A, 27A adjacent to the second arrangement direction E2 are configured to support one workpiece 100.

  In the present embodiment, among the plurality of support members 27A, the support members 27A arranged at both ends in the second alignment direction E2 support the workpieces 100 in one workpiece row 41. On the other hand, among the plurality of support members 27A, the support members 27A arranged at other than the both ends in the second arrangement direction E2 support the objects 100 to be processed of the two object rows 41 and 42. In addition, the to-be-processed object line 41 contains the several to-be-processed object 100 arranged in the 1st arrangement | positioning direction E1 in the state which the position of the 2nd arrangement | positioning direction E2 was aligned. Similarly, the processing object row 42 includes a plurality of processing objects 100 arranged in the first arrangement direction E1 in a state where the positions in the second arrangement direction E2 are aligned.

  In the present embodiment, a processed object row 41 as a large number of processed object rows and a processed object row 42 as a large number of processed object rows are formed. The processing object rows 41 and 42 each include a plurality of processing objects 100 arranged along the first arrangement direction E1. The object rows 41 and the object rows 42 are alternately formed along the second arrangement direction E2. Then, the object rows 41 and 42 other than the object rows 41 at both ends in the second arrangement direction E2 are one support member together with the object row 41 or the object row 42 adjacent to the second arrangement direction E2. 27A is shared. Therefore, of the plurality of support members 27A, the facing surfaces 28 of the support members 27A that are arranged at other than both ends in the second alignment direction E2 are in contact with the two objects 100 to be processed at two locations. The facing surface 28 is in contact with the object 100 to be processed of one object row 41 or the object row 42 at the first support portion 31A, and is in contact with another object row 41 or object line 42. The object 100 to be processed is in contact with the second supporting portion 32A. Note that each support member 27A may be configured to support the object 100 to be processed in only one object row 41 or one object row 42.

  In the present embodiment, a first processed object row 41 and a second processed object row 42 are formed as the processed object rows adjacent to each other in the second arrangement direction E2. The objects 100 to be processed in the second object row 42 and the objects 100 to be processed in the first object row 41, which are adjacent to each other in the second arrangement direction E2, are displaced in the second arrangement direction E2. In the state, they are arranged along the first arrangement direction E1. In the present embodiment, one object 100 to be processed in the first object row 41 and one object 100 to be processed in the second object row 42 alternate when going along the first arrangement direction E1. Lined up. With such a configuration, one processing target 100 in the first processing target row 41 and one processing target 100 in the second processing target row 42 are arranged in a zigzag pattern.

  Further, the two objects to be processed 100 adjacent to each other in the first arrangement direction E1 are arranged such that the end surfaces 100d facing each other are in contact with each other. That is, the one end surface 100d of the processing object 100 of the first processing object row 41 is in contact with the corresponding one end surface 100d of the corresponding processing object 100 of the second processing object row 42. Therefore, the pair of end faces 100d and 100d of the object 100 to be processed, which are arranged in the middle portion of the first object direction row 41 in the first alignment direction E1, are two object surfaces of the second object row 42. It is sandwiched between the corresponding one end faces 100d of the object 100. Similarly, the pair of end surfaces 100d and 100d of the object 100 to be processed, which are arranged in the middle portion of the second processing object row 42 in the first alignment direction E1, are the two objects to be processed of the first object row 41. It is sandwiched between the corresponding one end faces 100d of the processed objects 100.

  In the present embodiment, the first processed object rows 41 and the second processed object rows 42 are arranged alternately in the second arrangement direction E2. That is, the first processed object row 41, the second processed object row 42, the first processed object row 41, the second processed object row 42, ... Are arranged in this order along the second arrangement direction E2. There is. As described above, in the present embodiment, a large number of object rows are formed by the two kinds of object rows 41 and 42.

  With the above configuration, in the second arrangement direction E2, one object row is opened and the same object row (first object row 41 or second object row 42) is arranged. ..

  As shown in FIG. 12, when the processing object row 41 or the processing object row 42 is viewed from the first arrangement direction E1, each processing object 100 in the processing object row is an adjacent processing object. An area having a length equal to or smaller than half the outer diameter DR1 of the object to be processed 100 is arranged to overlap the object to be processed 100 in the row 42 or the object row 41 in the second alignment direction E2. For example, three processing object rows 41a, 42a, 41b arranged in the second arrangement direction E2 will be described. Of these three object rows 41a, 42a, 41b, the object 100 in the middle object row 42a extends vertically through the central axis B3 of the object 100 in one object row 41a. The first virtual plane PL1 and the second virtual plane PL2 that extends vertically through the central axis B3 of the workpiece 100 of the other workpiece row 41b are arranged in a space sandwiched between the first virtual plane PL1 and the second virtual plane PL2.

  By arranging the objects 100 to be processed on the holder 2A in the above-described manner, a large number of objects 100 to be processed can be placed on the holder 2A. For example, the holder 2A has the same length, width and height as the holder 2 in the first embodiment. On the other hand, the number of objects to be processed 100 that can be placed on the holder 2A at a time can be approximately 125% of the number of objects to be processed 100 that can be placed on the holder 2 at a time.

  With reference to FIGS. 10 to 13, the vertical frame portions 22A and 23A as the front frame portion and the rear frame portion of the holder 2A respectively include a plurality of columns arranged at a predetermined pitch in the second alignment direction E2, It has a beam portion connecting the upper ends of these columns. The vertical frame portions 24A and 25A as a pair of horizontal frame portions of the holder 2A respectively include a plurality of pillars arranged at a predetermined pitch in the first arrangement direction E1 and a beam portion connecting the upper ends of these pillars. And have. The vertical frame portions 22A to 25A are formed in a mesh with such a configuration.

  Further, L-shaped stoppers 43 are provided at the four corners of the upper portion of the holder 2A, respectively. Each stopper 43 projects upward from the upper ends of the four vertical frame portions 22A, 23A, 24A, 25A of the holder 2A. When another holder 2A is stacked above the holder 2A, the four stoppers 43 face the four corners of the bottom frame portion 21A of the another holder 2A. As a result, it is possible to prevent the position of the other holder 2A from deviating from the position of the holder 2A.

