JP5446002B2 - Induction hardening equipment - Google Patents

Description

  The present invention relates to an induction hardening apparatus that quenches a ring-shaped groove provided on the inner surface of a cylindrical workpiece by high-frequency heating and cooling with a cooling liquid.

  2. Description of the Related Art Conventionally, some cylindrical workpieces used in a steering system of an automobile are provided with an annular groove in which a large number of balls are fitted on the inner surface, such as a hub bearing, and the annular groove is quenched. In such a cylindrical workpiece, the annular groove is heat-treated while preventing the portions other than the annular groove from being heated.

  For example, in the heating device shown in FIG. 3 of Patent Document 1, when heating a cylindrical workpiece, a concentrating ring that also serves as a cradle is provided in the notch portions (notch holes) at the upper and lower ends of the inner surface of the cylindrical workpiece. The inner surface of the U groove, which is an annular groove, was heated by passing a high-frequency current through the heating conductor.

  In the heating apparatus shown in FIG. 1 of Patent Document 1, a cylindrical workpiece is placed on a pedestal and positioned, and a pair of concentrator rings supported by a screw shaft are arranged on both ends in the axial direction of the heating conductor. The inner surface of the U groove, which is an annular groove, was heated through a high frequency current.

  In such a heating device, when heating is performed without using a concentrating ring, the magnetic flux generated from the heating conductor spreads to both ends in the axial direction of the cylindrical workpiece, and as a result, the heating range is a notch whose stepped portion is a stepped portion. Reach the boundary with the department. In particular, the edge is excessively heated by the so-called edge effect. If it becomes so, a hardness difference will arise in the boundary part where stress concentrates, and it will become easy to produce a crack by stress concentration in this part.

  However, if a concentrator ring is used, it is possible to prevent the magnetic flux from spreading to both ends of the heating conductor, so that the heating range does not reach the boundary with the notch. It is possible to prevent a difference in hardness from occurring at the boundary portion and to prevent cracks caused by stress concentration at the boundary portion.

JP-A-8-176651

  However, the technique described in Patent Document 1 heats an annular groove of a cylindrical workpiece at high frequency, and in order to quench the cylindrical workpiece, it is necessary to cool the cylindrical workpiece with a coolant. It is impossible to complete the induction heating and quenching. For this reason, when quenching a plurality of cylindrical workpieces, it is difficult to stabilize various conditions such as the cooling rate, and the quality in the annular groove of the cylindrical workpiece is likely to vary.

  In addition, since the cylindrical workpiece is placed on the cradle and positioned at a predetermined position for high-frequency heating, if there is foreign matter on the surface of the cradle of the cylindrical workpiece, the tubular workpiece, the heating conductor and the concentrator The relative position of the product is displaced, and only a desired range cannot be quenched with high accuracy, and the quality of the product obtained may vary.

  The present invention has been devised in view of the above-described problems, and induction hardening can be performed with high accuracy and uniform quenching of an annular groove provided on the inner surface of a cylindrical workpiece with a single device. An object is to provide an apparatus.

  In order to achieve the above object, the present invention is an induction hardening apparatus for quenching an annular groove of a cylindrical workpiece having an annular groove on the inner surface thereof, and a column whose upper portion is erected so as to be inserted into the cylindrical workpiece. And positioned on the outer periphery of the column, having an annular recess on the upper inner edge, and housing and placing the lower end of the cylindrical workpiece in the annular recess so that the cylindrical workpiece is concentric with the column and has a predetermined height. A lower jig to be supported by the base, a high-frequency heating coil provided on the support so as to face the annular groove of the cylindrical work supported by the lower jig, and an inner surface of the cylindrical work supported by the lower jig Positioned on the outer peripheral surface of the support so that it faces the inner surface below the annular groove of the cylindrical workpiece supported by the lower jig and the plurality of injection holes opened in the outer peripheral surface of the support so as to inject the coolant A shield ring made of a material that is mounted and has higher conductivity than the cylindrical workpiece Provided, the cooling liquid is provided can flow gap between the lower jig and the shield ring.

