JP2010018877A - Quenching apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost quenching apparatus and quenching method in which the unevenness of strain quantity of a work piece at the cooling time is reduced. <P>SOLUTION: In the quenching apparatus 10, a frame body 12 for supporting a plurality of work pieces W is shifted from a heating furnace and dipped into a cooling vessel 16 filled with cooling-liquid Q. The frame body 12 is provided with a grid-state bottom part 20 having uniform thermal capacity and of which the grid gaps are directed to the vertical direction in the lower projection range of the supported work pieces W. When the frame body 12 is descended into the cooling vessel 16, the bottom part 20 is touched to the cooling liquid Q proceeding to the work piece W. The grid gaps in the bottom part 20 are directed to the vertical direction and the cooling liquid Q is rapidly stirred over the whole body in the range where the bottom part 20 (that is, the lower projection range of the work pieces) passes. Since the work pieces W are touched to the cooling liquid after the stirring generated by the contact of the bottom part 20 is normalized, the unevenness of the strain quantities of the work pieces W set at the lowest step of the frame body 12 is suppressed equally as that of the work pieces W set at the steps other than the lowest step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a quenching apparatus and a quenching method for quenching a plurality of workpieces simultaneously. In particular, the present invention relates to a quenching apparatus and a quenching method that can reduce variations in workpiece distortion during quenching.

As one technique for enhancing the strength of a workpiece (mechanical part), a so-called quenching method is known in which the workpiece is heated and then rapidly cooled. In order to improve productivity, the quenching apparatus supports a plurality of workpieces with a frame, and heats and cools the entire frame. The quenching apparatus cools a plurality of workpieces by being submerged in a cooling tank filled with a cooling liquid (typically oil) together with the heated frame.
When a plurality of workpieces are supported by one frame and cooled, there may be a difference in the amount of distortion of the workpiece due to a difference in the cooling process depending on the position of the workpiece.
Patent Document 1 discloses a heat treatment bath (cooling tank) that makes the amount of strain uniform when cooling a workpiece. The heat treatment bath has detection means for detecting the local cooling performance of the workpiece, and a plurality of jet outlets capable of adjusting the jet flow rate or jet direction of the coolant. The heat treatment bath controls the jet outlet based on the detection result of the detection means to equalize the cooling performance of the coolant.
Patent Document 1 describes that a method of arranging a dummy member is known so that the cooling performance in the bathtub is uniform (Patent Document 1, paragraph 0004).

JP-A-7-157823

The method disclosed in Patent Document 1 requires a complicated cooling tank, and thus costs increase. Further, Patent Document 1 describes that a method of arranging dummy members is known, but it is not certain how the dummy members can be arranged to make the cooling performance uniform.
The present invention has been created in view of the above problems. An object of the present invention is to provide a quenching apparatus and a quenching method that reduce variations in the amount of workpiece distortion during cooling while being low in cost.

  The inventors have found a phenomenon that when a work group is arranged in a frame over a plurality of stages in the vertical direction and submerged in a cooling tank, the variation in distortion amount of the work group arranged at the bottom stage is larger than other stages. I found it. This phenomenon is considered to be caused by the fact that the cooling liquid begins to be violently disturbed at the moment when the heated work is submerged in the cooling tank in which the cooling liquid is in a gentle state. It is considered that when the state of the coolant becomes steady after the initial transition period of the disturbance, the cooling performance is globally uniformized in the cooling tank, and as a result, the variation in the strain amount of the workpiece group becomes small except in the lowermost stage. The That is, the degree of variation in the amount of distortion of the work greatly depends on the change over time in the disturbance of the coolant that occurs in a short time from the moment when the heated work touches the coolant. The present invention was created based on such novel findings.