  As described above, according to the present embodiment, the object to be processed 100 as the ring member is in a state in which the opening 100c of the object to be processed 100 is erected sideways and the opening 100c has the first opening. Plural pieces are arranged so as to face the arrangement direction E1. Further, the positions of two objects 100 to be processed adjacent to the first arrangement direction E1 are displaced from each other in the second arrangement direction E2. According to this configuration, the fluid can more smoothly pass through the space surrounded by the inner peripheral surface 100b of each processing target 100. Therefore, for example, a medium (fluid) for heat treatment, such as carburizing gas in the carburizing process, oil and nitrogen gas in the quenching process, can be more smoothly supplied to the space on the inner peripheral side of the object 100 to be processed. can do. Further, in each of the objects to be processed 100, it is possible to suppress variations in the supply degree of the medium at the inner peripheral portion and the outer peripheral portion. As a result, it is possible to further reduce the degree of variation in the heat treatment of each object 100 to be processed. Further, it is possible to further reduce the degree of variation in heat treatment among the plurality of objects to be processed 100. Therefore, the heat treatment qualities such as the surface hardness and the internal hardness of each object 100 can be made more uniform. Further, the medium for heat treatment is not smoothly supplied to the inner peripheral side of the object to be processed 100 by increasing the interval between the objects to be processed 100 in the first arrangement direction E1. Therefore, the space required for heat-treating the object 100 to be processed can be further reduced. As a result, more objects to be processed 100 can be placed in the holder 2A placed in the heat treatment furnace 5 at once. Therefore, more objects 100 to be processed can be heat-treated at one time. As described above, when heat-treating the object 100 to be processed made of metal, it is possible to reduce variations in heat treatment quality, and it is possible to heat-treat more objects 100 to be processed at once.

  Further, according to the present embodiment, both the first arrangement direction E1 and the second arrangement direction E2 are horizontal directions. According to this configuration, the space occupied by each of the workpieces 100 in the upper and lower sides can be made narrower. Therefore, more objects to be processed 100 can be arranged at once in the limited space for heat treatment.

  Further, according to the present embodiment, the two objects to be processed 100 adjacent to each other in the first arrangement direction E1 are arranged such that the end surfaces 100d, 100d facing each other are in contact with each other. According to this configuration, each object 100 to be processed can function as a spacer that defines the position of the object 100 to be processed. For example, in the three processed objects 100 arranged in the first arrangement direction E1, the first processed object 100 and the third processed object 100 in the first arranged direction E1 sandwich the second processed object 100. It will be. With such a configuration, the second processed object 100 sets the interval between the first processed object 100 and the third processed object 100 to be the same as the thickness TH1 of the second processed object 100. it can. As a result, a large number of objects 100 to be processed can be arranged more evenly along the first arrangement direction E1. Further, since the plurality of objects to be processed 100 can be erected while being in contact with each other, these objects to be processed 100 can be autonomously erected. Therefore, it is not necessary to separately provide a support member for supporting the object 100 to be processed so as not to fall. This allows the objects 100 to be processed to be arranged at a higher density. Therefore, more objects to be processed 100 can be arranged at once in a limited space.

  Further, according to the present embodiment, the objects 100 to be processed in the first object row 41 and the objects 100 to be processed in the second object row 42 are alternately arranged in the first arrangement direction E1. With this configuration, the objects to be processed 100 can be arranged in a zigzag pattern. Thereby, even when the space for arranging the object 100 to be processed is small, the medium can be more evenly distributed to the inner peripheral portion and the outer peripheral portion of each object 100 to be processed. Further, the object to be processed 100 can be arranged more efficiently. As a result, more objects 100 to be processed can be heat-treated more uniformly in a limited space.

  Further, according to the present embodiment, when the object rows 41 and 42 are viewed from the first arranging direction E1, the object objects 100 are not the second object objects 100 in the adjacent object object rows and are the second object objects. Regions having a length equal to or smaller than half the outer diameter of the object to be processed 100 are arranged so as to overlap with each other in the direction E2. According to this configuration, when viewed from the first arrangement direction E1, one object 100 to be processed and the one object 100 to be processed are both the object 100 to be processed which is adjacent to both sides in the second arrangement direction E2. And can be overlaid. Thereby, the object 100 to be processed can be more efficiently arranged in the limited space for arranging the object 100 to be processed. As a result, more objects 100 to be processed can be heat-treated at once in a limited space.

  Further, according to the present embodiment, the support members 27A of the receiving portions 26A of the holder 2A are arranged so as to be arranged at the predetermined pitch P1 in the second arrangement direction E2. Further, the workpiece 100 is configured to be supported by the pair of support members 27A, 27A adjacent to the second arrangement direction E2. With this configuration, a simple configuration in which the pair of support members 27A and 27A support the object 100 to be processed can realize a configuration in which the object 100 to be processed is stably supported without falling. Further, since the object to be processed 100 is not suspended, it is possible to suppress the generation of tensile stress in the object to be processed 100 during the heat treatment of the object to be processed 100. As a result, it is possible to prevent tensile stress from being generated in the object 100 to be processed as residual stress. Therefore, the mechanical strength of the object to be processed 100 can be further increased.

  Moreover, according to this embodiment. The pair of vertical frame portions 22A and 23A of the holder 2A are each formed in a mesh shape. According to this configuration, since the vertical frame portions 22A and 23A can receive the object 100 to be processed, it is possible to prevent the object 100 to be processed from falling. Further, since the vertical frame portions 22A to 25A are formed in a mesh shape, the medium for heat treatment can be smoothly introduced from the outer side to the inner side of the holder 2A through the vertical frame portions 22A to 25A. Thereby, the heat treatment of the object to be processed 100 can be performed more uniformly.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. The present invention can be modified in various ways within the scope of the claims.

  (1) In the above embodiment, the heater unit 6 has been described as an example in which the object to be processed 100 is heated at least between the A1 transformation point and the A3 transformation point. In this regard, the heater unit 6 may heat the object 100 to be processed not only between the A1 and A3 transformation points but also in other temperature ranges.

  (2) Further, in the above-described embodiment, the mode in which the electrothermal heater unit is used as the heat source has been described as an example. However, this need not be the case. For example, as the heat source, a gas type tube burner, an electric resistance heating type heater having a heating element embedded in the wall, or the like may be used.