  According to the above configuration, the high-frequency heating coil and the coolant injection hole are provided at a predetermined position of the support column, and the lower jig that supports the cylindrical workpiece at a predetermined height concentrically with the support column Since a shield ring that is disposed at a predetermined position of the cylindrical workpiece and is opposed to the inner surface below the annular groove of the cylindrical workpiece supported by the lower jig is mounted at a predetermined position on the outer peripheral surface of the support column, If the cylindrical workpiece is supported and heated by the high frequency heating coil, the annular groove can be heated while accurately preventing the lower side of the cylindrical workpiece from being heated beyond the predetermined range by the shield ring. Thus, the heated annular groove can be cooled by injecting the coolant from the injection hole. Therefore, it is possible to quench the annular groove provided on the inner surface of the cylindrical workpiece with a single device.

  At that time, since the lower jig and the shield ring can be positioned separately, the shield ring can be arranged at an appropriate position with respect to the cylindrical workpiece supported by the lower jig, and the annular groove can be heated with high accuracy. .

  In addition, since a gap through which the coolant can flow is provided between the lower jig and the shield ring, foreign matter can be prevented from being deposited and deposited in the annular recess of the lower jig, and a large number of cylindrical workpieces can be formed. It can be supported on the lower jig with good repeatability.

  Furthermore, since it can be cooled by the cooling liquid ejected from the injection hole without moving the cylindrical workpiece after heating, even if a large number of cylindrical workpieces are repeatedly cooled, they can be cooled under the same conditions each time. The annular groove of the cylindrical workpiece can be uniformly quenched.

  In the induction hardening apparatus of the present invention, the gap between the lower jig and the shield ring is formed so that the coolant injected from the injection hole is retained between the cylindrical workpiece and the support column and can flow down. Is preferable.

  If it does in this way, the cooling fluid injected from each injection hole after heating will not only contact and cool only the corresponding position of a cylindrical workpiece, but also contacts the wide range of the inner surface of a cylindrical workpiece. It is possible to cool the whole uniformly. Therefore, it is possible to quench the annular groove more uniformly.

  According to the present invention, the lower jig that is positioned and arranged around the outer periphery of the support and supports the cylindrical work concentrically and at a predetermined height, and the annular groove of the cylindrical work supported by the lower jig. A high-frequency heating coil provided so as to face each other, a plurality of injection holes for injecting coolant into the annular groove of the cylindrical workpiece supported by the lower jig, and the annular groove of the cylindrical workpiece supported by the lower jig It is arranged so as to face the lower inner surface, and includes a shield ring made of a material having higher conductivity than the cylindrical workpiece, and a gap through which coolant can flow is provided between the lower jig and the shield ring. Therefore, it is possible to provide an induction hardening apparatus capable of performing a quenching process with high positional accuracy and uniformity on the annular groove provided on the inner surface of the cylindrical workpiece with a single apparatus.

It is a longitudinal cross-sectional view which shows the principal part of the induction hardening apparatus which concerns on 1st Embodiment by this invention. It is a disassembled perspective view which shows the principal part of the induction hardening apparatus shown in FIG. It is sectional drawing which shows the cylindrical workpiece of the process target of the induction hardening apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the principal part of the induction hardening apparatus which concerns on 2nd Embodiment. It is a disassembled perspective view which shows the principal part of the induction hardening apparatus of FIG.

Hereinafter, an induction hardening apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
First, the cylindrical workpiece which is a processing target of the induction hardening apparatus according to the embodiment is made of a steel material having an annular groove on the inner surface. This embodiment is an example applied to an outer ring W of a hub bearing used in a steering system of an automobile as shown in FIG.

  The outer ring W of the hub bearing has two rows of annular grooves (race surfaces) a and b, and has a plurality of mounting flanges c on the outer peripheral side on one end side. Notches d and e are provided on both sides of b. In the outer ring W of this hub bearing, the notched portion d on the side having the mounting flange c is not subjected to heating and quenching treatment, so that the two rows of annular grooves a and b and both annular grooves a and b are formed. It is desired that the heating and quenching process be performed on the area in between.