The quenching apparatus according to the present invention is embodied in a quenching apparatus that moves a frame body supporting a plurality of workpieces from a heating furnace and immerses it in a cooling tank filled with a coolant. The frame of the quenching apparatus has a grid-shaped bottom portion with a grid facing in the vertical direction and a uniform heat capacity in a downward projection area of a workpiece being supported.
In this quenching apparatus, the lattice-shaped bottom having a uniform heat capacity comes into contact with the coolant prior to the work. The bottom lattice is directed vertically, and the cooling liquid starts to be disturbed over the entire region through which the bottom passes (that is, the lower projection region of the workpiece). After the bottom has passed, when the workpiece comes into contact with the coolant, it is stabilized after the initial transition period. Since the work comes into contact with the cooling liquid after the disturbance of the cooling liquid becomes steady, the variation in the distortion amount of the work arranged at the lowermost stage of the frame can be suppressed to be equal to that of the work arranged at other than the lowermost stage.
The quenching apparatus includes a lattice-shaped bottom portion having a uniform heat capacity, thereby suppressing variations in the distortion amount of the workpiece. This quenching apparatus can be realized at a very low cost because it only adds a grid-like bottom. The uniform heat capacity at the bottom may be macroscopically uniform over the entire workpiece lower projection area even if the heat capacity is locally different.

  It is preferable that the heat capacity at the bottom of the frame body is substantially equal to the total heat capacity of a plurality of works dispersedly supported in the horizontal direction of the frame body. The coolant can be sufficiently disturbed between the time when the bottom part touches the coolant and the workpiece touches the coolant, and the temperature of the coolant does not rise excessively.

  The variation in the amount of distortion can be further suppressed by the cooling liquid flowing uniformly on the workpiece surface. Therefore, it is preferable that the frame body is provided with fins for turning the coolant flowing from the lower side to the upper side of the work around the work when immersed in the cooling tank. Or it is preferable that the frame is provided with the partition plate surrounding the circumference | surroundings of the horizontal direction of a workpiece | work. By providing the fins or partition plates, the coolant can be made to flow uniformly over the surface of each workpiece. It is also preferable to provide both fins and partition plates.

  Bubbles may be generated when the heated frame or workpiece touches the coolant. Projections projecting from the side surfaces of the workpiece are formed, and if bubbles remain in the projecting portions, the cooling performance decreases and the amount of distortion increases. Therefore, it is preferable that the partition plate includes a rectifying plate that guides the flow of the coolant toward the direction away from the workpiece when the frame body is immersed in the cooling tank. For example, the current plate is provided at a position facing the workpiece side surface, and may be an uneven surface corresponding to the unevenness of the workpiece side surface. Alternatively, the rectifying plate may be a plate that approaches the workpiece side surface from the bottom to the top. In the latter case, the current plate directs the flow of the coolant flowing from the lower side to the upper side of the workpiece toward the side surface of the workpiece. The coolant that collides with the side surface of the work forms a flow from the center of the work toward the outside in the horizontal direction by the reaction. As a result, bubbles on the side surface of the workpiece can be kept away from the workpiece. The baffle plate prevents air bubbles from staying on the workpiece.

  The present invention can also be embodied in a quenching method in which a frame body supporting a plurality of workpieces is moved from a heating furnace and immersed in a cooling tank filled with a cooling liquid. Prior to immersing the work piece into the cooling tank together with the frame body, the method uses a grid-like member with a uniform heat capacity in the surface projection area of the work liquid supported by the frame body. It is characterized by immersing the heated member. As described above, the lattice-like member may be attached to the bottom of the frame.

  ADVANTAGE OF THE INVENTION According to this invention, the hardening apparatus which reduces the dispersion | variation in the distortion amount of the workpiece | work at the time of cooling can be implement | achieved although it is low cost.