  (3) In addition, in the above-described embodiment, the holders 2 and 2A hold the object to be processed 100 in a state where the axial direction D1 of the object to be processed 100 is horizontal. .. However, this need not be the case. For example, as shown in each of the modified examples of FIGS. 14 and 15, the object to be processed 100 is arranged in an upright posture, and is arranged such that the axial direction D1 is a direction inclined with respect to the horizontal plane. It may have been done.

  In the modified example shown in FIG. 14, the holder 2 is provided with an inclined posture support portion 29. The inclined posture support portion 29 is a rod-shaped member whose both ends are supported by the left and right vertical frame portions 24 and 25 of the holder 2. The object 100 to be processed is received by the tilted posture support portion 29 in a posture tilted with respect to the horizontal plane. More specifically, the lower part of the object 100 to be processed is received by the support member 27, and the upper position of the object 100 is inclined with respect to the position of the lower part of the object 100 in the main radiation direction D2. The object to be processed 100 is arranged in a state of being brought close to the support portion 29 side. At this time, in a plan view, that is, when the holder 2 is viewed from above, the axial direction D1 and the main radiation direction D2 may coincide with each other or may be inclined to each other.

  When the holder 2 is viewed from above, when the axial direction D1 (thickness direction D3) and the main radiation direction D2 coincide with each other, in a side view, the axial direction D1 (thickness direction D3) and the main radiation direction D2 The inferior angle formed is the inferior angle θ1.

  When the holder 2 is viewed from above, when the axial direction D1 (thickness direction D3) is inclined with respect to the main radiation direction D2, the plan view (more accurately, from the direction orthogonal to the axial direction D1 In a plan view), the inferior angle formed by the axial direction D1 and the main radiation direction D2 is the first inferior angle θ1. Further, in side view, the inferior angle formed by the axial direction D1 and the main radiation direction D2 is the second inferior angle θ1. In this case, both the first inferior angle θ1 and the second inferior angle θ1 are set to be 45 ° or less (including zero).

  In the modification shown in FIG. 15, the entire holder 2 is arranged so as to be inclined with respect to the horizontal direction. In this case, the holder 2 is supported by the block-shaped tilt posture support member 30 fixed to the pedestal 7, and thus the tilt posture is maintained.

  Note that the same configuration as the configuration of the holder 2 shown in FIGS. 14 and 15, that is, the configuration in which the workpiece 100 in the standing posture is arranged in an inclined posture with respect to the horizontal direction may be adopted for the holder 2A. ..

  According to the modified examples shown in FIGS. 14 and 15 described above, the axial direction D1 (thickness direction D3) of the object to be processed 100 is a direction inclined with respect to the horizontal direction. According to this configuration, the plurality of objects to be processed 100 can be more appropriately arranged in a state in which the weight balance of the plurality of objects to be processed 100 as a whole is taken into consideration.

  (4) In addition, in the above-described embodiment, the case where the corresponding support members 27 and 27A of the holders 2 and 2A are fixed to the corresponding bottom frame portions 21 and 21A has been described as an example. However, this need not be the case. For example, in each of the holders 2 and 2A, the support members 27 and 27A may be configured to be rotatable with respect to the bottom frame portions 21 and 21A. In this case, the support members 27, 27A are configured to be rotatable about the central axis of the support members 27, 27A. As a result, the workpiece 100 placed on the support members 27, 27A can be rotated around the central axis B3 of the workpiece 100. Thereby, the stress generated in each part of the object to be processed 100 can be made more uniform, so that the distortion generated in the object to be processed 100 can be further reduced. Further, since the degree of exposure of the inner peripheral portion and the outer peripheral portion of the object 100 to the medium can be made more uniform, the heat treatment quality can be made more uniform.

  (5) Further, in each of the above-described embodiments, the configuration in which the subordination angle θ1 formed by the axial direction D1 (thickness direction D3) and the main radiation direction D2 is defined has been described. It is possible to arbitrarily combine configurations other than this inferior angle.

  (6) In addition, in the above-described second embodiment, an example has been described in which the first processed object row 41 and the second processed object row 42 are alternately arranged in the second alignment direction E2. However, this need not be the case. In the second embodiment, it is sufficient that the two processing objects 100 adjacent to each other in the first arrangement direction E1 are displaced from each other in the second arrangement direction E2, and it is not necessary to dispose the illustrated processing object 100. Good.

  (7) Further, in each of the above-described embodiments, the mode in which the ring-shaped object to be processed 100 is heat-treated has been described as an example. However, this need not be the case. For example, the present invention may be applied to heat treatment of an object to be processed having a cylindrical shape other than the cylindrical shape. FIG. 16A is a plan view for explaining another example of the object to be processed, and is an enlarged view of the holder 2 and the object to be processed 100B in the heat treatment apparatus 1. FIG. 16B is a cross-sectional view of the object to be processed 100B seen from the front, and also shows a part of the holder 2. FIG. 16C is a cross-sectional view of the holder 2 and the object to be processed 100B, showing a state in which the object to be processed 100B is viewed from the side.

  16A, 16B, and 16C, the object to be processed 100B is, for example, an outer ring of a constant velocity joint, and is a drive for transmitting the output from a prime mover such as an engine and an electric motor to a drive wheel in an automobile. Provided on the shaft. The object 100B to be processed has an annular portion 50B and an end wall 51B formed at one end of the annular portion 50B. The annular portion 50B has a cylindrical shape extending in the axial direction D1 (thickness direction D3) of the object to be processed 100B, and has a polygonal shape in a cross section orthogonal to the axial direction D1 (thickness direction D3). In the present embodiment, the annular portion 50B is formed into a substantially regular hexagonal cross section. The annular portion 50B is formed in a shape in which the contour of the outer peripheral portion surrounding the central axis B3 of the annular portion 50B projected on a plane perpendicular to the axial direction D1 is polygonal (hexagonal in the present embodiment). Can also be said.