  As shown in FIGS. 1 and 2, the induction hardening apparatus 1 </ b> A according to this embodiment includes a support column 10 in which an upper portion can be inserted into the outer ring W, and an outer circumferential position of the support column 10. A lower jig 11A for supporting the outer ring W concentrically with the support column 10 at a predetermined height by placing the lower end of the outer ring W in the annular recess 11d and placing it on the lower jig 11A. A high frequency heating coil 12 provided on the support column 10 so as to face the annular grooves a and b of the supported outer ring W, and inner surfaces below the annular grooves a and b of the outer ring W supported by the lower jig 11A. A shield ring 13 positioned and mounted on the outer periphery of the support column 10 is provided so as to face each other. Note that the lower jig 11A and the shield ring 13 are formed of separate members, and a predetermined gap S2 is provided between them.

  In this induction hardening apparatus 1 </ b> A, annular first to fourth cores 14, 15, 16, 17 are further provided so as to sandwich each high frequency heating coil 12, and between the support column 10 and the first core 14 and the second one. Spacers 22 and 23 are disposed between the core 15 and the third core 16, respectively, and a cap 20 is disposed on the top. The cap 20 and the spacer 23 are provided with a plurality of injection holes 20a and 23a opened in the outer peripheral surface of the support column 10 so as to inject the coolant into the annular grooves a and b of the outer ring W supported by the lower jig 11A. It has been.

  Next, the configuration of the induction hardening apparatus 1A will be described.

  The column 10 is a hollow cylinder made of an insulating material, and the high-frequency heating coil 12, the first to fourth cores 14, 15, 16, 17 and the spacers 22, 23 are positioned concentrically and fixed at a predetermined height. It is configured to be possible.

  The high-frequency heating coil 12 is disposed at a position corresponding to the annular grooves a and b of the outer ring W, and has two turns of the heating conductors 12a formed in a shape and a diameter corresponding to the annular grooves a and b, and each heating conductor 12a. A lead conductor (not shown) for energizing and circulating the coolant is formed by a single copper tube. For example, a copper pipe is set up as a straight pipe (formation of lead conductor), bent at the top at the outside and then rounded, bent at the inside, bent up at the outside, then turned around and bent inside (two turns) Of the heating conductor 12a in the shape of a straight line), and a shape of falling as a straight pipe (formation of the lead conductor).

  The first to fourth cores 14, 15, 16, and 17 are made of a material having heat resistance, heat insulation, and non-conductivity to closely hold the heating conductor 12 a.

  The spacers 22 and 23 are made of a heat-resistant material and serve to adjust the height of the heating conductor 12a, for example. The spacer 23 has a plurality of injection holes 23a that are radially opened on the outer peripheral surface, and is supplied with quenching liquid from a flow path (not shown) provided in the column 10 for quenching from the injection holes 23a. The coolant is injected between the inner surfaces a and b of the outer ring W.

  The cap 20 is formed of, for example, an insulating heat-resistant resin, and has a plurality of injection holes 20a that are opened in the radial direction on the outer peripheral surface. Is supplied so that the quenching coolant from the injection hole 20a is injected onto the inner surface a of the outer ring W.

  In this apparatus, for example, the first to fourth cores 14, 15, 16, 17, the spacers 22, 23, the heating conductor 12 a and the cap 20 are fixed to the upper part of the support column 10, so that the inner space is sealed. In addition, it may be formed so as to flow into the injection holes 20 a and 23 a by supplying a quenching coolant into the support column 10.

  The lower jig 11A includes an annular plate-like copper or stainless steel base plate 11a that is positioned and placed on the gantry 18, and an annular plate-like ceramic receptacle placed on the inner diameter side portion of the upper surface of the base plate 11a. The support plate 11b includes a stainless steel ring block 11c mounted on the outer diameter side portion of the upper surface of the base plate 11a and fixed by pressing the support plate 11b.

