Heat treatment system

Abstract

To grasp a load applied to an object to be treated during heat treatment.SOLUTION: The heat treatment system 1 includes a heat treatment device 20 for applying heat treatment to an object 10, and a load measuring device 30 for measuring a load applied to the object during the heat treatment by the heat treatment device. The object may be rod-shaped and disposed vertically, and four of the load sensors may be disposed at substantially equal intervals along a circumferential direction of the object. The heat treatment system may further include a moving mechanism configured to move the object and the load sensor relative to the heat treatment apparatus.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a thermal processing system. [Background technology]

[0002] Patent Document 1 describes a method and device for induction hardening a rack bar, in which the entire peripheral surface of the rack bar, including the tooth surface and back surface, and the outer peripheral surface of a shaft portion having a circular cross section that is continuous with the entire peripheral surface, including the tooth surface and back surface, are induction hardened continuously by a moving hardening method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-315851 Summary of the Invention [Problem to be solved by the invention]

[0004] During heat treatment such as induction hardening, a load is applied to the object to be treated. An object of the present invention is to understand the load applied to the object to be treated during heat treatment. [Means for solving the problem]

[0005] In order to achieve the above object, a heat treatment system according to the present invention includes a heat treatment device that performs heat treatment on an object, and a load measuring device that measures a load applied to the object during heat treatment by the heat treatment device. [Effects of the Invention]

[0006] According to the present invention, it is possible to grasp the load applied to an object to be treated during heat treatment. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a thermal processing system. [Figure 2]FIG. 1 is a side view of a thermal processing system. [Figure 3] FIG. 2 is another perspective view of the thermal processing system. [Figure 4] FIG. [Figure 5] FIG. 2 is another perspective view of the load measuring device. [Figure 6] FIG. 2 is a plan view of the load measuring device. [Figure 7] 10 is a graph showing the results of load measurement. [Figure 8] FIG. 2 is an explanatory diagram showing a rack portion of a rack bar. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below.

[0009] Please refer to Figures 1 to 3. The induction hardening system 1 includes an induction hardening device 20 that performs induction hardening on a rack bar 10, which is an object, and a load measuring device 30 that measures the load applied to the rack bar 10 (Figures 2 and 3). The induction hardening system 1 further includes holding jigs 41 and 42 that hold the rack bar 10 in an upright position (Figure 1). The holding jig 41 is located below the holding jig 42.

[0010] The rack bar 10 is a component of an automobile steering system. The rack bar 10 is generally cylindrical and arranged vertically, and has a rack portion 15 with a generally semicircular cross section and a shaft portion 16 that extends axially from the rack portion and also has a generally circular cross section. The rack portion 15 has a tooth surface 15a on which a plurality of teeth are formed, and a back surface 15b that is circumferentially continuous with the tooth surface.

[0011] The induction hardening device 20 includes a heating coil 21 and a coolant spray device 22. The heating coil 21 is arranged so that its axial direction is vertical and so as to surround the rack bar 10. The heating coil 21 is also connected to a high-frequency power supply (not shown). The coolant spray device 22 is ring-shaped, has coolant spray holes formed on its inner periphery, and is arranged so as to surround the rack bar 10. The coolant spray device 22 is located below the heating coil 21.

[0012] The lower end of the rack bar 10 is placed on the holding jig 41, and the upper end of the rack bar 10 is pressed by the holding jig 42, so that the rack bar 10 is held in an upright position. The holding jigs 41 and 42 are controlled by a control device (not shown) of the induction hardening system 1 and move up and down in unison. The movement of the holding jigs 41 and 42 causes the rack bar 10 to move up and down, allowing it to pass through the hollow portion of the heating coil 21 and the hollow portion of the ring-shaped coolant spray device 22.

[0013] When high frequency power is supplied to the heating coil 21 from the above-mentioned high frequency power supply, the outer periphery of the rack bar 10 that is close to the heating coil 21 is induction heated. Next, the rack bar 10 is moved relative to the heating coil 21 and the coolant spraying device 22 so that the outer periphery of the rack bar 10 that has been induction heated by the heating coil 21 comes close to the coolant spraying device 22. Thereafter, coolant is sprayed from the coolant spraying device 22 toward the rack bar 10, thereby cooling the rack bar 10.

[0014] The induction hardening is performed on the rack portion 15 and the shaft portion 16 of the rack bar 10 by repeating heating by the heating coil 21, relative movement of the rack bar 10, and injection of coolant from the coolant injection device 22. At least two of the steps of heating by the heating coil 21, relative movement of the rack bar 10, and injection of coolant may be performed simultaneously.

[0015] As shown in FIGS. 3 to 6, the load measuring device 30 includes a first load cell 31, a second load cell 32, a third load cell 33, and a fourth load cell 34. All four load cells are compression type. The first load cell 31 and the second load cell 32 face each other with the shaft portion 16 in between. The third load cell 33 and the fourth load cell 34 are located below the first load cell 31 and the second load cell 32, and face each other with the shaft portion 16 in between.