  In addition, the annular portion 50B may be formed in a polygonal shape other than the hexagonal shape. As an example of the polygon of the shape of the annular portion 50B, a triangle, a quadrangle, an octagon, etc. can be exemplified. When viewed in the axial direction D1, each top portion 52B of the annular portion 50B is formed in an arc shape that is convex outward in the radial direction of the central axis B3B of the annular portion 50B. The inner side surface 52aB of each top portion 52B includes a raceway surface for the spherical rolling element 53B to roll along the axial direction D1, and is formed in a linear groove shape extending along the axial direction D1. The shape of the inner peripheral portion and the shape of the outer peripheral portion of the annular portion 50B are formed similar to each other. Note that the polygonal corners of the annular portion 50B do not necessarily have to be sharp, and may have some roundness. An opening is formed in the end wall 51B formed at one end of the annular portion 50B. A shaft (not shown) is connected to this opening.

  The object 100B to be processed is heat-treated by the heat treatment apparatus 1 in a state where the object 100 to be processed is arranged in the holder 2 in the same manner as the object 100 is arranged in the holder 2. That is, the object 100B to be processed is arranged in the holder 2 so as to have the axial direction D1 that coincides with the axial direction D1 of the object 100 to be processed when the object 100 to be processed is arranged. As a result, the object 100B to be processed is supported by the first support portion 31 and the second support portion 32, similarly to the object 100 to be processed. Further, the object 100B to be processed is placed on the holder 2 so that the subordination angle θ1 formed by the axial direction D1 (that is, the thickness direction D3) of the object 100 to be processed and the main radiation direction D2 is 45 ° or less (including zero). Are placed.

  The object 100B to be processed may be heat-treated while being supported by the holder 2A as shown in FIG. 16D. In this case, the mode of arrangement of the objects to be processed 100B in the holder 2A is the same as the mode of arrangement of the objects to be processed 100 in the holder 2A shown in FIG. 13, and a large number of object lines 41 and a large number of objects to be processed. Rows 42 are formed. Instead of the object 100 to be processed, the object 100B to be processed is arranged in each of the object rows 41 and 42.

  Further, as shown in FIG. 16E or FIG. 16F, the object to be processed 100B is arranged in an upright posture, and the axial direction D1 (thickness direction D3) is a direction inclined with respect to the horizontal plane, It may be arranged. In the modification shown in FIG. 16E, the object to be processed 100B is received by the pair of inclined posture support parts 29B and 29B in a posture inclined with respect to the horizontal plane. In this case, the arrangement mode of the object 100B to be processed in the holder 2 is the same as the arrangement mode of the object 100 to be processed in the holder 2 shown in FIG. In addition, in the modification shown in FIG. 16F, the entire holder 2 is arranged so as to be inclined with respect to the horizontal direction. In this case, the holder 2 is supported by the block-shaped tilt posture support member 30 fixed to the pedestal 7, and thus the tilt posture is maintained. Note that the same configuration as the configuration of the holder 2 shown in FIGS. 16E and 16F, that is, the configuration in which the object 100 to be processed in the standing posture is arranged in an inclined posture with respect to the horizontal direction may be adopted for the holder 2A. ..

  According to the above configuration, in the object to be processed 100B having the annular portion 50B formed in a polygonal annular shape, the degree of temperature change of each portion can be made more uniform. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  Further, according to the above configuration, in the annular portion 50B of the object to be processed 100B, the inner peripheral portion formed in a shape similar to the shape of the outer peripheral portion is provided. With this configuration, in the annular portion 50B of the object to be processed 100B that is formed in an annular shape and has a substantially uniform thickness, the degree of temperature change in each portion can be made more uniform. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  Further, when the object to be processed 100B is an outer ring of a constant velocity joint, this outer ring is a component forming a raceway surface of a rolling element such as a steel ball and is required to have excellent roundness and rolling fatigue life. .. With respect to the accuracy and life required for the outer ring of such a constant velocity joint, high roundness and rolling fatigue life can be obtained.

  Although the object 100B to be processed has been described as an example in which it is a constant velocity joint, this does not have to be the case. The object 100B to be processed may be used as an outer ring of an intermediate shaft of a steering shaft or the like.

  (8) Further, the present invention may be applied to the heat treatment of the ring-shaped object to be processed 100C instead of the object to be processed 100. FIG. 17 is a schematic perspective view of the processing object 100C.

  With reference to FIGS. 1 to 5 and 17, the object to be processed 100C is, for example, a piston used in a lockup mechanism of a hydraulic torque converter used in an automatic transmission of an automobile, and is formed in a ring shape. There is. Such an object to be processed 100C is formed in a disk shape (plate shape), and is arranged in the holder 2 in the same manner as the object 100 is arranged in the holder 2 and the heat treatment apparatus 1 Heat treated by. In this modification, the through hole is formed in the center of the object to be processed 100C, but this need not be the case. For example, a circular object having a shape in which the through hole is closed may be used.

  One side surface 100h of the object to be processed 100C is configured to transmit power from the prime mover to the transmission by frictionally coupling by being pressed against a friction material provided in the lockup mechanism by hydraulic pressure. Therefore, the one side surface 100h of the object to be processed 100C as the piston is required to have high wear resistance. Therefore, the desired wear resistance is ensured by subjecting the one side surface 100h to heat treatment such as quenching. The one side surface 100h is required to have good flatness in order to stably frictionally engage the friction material. However, in general, when quenching is performed, there occurs a problem that the flatness of the one side surface 100h is deteriorated due to heat treatment distortion caused by surface hardening. However, the object 100C to be processed by the heat treatment apparatus 1 has such a small distortion that it is possible to prevent the above-mentioned problems from becoming a problem.

  (9) Further, in each of the above-described embodiments, the case where the objects 100, 100B, and 100C to be processed including the inner peripheral portion and the outer peripheral portion having similar shapes are heat-treated has been described as an example. However, this need not be the case. For example, the present invention may be applied to the heat treatment of the object to be processed 100D in which the shape of the inner peripheral portion is not similar to the shape of the outer peripheral portion. FIG. 18 is a front view for explaining another example of the object to be processed and shows a cross section, which shows an enlarged main part of the holder 2 and the object to be processed 100D in the heat treatment apparatus 1.