A quenching apparatus according to the present invention will be described with reference to the drawings. In FIG. 1, the typical side view of the hardening apparatus 10 is shown. FIG. 2 is a sectional view taken along the line II-II in FIG. In FIG. 2, the work W is indicated by a broken line to help understanding.
The quenching apparatus 10 can quench a plurality of workpieces W at the same time. The workpiece W in the present embodiment is a shaft used for a drive train of an automobile. The quenching apparatus 10 includes a frame body 12 that supports a plurality of workpieces W, a moving device 14 that suspends and moves the frame body 12, a cooling tank 16, and a heating furnace (not shown). The quenching apparatus 10 puts the workpiece W together with the frame body 12 in a heating furnace and heats it, then immerses the workpiece W together with the frame body 12 in the cooling bath 16 for quenching. The moving device 14 moves the frame body 12 from the heating furnace and lowers it to the cooling tank 16. Since the moving device 14 may be a mechanism such as a crane, for example, detailed description is omitted.

  The frame 12 has a substantially cubic outer shape. In the frame body 12, component support bars 22 extending in the horizontal direction are arranged in two stages. In each stage, three component support bars 22 are arranged in parallel. A plurality of workpieces W are suspended on each component support bar 22. That is, a total of nine workpieces W are suspended in each stage, three in each of the vertical and horizontal directions. The frame body 12 includes a partition plate 24 that surrounds each workpiece W in the horizontal direction. Details of the partition plate 24 will be described later. As will be described later, the partition plate 24 has a cylindrical shape surrounding each workpiece W. However, in FIG. 1, the partition plate 24 is depicted as a flat plate in a simplified manner.

The frame body 12 further includes a bottom portion 20. The bottom 20 has a lattice shape in which stainless steel having a thickness of about 40 mm is combined in a lattice shape. The lattice 21 faces in the vertical direction.
The bottom portion 20 covers the entire lower surface of the frame body 12. That is, the bottom portion 20 extends over the entire downward projection area of the plurality of workpieces W that are supported. As shown in FIG. 2, the lattice of the bottom portion 20 is configured such that the lattice 21 is positioned below the workpiece W.

  The bottom portion 20 has substantially the same heat capacity as the total heat capacity of the nine workpieces W. As described above, since the frame body 12 supports and supports nine workpieces W in the horizontal direction, the heat capacity of the bottom portion 20 is the total of the nine workpieces W distributed and supported in the horizontal direction of the frame body 12. Approximately equal to heat capacity. Since the bottom portion 20 is formed in a uniform lattice shape, the heat capacity of the bottom portion 20 is uniform over the entire lower projection area of the workpiece W. Note that when the bottom 20 is viewed microscopically, the heat capacity of the lattice portion 21 of the bottom 20 and the plate of the lattice are naturally different, but when the bottom 20 is viewed macroscopically, the heat capacity of the bottom 20 is It is uniform over the entire work lower area.

The operation and advantages of the quenching apparatus 10 will be described. As described above, the quenching apparatus 10 puts the plurality of workpieces W together with the frame body 12 into a heating furnace and heats them, and then lowers the workpiece W together with the frame body 12 to the cooling tank 16 to cool it.
The workpiece W is heated to about 800 ° C. in a heating furnace filled with a gas containing nitrogen and ammonia. Nitrogen penetrates into the surface layer of the workpiece W in the heating furnace. Next, the quenching apparatus 10 immerses the plurality of workpieces W heated together with the frame body 12 into the cooling tank 16 filled with the cooling liquid Q. This quenching is called N quench or nitriding quenching.

  When the heated frame body 12 is immersed in the cooling tank 16, the bottom portion 20 of the frame body 12 comes into contact with the coolant Q prior to the work W. The coolant Q is a temperature-controlled oil. When the frame body 12 heated to about 800 ° C. contacts the cooling liquid Q at room temperature, the cooling liquid Q is rapidly heated and starts to be disturbed. When the frame 12 is further lowered, the heated coolant Q rises above the bottom 20 through the lattice 21 of the bottom 20. Since the bottom 20 has the lattices 21, the disturbance of the coolant Q spreads uniformly above the bottom 20. Therefore, before the workpiece W comes into contact with the cooling liquid Q, the disturbance of the cooling liquid Q passes through a transition period at the initial stage of the occurrence and becomes almost steady. Since the bottom portion 20 extends to the lower projection area of the plurality of workpieces W, the disturbance of the cooling liquid Q is almost steady over the entire surface area of the cooling liquid Q with which the workpieces W are in contact. When the lower workpiece W comes into contact with the coolant Q, the initial transition period has already passed, so the state of the coolant Q from when the workpiece W starts to come into contact with the coolant Q until the entire frame 12 sinks. Is almost constant. For this reason, before the workpiece | work W contacts the cooling fluid Q, it is suppressed that the local dispersion | variation in a cooling process arises, and the dispersion | variation in the local distortion amount of the workpiece | work W is suppressed.