  In the lower jig 11A, the upper surface of the receiving plate and the inner surface of the ring block 11c form an annular recess 11d for supporting the outer ring W. The receiving plate 11b receives the outer ring W, and the ring block By engaging the lower end outer surface of the outer ring W at 11c, the outer ring W can be positioned and supported so as to be concentric with the central axis of the support column 10.

  The gantry 18 and the lower jig 11 </ b> A are configured to be rotatable relative to the column 10 about the central axis of the column 10 by a driving unit (not shown).

  The shield ring 13 is made of a material that has higher conductivity than the outer ring W and blocks magnetic flux, and is, for example, a copper cylinder. The shield ring 13 has a screw hole (not shown), is fitted to the upper portion of the support column 10 before the high-frequency heating coil 12 is attached, and is fastened and fixed with screws screwed into a plurality of screw holes arranged in the circumferential direction. Has been. The shield ring 13 is mounted to be spaced apart and opposed to the lower notch d on the inner surface of the outer ring W placed on the lower jig 11A. Since it is the structure which fastens a screw to the support | pillar 10, height adjustment is possible.

  By attaching such a shield ring 13 to the support column 10 with a precise adjustment of the distance from the high-frequency heating coil 12, the magnetic flux generated from the heating conductor 12a does not spread to the lower notch d. It can be shielded. In this embodiment, the lock ring 19 may be provided on the lower side in order to facilitate fine adjustment of the height of the shield ring 13.

  The outer diameter of the shield ring 13 is set to be, for example, 2 mm smaller than the inner diameter of the base plate 11a of the lower jig 11A, and a gap S2 is formed therebetween. The flow amount of the coolant injected from the injection holes 20a, 23a onto the inner surface of the outer ring W is adjusted by the gap S2. That is, the gap S2 has a circulation amount in which the quenching coolant injected from the injection holes 20a and 23a onto the inner surface of the outer ring W stays in the space corresponding to the inner surface a of the outer ring W and smoothly flows down. Is set to In this embodiment, the interval of the gap S2 is set so that the liquid level of the coolant that has been ejected from the ejection holes 20a and 23a and stays between the annular groove a and the annular groove b.

  Next, the assembly procedure of the induction hardening apparatus 1A will be described.

  An induction hardening apparatus 1A has a cylindrical cylindrical shield ring 13 fitted and fixed to a cylindrical container-like column 10, and two lead conductors of a high-frequency heating coil 12 made of a copper tube are accommodated in the column 10 and the lower end. And the first to fourth cores 14, 15, 16, 17 and the spacers 22, 23 for sealing and supporting and insulating the lower, middle, and upper sides of the two heating conductors 12 a are attached, The cap 20 is arrange | positioned at the top part, and the cap 20, the heating conductor 12a, the 1st-4th cores 14-17, and the spacers 22 and 23 are fixed concentrically. On the other hand, the gantry 18 is installed around the outer periphery of the support column 10, the lower jig 11 </ b> A is positioned and placed on the gantry 18, and the lower jig 11 </ b> A is positioned and placed concentrically with the support column 10.

  At that time, a quenching coolant supply source (not shown) is connected to a flow path provided in the support column 10 so that the coolant can be supplied to the injection holes 20a and 23a on the lower outer surface of the support column 10. A conductor coolant supply source (not shown) is connected to the outer end of the lead conductor continuous with the heating conductor 12a, and a high-frequency power source (not shown) is connected.

  Next, a method for quenching by heating the annular grooves a and b of the outer ring W using the induction hardening apparatus 1A will be described.

  First, the outer ring W is placed on the lower jig 11 </ b> A, and the outer ring W is accurately positioned with respect to the high-frequency heating coil 12 and the shield ring 13. In this state, the two-turn heating conductor 12a corresponds to the inner surfaces a and b of the outer ring W, and the upper end of the shield ring 13 corresponds to the upper end of the notch d on the lower inner surface of the outer ring W.