  With reference to FIG. 3 and FIG. 18, the object to be processed 100D is, for example, a cutting blade, and is configured to cut an object to be cut by being rotationally driven by a rotating shaft (not shown). .. The object to be processed 100D is a plate-shaped metal member having an annular portion as a portion including the shape of at least a part of the annular portion. In the present embodiment, the object 100D to be processed is provided as a portion including the entire annular portion. A connection portion 54D that is integrally rotatably connected to the rotation shaft is formed on the inner peripheral portion of the object to be processed 100D. The connecting portion 54D is a spline or a serration. The outer peripheral surface of the object to be processed 100D includes a circular portion 55D and a protruding portion 56D protruding from the circular portion 55D outward in the radial direction of the central axis B3 of the object to be processed 100D. A plurality of protrusions 56D (five in the present embodiment) are provided at equal pitches in the circumferential direction of the object to be processed 100D. A blade portion 57D is formed at the tip of each protruding portion 56D.

  Such an object to be processed 100D is formed in a disk shape (plate shape), and is arranged in the holder 2 in the same manner as the object 100 to be processed is arranged in the holder 2 and the heat treatment apparatus 1 Heat treated by. The blade portion 57D on the outer peripheral portion of the object to be processed 100D is required to have high wear resistance. Therefore, the blade portion 57D is subjected to heat treatment such as quenching to ensure desired wear resistance. The blade portion 57D is required to have good shape accuracy in order to accurately cut the object to be cut. However, in general, when quenching is performed, the shape of each blade 57D becomes non-uniform due to heat treatment distortion caused by surface hardening. However, such a distortion is small in the object to be processed 100D that has been subjected to the heat treatment by the heat treatment apparatus 1, and it is possible to suppress the above problems from becoming a problem.

  Thus, in the object to be processed 100D in which the blade portion 57D is formed on the outer peripheral portion, the degree of temperature change of each portion including the outer peripheral portion can be made more uniform. As a result, it is possible to form a metal part having a small distortion.

  (10) The objects to be processed 100C and 100D may be supported by the holder 2A as shown in FIG. In this case, the arrangement mode of the objects 100C and 100D to be processed in the holder 2A is the same as the arrangement mode of the object 100 to be processed in the holder 2A shown in FIG. Further, as shown in FIG. 14 or FIG. 15, the objects to be treated 100C and 100D are arranged in an upright posture, and the axial direction D1 (thickness direction D3) is a direction inclined with respect to the horizontal plane. It may be arranged in. In this case, the arrangement mode of the objects 100C and 100D to be processed in the holder 2 is the same as the arrangement mode of the object 100 to be processed in the holder 2 shown in FIG. 14 or FIG. Note that the same configuration as the configuration of the holder 2 shown in FIG. 14 or FIG. 15, that is, the configuration in which the workpieces 100C and 100D in the standing posture are arranged in an inclined posture with respect to the horizontal direction is adopted for the holder 2A. Good.

  (11) The object to be processed 100D described above has an undulating portion (spline or serration) that is integrally rotatably connected to the rotation shaft on the inner peripheral portion of the object to be processed 100D. However, this need not be the case. For example, the heat treatment may be performed in a state where the objects to be processed 100E, 100F, 100G, 100H shown in FIGS. 19A to 19C are arranged in the holder 2.

  FIG. 19A is a plan view for explaining another example of the object to be processed, and shows the holder 2 and the objects to be processed 100E, 100F, 100G, 100H in the heat treatment apparatus 1 in an enlarged manner. FIG. 19B is a cross-sectional view of the objects to be processed 100E, 100F, 100G, 100H seen from the front, and a part of the holder 2 also holds the objects to be processed 100E, 100F, 100G by using the convex portion 67. The location is shown. FIG. 19C is a cross-sectional view of the objects to be processed 100E, 100F, 100G, 100H as seen from the front, and a part of the holder 2 also holds the objects to be processed 100E, 100F, 100G, 100H in the recess 68. Is shown in cross section.

  The objects 100E, 100F, 100G are blades for cutting weeds, for example, and are configured to cut the object to be cut by being rotationally driven by a rotary shaft (not shown). Each of the objects to be processed 100E, 100F, 100G is a plate-shaped metal member having an annular portion as a portion including the shape of at least a portion of the annular portion, and has a thickness of about several mm. In the present embodiment, each of the objects to be processed 100E, 100F, 100G is provided as an annular portion including the entire annular shape. A through hole portion 60 is formed on the inner peripheral portion of each of the objects to be processed 100E, 100F, 100G. The inner peripheral surface of the through hole portion 60 is formed in a circular shape.

  Corresponding blade portions 61E, 61F, 61G are formed on the outer peripheral portion of each of the workpieces 100E, 100F, 100G. The blade portions 61E are provided at two locations at equal intervals in the circumferential direction of the through hole portion 60 in the object to be processed 100E, and extend in the radial direction of the through hole portion 60. The blade portions 61F are provided at three locations at equal intervals in the circumferential direction of the through hole portion 60 in the object to be processed 100F, and extend in the radial direction of the through hole portion 60. The blade portions 61G are formed by making the outer peripheral portion of the disk-shaped object to be processed 100F into a serrated shape, and are arranged in the circumferential direction of the through-hole portions 60 at equal pitches.

  The object to be processed 100H is, for example, a link plate of a power transmission chain, and is configured to be connected to another link plate via a pin (not shown). The object to be processed 100H is a plate-shaped metal member provided with the annular portions 62H and 63H as a portion including at least a part of the annular shape, and has a thickness of about several mm. In the present embodiment, the object to be processed 100H is formed in a figure eight shape and has a first annular portion 62H and a second annular portion 63H.

  The first annular portion 62H is provided as a half portion of the object to be processed 100H. The first annular portion 62H is a portion including a part of an annular shape, and includes a portion of the annular shape that is larger than 180 ° and smaller than 360 ° when viewed from the axial direction D1 of the object to be processed 100H. .. The second annular portion 63H is provided as a half portion of the workpiece 100H. The second annular portion 63H is a portion including a part of an annular shape, and includes a portion of the annular shape that is larger than 180 ° and smaller than 360 ° when viewed from the axial direction D1 of the object to be processed 100H. .. The first annular portion 62H and the second annular portion 63H are formed in symmetrical shapes.

  A plurality of holes 64H and 65H are formed in the object to be processed 100H. The hole portion 64H is a circular through hole arranged concentrically with the outer peripheral edge portion of the first annular portion 62H. The hole portion 65H is a circular through hole that is arranged concentrically with the outer peripheral edge portion of the second annular portion 63H. Pins (not shown) are inserted into these holes 64H and 65H. The central axis B3 of the object 100H to be processed passes through, for example, the centroid of the object 100H to be processed when viewed in the axial direction D1, and is parallel to the central axes of the holes 64H and 65H.