  When the frame 12 is lowered, the coolant Q to which the lowermost workpiece W is lowered is heated by the bottom portion 20. Since the work W in the lowermost stage touches the cooling liquid Q after the disturbance is stabilized even in the lower layer of the cooling liquid Q, the amount of distortion does not increase compared to the work in the other stages.

  Since the heat capacity of the bottom portion 20 is substantially equal to the total heat capacity of the nine workpieces W distributed and supported in the horizontal direction of the frame 12, the lower portion W touches the coolant Q after the bottom portion 20 touches the coolant Q. In the meantime, the coolant Q is sufficiently disturbed and the temperature of the coolant Q does not rise too much. Further, since the heat capacities are substantially equal, the state when the lower work W comes into contact with the coolant Q following the bottom 20 and the state when the upper work W comes into contact with the coolant Q following the lower work W are equalized. can do. The variation in the distortion amount of the lower workpiece W and the variation in the distortion amount of the upper workpiece W can be made comparable. Since the variation of the strain amount can be made substantially the same across the plurality of workpieces W arranged in the vertical direction, the dimensional variation of the workpiece after quenching can be made uniform.

  Next, the partition plate 24 will be described. FIG. 3 shows an enlarged view around the workpiece W supported by the frame body 12. FIG. 4 shows a cross-sectional view of the partition plate 24. FIG. 4A is a cross-sectional view taken along line IV-IV in FIG. FIG. 4B is a longitudinal sectional view taken along line BB in FIG. FIG. 4C is a longitudinal sectional view taken along the line CC in FIG.

As shown in FIG. 3, the partition plate 24 has a cylindrical shape surrounding the periphery of each workpiece W in the horizontal direction. Although not shown, the cylindrical partition plate 24 is fixed to the frame body 12.
Fins 26 a, 26 b, 26 c, and 26 d that rotate the coolant Q along the side surfaces of the workpiece W are provided below the partition plate 24, that is, below the supported workpiece W. The arrows shown in FIGS. 4B and 4C indicate the flow of the coolant Q. As shown in FIG. 4, the fins 26 a to 26 d are attached in such a direction that the coolant Q turns clockwise when viewed from above.
When the frame body 12 is submerged in the cooling liquid Q by the cylindrical partition plate 24 and the fins 26a to 26d surrounding the work W, the cooling liquid Q moves upward from below the work W while turning around the work W. To flow. Since the coolant Q uniformly touches the periphery of the workpiece W, unevenly distributed distortion hardly occurs in the workpiece W.

  The partition plate 24 and the fins 26a to 26d surrounding the workpiece W are particularly effective when a long cylindrical workpiece (typically a shaft) is supported on the frame body 12 with its longitudinal direction up and down. . This is because the workpiece cooling process using the cooling liquid Q can be made uniform over the longitudinal direction of the workpiece.