  When the high frequency power supply is turned on, a high frequency current is passed through the high frequency heating coil 12. The inner surfaces (race surfaces) a and b of the outer ring W are heated to a predetermined quenching temperature by the high-frequency current magnetic flux. Since the magnetic ring of high frequency current does not reach the notch part d below the inner surface of the outer ring W by the function of the shield ring 13, the notch part d is not heated to the quenching temperature.

  Thereafter, the high-frequency current to the high-frequency heating coil 12 is cut off, and immediately after that, a quenching coolant supply source (not shown) is operated. Then, the coolant is injected from the injection holes 20a and 23a, and the inner surface of the outer ring W is rapidly cooled.

  At this time, the gap S2 between the coolants restricts the amount of quenching coolant that has been injected from the injection holes 20a and 23a onto the inner surface of the outer ring W, so that the coolant is in the space corresponding to the inner surface a of the outer ring W. Thus, the inner ring a of the outer ring W is effectively cooled. Therefore, the inner surfaces a and b of the outer ring W are austenitized by high-frequency heating, rapidly cooled to have a martensite structure, and the cross-hatched portion shown in the cross-sectional view of the outer ring W is quenched.

  During cooling, it is also possible to cool by injecting a coolant onto the outer surface of the outer ring W by a cooling means (not shown) provided outside the outer ring W.

  After cooling is completed, supply of the coolant is stopped, the outer ring W is removed from the lower jig 11A, the next outer ring W is fitted and placed in the annular recess 11d of the lower jig 11A, and the above heating is performed again. And the quenching process of the some outer ring | wheel W is performed by repeating and cooling. Here, since there is a gap S2 between the lower jig 11A and the shield ring 13, even if foreign matter such as debris on the surface due to quenching of the inner surfaces a and b of the outer ring W exists on the receiving plate 11b, the gap Since it can discharge | emit from S2, it does not accumulate, but it can heat-process, hold | maintaining the positioning position of the outer ring W correctly each time.

  According to the induction hardening apparatus 1A as described above, the high frequency heating coil 12 and the coolant injection hole 23a are provided at predetermined positions of the support column 10, and the outer ring W is connected to the support column 10 around the outer periphery of the support column 10. A lower jig 11A that is concentrically supported at a predetermined height, and a shield ring 13 that faces the inner surface below the annular grooves a and b of the outer ring W supported by the lower jig 11A are positioned and provided. Therefore, the annular grooves a and b can be heated by heating with the high-frequency heating coil 12 with the outer ring W supported by the lower jig 11A, and the annular ring heated by injecting the coolant from the injection hole 23a. The grooves a and b can be cooled. Therefore, the annular grooves a and b provided on the inner surface of the outer ring W can be quenched by a single device. At that time, since it is not necessary to move the outer ring W after heating or to cool it with another cooling device, a large number of outer rings W can be repeatedly cooled under the same conditions, and the annular grooves a and b can be made uniform. It can be quenched.

  At this time, since the lower jig 11A and the shield ring 13 can be positioned separately, the shield ring 13 can be accurately placed at an appropriate position with respect to the outer ring W supported by the lower jig 11A, and the annular groove a , B can be heated.

  In addition, since the gap S2 through which the coolant can flow is provided between the lower jig 11A and the shield ring 13, even if foreign matter is present in the annular recess 11d of the lower jig 11A, it is easily discharged from the gap S2. It is possible to prevent foreign matter from accumulating in the annular recess 11d. Therefore, it is possible to repeatedly support the plurality of outer rings W with the lower jig with high accuracy.

Furthermore, since the outer ring W can be cooled by the coolant ejected from the injection hole 20a without being moved after the heating, even if the outer ring W is repeatedly cooled, it can be cooled under the same conditions every time. The annular grooves a and b of each outer ring W can be uniformly quenched.
(Second Embodiment)
As shown in FIGS. 4 and 5, the induction hardening apparatus 1 </ b> B according to this embodiment includes a support 10, a lower jig 11 </ b> B, an induction heating coil 12, a shield ring 13, and first to fourth cores 14. 15, 15, 16, 17, spacers 22, 23, a cap 20, and injection holes 20 a, 23 a. The difference from the induction hardening apparatus 1A shown in FIGS. 1 and 2 is the configuration and attachment of the lower jig 11B.