  Each of the processing objects 100E, 100F, 100G, and 100H as described above is arranged in the holder 2 and heat-treated by the heat treatment apparatus 1 in the same manner as the processing object 100 is arranged in the holder 2. Each of the workpieces 100E, 100F, 100G, 100H has an inferior angle θ1 formed between the axial direction D1 of each of the workpieces 100E, 100F, 100G, 100H (that is, the thickness direction D3) and the main radiation direction D2. It is arranged in the holder 2 so that the angle is 45 ° or less (including zero).

  Each of the objects to be processed 100E, 100F, 100G, 100H is formed in a relatively thin plate shape and may not be able to stand up autonomously. Therefore, when each of the objects to be processed 100E, 100F, 100G, 100H is arranged in the holder 2, each supporting member 27 of the receiving portion 26 of the holder 2 is provided with the supporting portion 66.

  The support portion 66 includes a concave portion 67 that forms either the first receiving portion 31 or the second receiving portion 32 of the support member 27, or a convex portion 68 provided on the support member 27. The recess 67 supports the workpieces 100E, 100F, 100G so that the workpieces 100E, 100F, 100G are in an upright posture by fitting with the outer peripheral portion of any of the workpieces 100E, 100F, 100G, 100H. When the recesses 67 support the objects to be processed 100E, 100F, 100G, 100H, the outer peripheral portion of the recesses 67 is formed, for example, in a circular sectional shape orthogonal to the axial direction D1, and the corresponding objects to be processed 100E, The 1st support part 31 and the 2nd support part 32 which support 100F, 100G, 100H are formed.

  The convex portion 68 is provided on the outer peripheral portion of the support member 27. The convex portion 68 sandwiches each of the workpieces 100E, 100F, 100G in the axial direction D1 (thickness direction D3) at a portion of the support member 27 where the concave portion 67 is not provided. The 100F, 100G, and 100H are supported in an upright posture.

  The holder 2 may hold only the same type (for example, the processed object 100E) among the processed objects 100E, 100F, 100G, 100H, or different types (for example, the processed objects 100E, 100F, 100G). , 100H may be held in a mixed state.

  (12) Note that each of the objects to be processed 100E, 100F, 100G, 100H may be heat-treated while being supported by the holder 2A, as shown in FIG. 19D. In this case, the arrangement mode of the processing objects 100E, 100F, 100G, 100H in the holder 2A is the same as the arrangement mode of the processing object 100 in the holder 2A shown in FIG. 41 and a large number of workpiece rows 42 are formed. Instead of the workpiece 100, any of the workpieces 100E, 100F, 100G, and 100H is arranged in each of the workpiece rows 41 and 42. In this case, since the objects to be processed 100E, 100F, 100G, 100H are arranged so as to support each other, the concave portion 67 and the convex portion 68 are unnecessary.

  Further, as shown in FIG. 19E or 19F, each of the objects to be processed 100E, 100F, 100G, 100H is arranged in an upright posture, and the axial direction D1 (thickness direction D3) is inclined with respect to the horizontal plane. They may be arranged in the same direction. In the modification shown in FIG. 19E, each of the objects to be processed 100E, 100F, 100G, 100H is received by the tilted posture support portion 29E in a posture tilted with respect to the horizontal plane. In the modification shown in FIG. 19E, the entire holder 2 is arranged so as to be inclined with respect to the horizontal direction. Note that the same configuration as the configuration of the holder 2 shown in FIGS. 19E and 19F, that is, the configuration in which each of the workpieces 100E, 100F, 100G, and 100H in the standing posture is arranged in an inclined posture with respect to the horizontal direction is a holder. It may be adopted for 2A.

  According to this modification, in the objects to be treated 100E, 100F, 100G having blade portions 61E, 61F, 61G formed on the outer peripheral portion, such as a cutter blade used for an engine cutter, the temperature change of each portion including the outer peripheral portion is changed. The degree can be made more even. As a result, it is possible to form a metal part having a small distortion.

  Moreover, according to this modification, a plurality of holes 64H and 65H are formed in the object 100H to be processed. With this configuration, in the workpiece 100H such as a chain link plate in which the plurality of holes 64H and 65H are formed, the degree of temperature change of each part including the peripheral portions of the plurality of holes 64H and 65H is made more uniform. it can. As a result, it is possible to form a metal component having a small distortion such as elliptic distortion.

  (13) Further, in each of the embodiments and the modified examples, the form in which the objects to be processed 100, 100B to 100H are endless rings is described as an example. However, this need not be the case. For example, the present invention may be applied to heat treatment of an object to be processed formed in a shape including a part of a ring shape such as a crescent shape or a semicircular shape.

  (14) Further, in each of the embodiments and the modifications, the objects 100, 100B to 100H to be processed have been described as an example in which they are supported from below. However, this need not be the case. For example, for the objects to be processed 100, 100B to 100H, the objects to be processed 100, 100B to 100H are hung in the heat treatment furnace 5 using a bar configured to receive the inner peripheral surface, and the objects to be processed are The objects 100 and 100B to 100H may be heat-treated. Also in this case, the strain of the objects to be processed 100, 100B to 100H can be further reduced.

<Distortion by type of placement of object to be processed>
Example 1 and Comparative Example 1 were produced by carburizing a ring-shaped metal workpiece using a heat treatment apparatus having the same configuration as the heat treatment apparatus 1 described in the first embodiment. The manufacturing conditions of Example 1 and Comparative Example 1 are different in the following points.

Example 1: The inferior angle formed by the axial direction of the object to be processed and the main radiation direction was set to zero. That is, Example 1 was the object to be heat-treated in the state where the axial direction of the object to be processed coincides with the main radiation direction.
Comparative Example 1: The inferior angle formed by the axial direction and the main radiation direction was 90 °. More specifically, Comparative Example 1 was obtained by performing heat treatment in a state in which the object to be processed was placed horizontally so that the axial direction of the object to be processed was oriented in the vertical direction. Note that, except for the inferior angle, Example 1 and Comparative Example 1 are heat-treated under the same conditions.