[0016] The load button 31a of the first load cell 31, the load button 34a of the fourth load cell 34, the load button 32a of the second load cell 32, and the load button 33a of the third load cell 33 are all in contact with the outer circumferential surface of the shaft portion 16. When viewed in the axial direction of the shaft portion 16, the load button 31a, the load button 34a, the load button 32a, and the load button 33a are arranged in this order at approximately equal intervals along the circumferential direction of the shaft portion 16. When viewed in the axial direction of the rack bar 10, the tooth surface 15a faces the load button 33a.

[0017] The first load cell 31 is supported by a first support portion 35 on the surface opposite to the surface on which the load button is provided. The second load cell 32 is supported by a second support portion 36 on the surface opposite to the surface on which the load button is provided. The distance between the first support portion 35 and the second support portion 36 is adjustable. By adjusting the distance between the two support portions and fixing the two support portions before starting induction hardening, the initial measurement values ​​of the first load cell 31 and the second load cell 32 (load measurement values ​​before starting induction hardening) can be adjusted.

[0018] Specifically, the first support part 35 is supported by a first hand 35H provided to protrude from the hand opening / closing mechanism 50, and the second support part 36 is supported by a second hand 36H provided to protrude from the hand opening / closing mechanism 50. The opposing direction of the first hand 35H and the second hand 36H is parallel to the opposing direction of the first support part 35 and the second support part 36. The first hand 35H and the second hand 36H are biased by the hand opening / closing mechanism 50 in a direction that narrows the distance between the two hands.

[0019] A first adjusting screw 61 is attached to the first hand 35H parallel to the opposing direction of the first support part 35 and the second support part 36, and a second adjusting screw 62 is attached to the second hand 36H parallel to the opposing direction. The head of the first adjusting screw 61 and the head of the second adjusting screw 62 are in contact. When both adjusting screws 61 and 62 are adjusted in the screw-in direction, the gap between the first hand 35H and the second hand 36H narrows, and the first load cell 31 and the second load cell 32 move toward the rack bar 10, increasing the initial loads of both load cells. When both adjusting screws 61 and 62 are turned in the loosening direction, the gap between the first hand 35H and the second hand 36H widens, and the first load cell 31 and the second load cell 32 move away from the rack bar 10, decreasing the initial loads of both load cells.

[0020] The third load cell 33 is supported by a third support portion 37 on the surface opposite to the surface on which the load button is provided. The fourth load cell 34 is supported by a fourth support portion 38 on the surface opposite to the surface on which the load button is provided. The distance between the third support portion 37 and the fourth support portion 38 is adjustable. By adjusting the distance between the two support portions and fixing them before starting induction hardening, the initial measurement values ​​of the third load cell 33 and the fourth load cell 34 can be adjusted.

[0021] Specifically, an outer support portion 37a is provided on the outside of the third support portion 37, and an outer support portion 38a is provided on the outside of the fourth support portion 38. The outer support portions 37a and 38a are fixed by two bolts 37w that are parallel to the opposing directions of the two support portions.

[0022] Four bolts 37r and two bolts 37y are attached to the outer support portion 37a, penetrating the outer support portion 37a along the opposing direction of the outer support portions 37a and 38a. The four bolts 37r have their tips in contact with the third support portion 37 and serve to push the third support portion 37 toward the rack bar 10. The two bolts 37y have their tips fastened to the third support portion 37 and serve to pull the third support portion 37 away from the rack bar 10. When the bolts 37r push the third support portion 37, the third load cell 33 moves toward the rack bar 10, increasing the initial load of the third load cell 33. When the bolts 37y pull the third support portion 37, the third load cell 33 moves away from the rack bar 10, decreasing the initial load of the third load cell 33.

[0023] Similarly, four bolts 38r and two bolts 38y are attached to the outer support part 38a, passing through the outer support part 38a along the opposing direction of the outer supports 37a and 38a. These bolts can be used to increase or decrease the initial load of the fourth load cell 34.

[0024] The load measuring device 30 is configured so that the relative positional relationship between the load measuring device 30 and the rack bar 10 does not change. When induction hardening is performed with the induction hardening device 20 fixed, the rack bar 10 is moved in the axial direction, and the load measuring device 30 also moves following the rack bar 10.

[0025] 7 shows an example of the measurement results of the load cells. The horizontal axis represents time (unit: seconds), and the vertical axis represents the strain load measured by the load cells (unit: kilograms). Broken lines L1 to L4 represent the measurement results of the first load cell 31 to the fourth load cell 34, respectively.

[0026] Period D H indicates the heating period by the heating coil 21, and period D C indicates the coolant injection period. The rack bar 10 is the first period D S1 It stops in the next moving period D M In the following period DS2 The coolant injection period D C At the end of the process, the rack bar is cooled to about 40°C.

[0027] During the heating period, the part to be heated expands, and during the coolant injection period, the part to be cooled contracts.

[0028] As described above, the first load cell 31 and the second load cell 32 face each other across the shaft 16. Ideally, the broken line L1 and the broken line L2 would be symmetrical with respect to a line parallel to the horizontal axis. However, because the measurement result of the first load cell 31 contains noise, the broken line L1 and the broken line L2 are asymmetrical.