  Hereinafter, differences will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

  The lower jig 11B includes a copper or stainless steel base plate 11a ′ having a boss portion 11e, an annular plate-shaped ceramic receiving plate 11b ′ placed on the inner diameter side portion of the upper surface of the base plate 11a ′, It comprises a stainless steel ring block 11c ′ which is placed on the outer diameter side portion of the upper surface of the base plate 11a ′ and which is fixed by pressing the receiving plate 11b ′.

The lower jig 11B is fixed to the support column 10 side by tightening a screw 26 screwed to the boss portion 11e ′ of the base plate 11a ′ to the outer surface of the shield ring 13. In this embodiment, since the base plate 11a ′ has the boss portion 11e ′, a plurality of gaps S3 through which the coolant flows are provided in the circumferential direction in a non-annular manner. The clearance S3 is also set so that the quenching coolant injected from the injection holes 20a and 23a onto the inner surface of the outer ring W is maintained in a space corresponding to the inner surface a of the outer ring W and flows smoothly. Has been. Thereby, cooling with respect to the inner surfaces a and b of the outer ring W is effectively performed.
(Other embodiments)
The present invention is not limited to the exemplification of the above-described embodiment, and the technical scope of the claims includes various design changes within the scope not departing from the gist of the invention.

  The example of the above embodiment shows a case where the present invention is applied to a hub bearing used in an automobile steering system. However, the present invention has a quenching surface having two rows of annular grooves (race surfaces). It is not limited to being. The above embodiment shows a case where the present invention is applied to a hub bearing used in a steering system of an automobile. Therefore, the mounting flange is on the lower side and the spread of the magnetic flux on the lower side to the notch is shielded. The shield ring that shields the spread of the magnetic flux to the notch on the upper side is not attached. If it is necessary to shield the spread of the magnetic flux to the upper notch, a shield ring may be attached, and the shield ring can also be attached on the upper side with a design change. The present invention includes such modifications.

1A, 1B Induction hardening apparatus 10 Post 11A, 11B Lower jig S2, S3 Gap 12 High frequency heating coil 12a Heating conductor 13 Shield ring 14, 15, 16, 17 First to fourth cores W Outer ring (cylindrical workpiece)
20 Cap 20a Injection hole 22, 23 Spacer 23a Injection hole

Claims (3)

It is an induction hardening apparatus for quenching the annular groove of a cylindrical workpiece having an annular groove on the inner surface,
A column whose upper part is erected so that it can be inserted into the cylindrical workpiece,
Positioned and arranged on the outer periphery of the column, has an annular recess on the upper inner edge, and accommodates and places the lower end of the cylindrical workpiece in the annular recess so that the cylindrical workpiece is concentric with the column. And a lower jig that supports a predetermined height;
A high-frequency heating coil provided on the support so as to face the annular groove of the cylindrical workpiece supported by the lower jig;
A plurality of injection holes opened in the outer peripheral surface of the support so as to inject cooling liquid onto the inner surface of the cylindrical workpiece supported by the lower jig, and the cylindrical workpiece supported by the lower jig. Positioned and mounted on the outer peripheral surface of the column so as to face the inner surface below the annular groove, and a shield ring made of a material having higher conductivity than the cylindrical workpiece,
An induction hardening apparatus in which a gap through which the coolant can flow is provided between the lower jig and the shield ring.   2. The induction hardening apparatus according to claim 1, wherein the gap is formed so that the cooling liquid injected from the injection hole is allowed to flow between the cylindrical workpiece and the support column to flow down.   The induction hardening apparatus according to claim 1 or 2, wherein the cylindrical workpiece is an outer ring of a hub bearing.

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