  140 pieces of Example 1 and 120 pieces of Comparative Example 1 were produced. Then, the elliptic strain (elliptic strain) was measured for each of Example 1 and Comparative Example 1. Specifically, for each of Example 1 and Comparative Example 1, the difference between the diameter at the location having the largest diameter and the diameter at the location having the smallest diameter is calculated as the elliptic strain amount. Was measured as. Then, the average value of the elliptic strain amounts in the plurality of comparative examples 1 was defined as the reference strain amount. Then, the ratio of the strain amount to the reference strain amount is defined as the elliptic strain ratio. The results are shown in Fig. 20. The vertical axis of FIG. 20 represents the elliptic distortion ratio.

  As shown in FIG. 20, in a plurality of comparative examples 1, when the elliptic strain amount was the largest, the elliptic strain ratio as a ratio of the strain amount to the reference strain amount reached 200%. On the other hand, the average value of the elliptic strain amounts in the plurality of Examples 1 was only about 60% of the reference strain amount. In addition, the elliptic strain ratio was only about 110% even when the elliptic strain amount was the largest among the plurality of Examples 1. That is, Example 1 was able to reduce the elliptic distortion to about half as compared with Comparative Example 1. As described above, it was proved that Example 1 can make the elliptic distortion extremely small.

<About the relationship between the inferior angle formed by the axial direction of the object to be processed and the main radiation direction and strain>
In addition to Example 1, Example 2, Example 3, and Comparative Example 2 were prepared. In addition, Example 1, Example 2, Example 3, and Comparative Example 2 have the same configuration except that the inferior angle formed by the axial direction of the object to be processed and the main radiation direction during heat treatment is different. Have In each of the example 1, the example 2, the example 3, and the comparative example 2, the heat treatment is performed in a vertical posture (a standing posture). Specifically, it is as follows.
Example 1: Inferior angle = 0 °
Example 2: Inferior angle = 30 °
Example 3: Inferior angle = 45 °
Comparative Example 2: Inferior angle = 60 °

  Five pieces of Example 2, five pieces of Example 3, and five pieces of Comparative Example 2 were produced. Then, the elliptic distortion was measured for each of Example 2, Example 3, and Comparative Example 2. The results are shown in Fig. 21. The display method of the elliptic distortion is the same as the display method shown in FIG. The vertical axis in FIG. 21 indicates the elliptic distortion ratio, as in the vertical axis in FIG. In addition, about Example 1, the same result as the result shown in FIG. 20 is shown.

  As shown in FIG. 21, among the plurality of comparative examples 2, when the elliptic strain amount was the largest, the elliptic strain ratio reached about 180%. Regarding the average value of the elliptic strains in Comparative Examples 2, the elliptic strain ratio was about 90%. On the other hand, with respect to the maximum value of the elliptic distortion amount in the plurality of Examples 3, the elliptic distortion ratio was only about 130%. In addition, the elliptic strain ratio was only about 80% with respect to the average value of the elliptic strain amounts in the plurality of Examples 3. Further, with respect to the maximum value of the elliptic strain amount in the plurality of Examples 2, the elliptic strain ratio was only about 120%. Further, the elliptic strain ratio was only about 70% with respect to the average value of the elliptic strain amounts in the plurality of Examples 2. Further, as described above, the elliptic distortion ratio was only about 110% with respect to the maximum value of the elliptic distortion amount in the plurality of Examples 1. Further, the elliptic strain ratio was only about 60% with respect to the average value of the elliptic strain amounts in the plurality of Examples 1.

  As described above, it was proved that the smaller the inferior angle formed by the axial direction of the object to be processed and the main radiation direction, the smaller the elliptic distortion. When the straight line F1 passing through the maximum elliptic strain ratio in each of Examples 1 to 3 is drawn in FIG. 21, the maximum value of the elliptic strain ratio in Comparative Example 2 is located far above the straight line F1. Become. That is, it was proved that Examples 1 to 3 in which the inferior angle formed by the axial direction of the object to be processed and the main radiation direction was 45 ° or less had extremely small elliptic distortion.

<Relationship between carbon potential and strain in furnace atmosphere>
Examples 4 to 6 and Comparative Example 3 were produced by varying the carbon potential in the atmospheric gas during the heat treatment of the object to be treated. The heat treatment conditions for Examples 4 to 6 and Comparative Example 3 were the same except for the carbon potential. Specifically, the carbon potentials during heat treatment in Examples 4 to 6 and Comparative Example 3 are as follows.

Example 4: 0.6%
Example 5: 0.8%
Example 6: 1.0%
Comparative Example 3: 1.4%

  Ten pieces of Example 4, ten pieces of Example 5, ten pieces of Example 6, and ten pieces of Comparative Example 4 were produced. Then, the elliptic distortion was measured for each of Example 4, Example 5, Example 6, and Comparative Example 3. The results are shown in Fig. 22. The display method of the elliptic distortion is the same as the display method shown in FIG. The vertical axis in FIG. 22 indicates the elliptic distortion ratio, as in the vertical axis in FIG.

  As shown in FIG. 22, when the elliptic strain amount was the largest among the plurality of comparative examples 3, the elliptic strain ratio reached about 110%. On the other hand, regarding the average value of the elliptic strain amounts in the plurality of Examples 6, the elliptic strain ratio was only about 50%. Further, even in the case where the elliptic strain amount was the largest among the plurality of Examples 6, the elliptic strain ratio was only about 90%. Moreover, the elliptic strain ratio was only about 40% with respect to the average value of the elliptic strain amounts in the plurality of Examples 5. In addition, the elliptic strain ratio was only about 80% even when the amount of elliptic strain was the largest among the plurality of Examples 5. Further, the elliptic strain ratio was only about 55% with respect to the average value of the elliptic strain amounts in the plurality of Examples 4. In addition, the elliptic strain ratio was only about 95% even when the amount of elliptic strain was the largest among the plurality of Examples 4.

  As described above, in Examples 4 to 6 in which the carbon potential during the heat treatment is in the range of 0.6% to 1.0%, the elliptic strain ratio is less than 100% at the maximum, and the elliptic strain is extremely small. Was demonstrated. Particularly, it was proved that the elliptic strain was extremely small in Example 5 in which the carbon potential during the heat treatment was set to 0.8% which is substantially equal to 0.77% which is the carbon potential at the eutectoid point.