[0029] As described above, the third load cell 33 and the fourth load cell 34 face each other across the shaft 16. Therefore, ideally, the broken line L3 and the broken line L4 are symmetrical with respect to a certain straight line parallel to the horizontal axis. In fact, in Figure 7, the broken line L3 and the broken line L4 are also roughly symmetrical with respect to a certain straight line parallel to the horizontal axis.

[0030] FIG. 8 shows the rack portion 15 when the rack bar 10 is viewed from below. In the figure, "12" indicates the 12 o'clock position when the rack portion 15 is likened to an analog clock. Similarly, "3," "6," and "9" in the figure indicate the 3 o'clock position, the 6 o'clock position, and the 9 o'clock position, respectively. The third load cell 33 is located at the 12 o'clock position, the second load cell 32 is located at the 3 o'clock position, the fourth load cell 34 is located at the 6 o'clock position, and the first load cell 31 is located at the 9 o'clock position. The tooth surface 15a faces the 12 o'clock direction.

[0031] For the shaft 16 of the rack bar 10, the same object of measurement as in Figure 7, the error (runout) from a perfect circle was measured using a dial gauge, in addition to the load measurement using a load cell. The maximum runout before induction hardening was 0.11 mm in the 11 o'clock direction, and the maximum runout after induction hardening was 0.87 mm in the 7 o'clock direction. This means that the rack bar 10 was deformed by approximately 0.98 mm (= 0.11 mm + 0.87 mm) in the 7 o'clock direction due to hardening distortion. Generally speaking, it can be said that the rack bar 10 was deflected toward the tooth surface 15a before induction hardening, but deflected toward the back surface 15b after induction hardening.

[0032] Referring again to FIG. 7, as shown by reference characters Y3 and Y4, the moving period D M At the end of this period, the load on the third load cell 33 decreases, and the load on the fourth load cell 34 increases. The decrease in the load on the third load cell 33 means that the workpiece (rack bar 10) has moved away from that load cell. The increase in the load on the fourth load cell 34 means that the workpiece has been pressed against that load cell.

[0033] Since the value of the second load cell 32 remains almost unchanged, it is considered that there is almost no change in the 3 o'clock and 9 o'clock directions (as mentioned above, the measurement result of the first load cell 31 contains noise).

[0034] As such, the measurement results shown in Figure 7 indicate that a load was applied to the workpiece in approximately the 6 o'clock direction (from the tooth surface 15a toward the top of the back surface 15b). On the other hand, as mentioned above, measurement of the workpiece with a dial gauge revealed that the deformation direction was approximately the 7 o'clock direction. The deformation direction determined by the dial gauge and the load direction determined by the load cell are roughly the same. Since the direction of the load applied to the rack bar during heat treatment (Figure 7) and the distortion direction of the workpiece after heat treatment (the 7 o'clock direction in Figure 8) roughly coincide with each other, it is believed that distortion occurred in the load direction.

[0035] According to the embodiments described so far, it is possible to measure the magnitude and direction of the load applied to the workpiece due to deformation of the workpiece that occurs during induction hardening. The relationship between the magnitude and direction of the load applied to the workpiece and the deformation of the workpiece can be quantified. Furthermore, the measurement results obtained by the above embodiments can also serve as an indicator for determining the direction and magnitude of external force that should be applied to the workpiece during induction hardening to effectively suppress deformation. In other words, this leads to a deformation correction mechanism that corrects deformation during induction hardening.

[0036] Conventionally, the amount of deformation after heat treatment (such as the amount of deformation or runout of the product dimensions) is measured outside the heat treatment device, and the behavior during heat treatment is inferred from the measurement results before and after the heat treatment. However, according to the above-described embodiment, it is possible to measure the change in load over time during heat treatment.

[0037] The four load cells are arranged at approximately equal intervals around the periphery of the rack bar, making it possible to measure strain in any direction. Furthermore, even if the object is moved, the measurement position of the load cells does not change, which increases the reliability of the measurement results compared to when the measurement position changes over time.

[0038] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical concept of the present invention. [Explanation of symbols]

[0039] 1. Induction hardening system 10 Rack Bar 15 Rack section 15a Tooth surface 15b Back 16 Shaft 20 High-frequency hardening equipment 21 Heating coil 22 Coolant injection device 30 Load measuring device 31~34 Load cells 35~38 Support part

Claims

1. a heat treatment device for performing heat treatment on an object; a load measuring device that measures a load applied to the object during heat treatment by the heat treatment device; A heat treatment system comprising:

2. The object is rod-shaped and arranged vertically; The four load sensors are arranged at approximately equal intervals along the circumferential direction of the object. The thermal processing system of claim 1 .

3. The heat treatment system according to claim 1 , further comprising a movement mechanism that moves the object and the load sensor relative to the heat treatment device.

4. The heat treatment system according to claim 1 , further comprising an adjustment mechanism that adjusts a position of the load sensor relative to the object before the heat treatment by the heat treatment apparatus starts.

5. 3. The heat treatment system according to claim 1, wherein the heat treatment device is a high frequency induction heating device and a coolant injection device.

6. 3. The heat treatment system according to claim 1, wherein the load sensor is a compression type load cell.

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