  With reference to FIG.5 and FIG.6, the modification of a partition plate is demonstrated. FIG. 5 is a longitudinal sectional view of the partition plate 124. The workpiece W has a step Wa in which the outer shape changes. The step Wa protrudes toward the outside of the workpiece. When the work W is submerged in the coolant Q, bubbles are generated from the disturbed coolant Q. Bubbles tend to stay in the step Wa. Therefore, the partition plate 124 shown in FIG. 5 has a current plate 124a. The rectifying plate 124a is provided at a position corresponding to the step Wa on the surface of the work W, and as shown by an arrow in FIG. 5, the coolant Q flows from the center of the work W toward the outside in the horizontal direction (that is, , A flow toward the direction away from the workpiece). Air bubbles staying on the step Wa of the workpiece W can be released upward by the rectifying plate 124a.

  A partition plate having a shape different from that of the partition plate 124 shown in FIG. 5 will be described with reference to FIG. The partition plate 224 shown in FIG. 6 includes a rectifying plate 224a that protrudes from the inner peripheral surface of the cylindrical partition plate 224 toward the center. The arrows in FIG. 6 indicate the flow of the coolant Q generated by the rectifying plate 224a. As shown in FIG. 6, the rectifying plate 224 a induces the flow of the coolant Q toward the work W below the step Wa of the work W. After the coolant Q approaches the workpiece W, it forms a flow that moves away from the workpiece W by the reaction. The rectifying plate 224a can also cause the flow of the coolant Q in the direction away from the workpiece W, similarly to the rectifying plate 124a of FIG.

  In the quenching apparatus 10 of the above-described embodiment, the bottom portion 20 of the frame body 12 suppresses variations in the distortion amount of the workpiece W. The above effect can be obtained even if a member separate from the frame body 12 is used instead of the bottom portion 20. The quenching method that can suppress the variation in the amount of distortion of the workpiece is the projection of the workpiece, which is the surface area of the coolant and supported by the frame, before the workpiece is immersed in the cooling tank together with the frame. This can be realized by immersing a lattice-shaped member having a uniform heat capacity in the region.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
For example, the bottom of the frame may be formed by arranging members (so-called dummy) having the same shape and heat capacity as the workpiece in the same arrangement as the arrangement of the workpieces in each stage. Since the dummy is arranged in a lattice shape equivalent to the workpiece, such a bottom portion is a modification of the lattice-like bottom portion shown in the embodiment.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

The typical side view of a hardening apparatus is shown. The cross-sectional view of a frame bottom is shown. A partition plate surrounding the work is shown. Sectional drawing of a partition plate is shown. The modification of a partition plate is shown. The other modification of a partition plate is shown.

Explanation of symbols

10: quenching device 12: frame 14: moving device 16: cooling tank 20: bottom 21: lattice 22: component support rods 24, 124, 224: partition plates 26a, 26b, 26c, 26d: fins 124a, 224a: rectification Plate W: Workpiece Q: Coolant

Claims (6)

It is a quenching device that moves a frame body supporting a plurality of workpieces from a heating furnace and immerses it in a cooling tank filled with a coolant,
A quenching apparatus, characterized in that the frame has a grid-shaped bottom portion in which the grid faces in the vertical direction and the heat capacity is uniform in the downward projection area of the workpiece being supported.   The quenching apparatus according to claim 1, wherein a heat capacity of the bottom portion is substantially equal to a total heat capacity of a plurality of works dispersedly supported in the horizontal direction of the frame.   The quenching apparatus according to claim 1 or 2, wherein the frame includes fins for turning the coolant flowing from the lower side to the upper side of the work around the work when immersed in the cooling tank.   The quenching apparatus according to any one of claims 1 to 3, wherein the frame includes a partition plate surrounding the periphery of the workpiece in the horizontal direction.   The quenching apparatus according to claim 4, wherein the partition plate includes a rectifying plate that guides a flow of the coolant toward the direction away from the work when immersed in the cooling bath. It is a quenching method in which a frame supporting a plurality of workpieces is moved from a heating furnace and immersed in a cooling tank filled with a coolant,
Prior to immersing the work together with the frame body into the cooling tank, it is a lattice-shaped member having a uniform heat capacity and heated in the surface area of the cooling liquid and in the downward projection area of the work supported by the frame body. A quenching method characterized by immersing an open member.

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