  INDUSTRIAL APPLICATION This invention can be widely applied as a manufacturing method of a metal component, and a heat processing apparatus.

1 Heat treatment device 2, 2A holder 6 Heater unit (heat source)
16 Heater tube (heating part)
31, 31A 1st support part 32, 32A 2nd support part 50B Annular part 57D Blade part 61E, 61F, 61G Blade part 62H, 63H Annular part 64H, 65H Plural hole parts 100, 100C, 100D, 100E, 100F, 100G. ， Processed objects (metal parts, annular parts)
100H Processed object (metal part)
100a Outer peripheral surface of object to be treated B3 Central axis of object to be treated Cp Carbon potential D1 Axial direction of object to be treated D2 Main radiation direction D3 Thickness direction TH1 Thickness θ1 Inferior angle θ2 Angle interval

Claims (16)

An object to be processed made of metal having an annular portion as a part including at least a part of the annular shape, and a heat source arranged outside the object to be radiated heat in a predetermined main radiation direction. An arranging step of arranging the heat source and the heat source to face each other, and arranging the object to be processed such that an inferior angle formed by the axial direction of the annular portion and the main radiation direction is 45 ° or less (including zero);
A heating step of heating the object to be processed using the heat source,
Including,
In the arranging step, the object to be processed is arranged between a plurality of heating units provided in the heat source, and is arranged in an upright posture, and the axial direction is along a horizontal direction, or A method for manufacturing a metal component, wherein the axial direction is a direction inclined with respect to the horizontal direction. A plate-shaped metal object to be processed having a predetermined thickness, and a heat source arranged outside the object to be processed and a heat source that radiates heat in a predetermined main radiation direction are opposed to each other, and An arrangement step of arranging the object to be processed such that an inferior angle formed by the thickness direction of the object to be processed and the main radiation direction is 45 ° or less (including zero);
A heating step of heating the object to be processed using the heat source,
Including,
In the arranging step, the object to be processed is arranged between a plurality of heating units provided in the heat source and arranged in an upright posture, and the thickness direction is along a horizontal direction or the A method of manufacturing a metal component, wherein the thickness direction is a direction inclined with respect to the horizontal direction. A method of manufacturing a metal component according to claim 1 or 2, wherein
In the arranging step, a plurality of the objects to be processed are arranged along the main radiation direction, a method for manufacturing a metal component. A method for manufacturing the metal component according to any one of claims 1 to 3, comprising:
In the arranging step, a predetermined holder supports the outer peripheral surface of the object to be processed from below, the method for manufacturing a metal component. A method of manufacturing a metal component according to claim 4,
The said holder supports the said to-be-processed object in the state of line contact or point contact, The manufacturing method of the metal components characterized by the above-mentioned. A method of manufacturing a metal component according to claim 1, wherein
In the arranging step, a predetermined holder supports the outer peripheral surface of the object to be processed from below,
The holder supports the object to be processed in line contact or point contact, and supports the outer peripheral surface of the object to be processed by a first support portion and a second support portion that are separated in the circumferential direction of the outer peripheral surface. And
A method for manufacturing a metal component, wherein an angular interval between the first support portion and the second support portion around a central axis of the object to be processed is set in a range of 20 ° to 60 °. A method for manufacturing the metal component according to any one of claims 1 to 6, comprising:
In the heating step, the object to be processed is heated in an atmosphere gas set to a carbon potential in the range of 0.6% to 1.0%. A method for manufacturing the metal component according to any one of claims 1 to 7, comprising:
The said heating step is performed at least between A1 transformation point and A3 transformation point of the said to-be-processed object, The manufacturing method of the metal components characterized by the above-mentioned. A method for manufacturing the metal component according to any one of claims 1 to 8, comprising:
In the heating step, the object to be processed is heated from the A1 transformation point to the A3 transformation point at a temperature rising rate in the range of 0.5 ° C./min to 10 ° C./min. Method. A method of manufacturing a metal component according to claim 1, wherein
The method for manufacturing a metal component, wherein the object to be processed has a tubular shape extending in the axial direction of the object to be processed, and a cross-section orthogonal to the axial direction has a polygonal shape. A method for manufacturing the metal component according to any one of claims 1 to 10, comprising:
The method for manufacturing a metal part, wherein the object to be processed is formed in a ring shape. A method for manufacturing the metal component according to any one of claims 1 to 11, comprising:
The method for manufacturing a metal component, wherein the object to be processed has an inner peripheral portion formed in a shape similar to the shape of the outer peripheral portion of the object to be treated. A method for manufacturing the metal component according to any one of claims 1 to 9,
A method of manufacturing a metal component, wherein a plurality of holes are formed in the object to be processed. A method for manufacturing the metal component according to any one of claims 1 to 9,
A method of manufacturing a metal component, wherein a blade portion is formed on an outer peripheral portion of the object to be processed. A heat source having a plurality of heating units and configured to radiate heat directed in a predetermined main radiation direction;
The object to be treated made of metal having an annular portion as a portion including at least a part of the annular shape and the heat source are opposed to each other so that the heat source is arranged outside the object to be treated, and the object to be treated is The object to be treated is arranged such that the inferior angle formed by the axial direction of the annular portion and the main radiation direction is 45 ° or less (including zero) in a state where the object to be treated is arranged between the plurality of heating units. A holder for placing,
Equipped with
The holder is configured to support the object to be processed in an upright posture, and the holder may be arranged such that the axial direction is along the horizontal direction or the axial direction is inclined with respect to the horizontal direction. A heat treatment apparatus, which is configured to support a processed material. A heat source having a plurality of heating units and configured to radiate heat directed in a predetermined main radiation direction;
A plate-shaped metal object having a predetermined thickness and the heat source are opposed to each other so that the heat source is arranged outside the object, and the object is a plurality of heating units. A holder for arranging the object to be processed such that an inferior angle formed by the thickness direction of the object to be processed and the main radiation direction is 45 ° or less (including zero) in a state in which the object is to be processed;
Equipped with
The holder is configured to support the object to be processed in an upright posture, and the holder may be arranged such that the thickness direction is along the horizontal direction or the thickness direction is inclined with respect to the horizontal direction. A heat treatment apparatus, which is configured to support a processed material.

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