Polishing method and apparatus

Abstract

To provide a polishing method capable of easily cooling an end face of a coil spring.SOLUTION: A coil spring S is passed between a pair of grinding wheels 3A and 3B a plurality of times to polish an end face SF of the coil spring S by the grinding wheels 3A and 3B, and mist M is sprayed to the end face SF of the coil spring S before or after the coil spring S passes between the grinding wheels 3A and 3B.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polishing method and apparatus for polishing the end face of a coil spring. [Background technology]

[0002] A known conventional polishing method, as described in Patent Document 1, for example, involves passing a coil spring between a pair of rotating grindstones multiple times and polishing each end face of the coil spring with the grindstone.

[0003] In such a polishing method, if the end surface of the coil spring becomes hot due to polishing, the hardness or mechanical properties may change, or the coil shape may be deformed. This tendency becomes particularly pronounced when the grinding allowance is increased or the grinding wheel rotation speed is increased to increase productivity. For this reason, the polishing method of Patent Document 1 cools the end surface of the coil spring during polishing.

[0004] The end faces of the coil spring are cooled by bringing cooling plates into contact with both end faces of the coil spring before and after it passes between the grinding wheels. The cooling plates are cooled by circulating a cooling medium through pipes that run through the inside of the plates, and the end faces of the coil spring are cooled by heat exchange during contact.

[0005] In this polishing method, both end surfaces of the coil spring can be directly cooled by the cooling plates, which efficiently suppresses the temperature rise of the coil spring. As a result, it is possible to increase the grinding allowance and increase the rotation speed of the grinding wheel, thereby improving the productivity of coil springs.

[0006] However, the cooling plate has a complex structure because it circulates a cooling medium. Furthermore, because the cooling plate comes into direct contact with the end face of the coil spring, it is prone to wear and requires maintenance. As a result, conventional polishing methods have not been able to easily cool the end face of the coil spring. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4964826 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved is that the end faces of the coil spring cannot be easily cooled. [Means for solving the problem]

[0009] The present invention provides a polishing method that includes passing a coil spring between a pair of grinding wheels multiple times to polish each end face of the coil spring with the grinding wheels, and spraying a mist onto the coil spring before or after the coil spring passes between the grinding wheels.

[0010] The present invention also provides a polishing device comprising a pair of grinding wheels that polish the end faces of a coil spring that passes through, a holding section that holds the coil spring and passes the coil spring between the pair of grinding wheels multiple times, and a sprayer that sprays mist onto the coil spring before or after the coil spring passes between the grinding wheels. [Effects of the Invention]

[0011] The present invention can easily cool the end surface of the coil spring by mist. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a plan view showing a polishing apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the polishing apparatus of FIG. [Figure 3] FIG. 3 is a flowchart showing a polishing method according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] The purpose of easily cooling the end face of a coil spring has been achieved by a polishing method and device that sprays mist onto the end face of the coil spring.

[0014] In the polishing method, the coil spring S is passed between a pair of grinding wheels 3A and 3B multiple times, and the end surface SF of the coil spring S is polished by the grinding wheels 3A and 3B, respectively. Then, a mist M is sprayed onto the end surface SF of the coil spring S before or after the coil spring S passes between the grinding wheels 3A and 3B.

[0015] Polishing may continue after spraying of the mist M has ended.

[0016] The polishing may include heavy polishing in which the distance between the grinding wheels 3A and 3B is narrowed stepwise, and light polishing in which the distance between the grinding wheels 3A and 3B is fixed after the heavy polishing.

[0017] In this case, the mist M is sprayed during at least a part of the heavy polishing. Preferably, the mist M is sprayed only during the heavy polishing. More preferably, the mist M is sprayed until the heavy polishing is completed.

[0018] In one embodiment, a pair of grinding wheels 3A and 3B may be arranged vertically facing each other, and a support table 13 may be placed adjacent to one of the pair of grinding wheels 3A and 3B, 3A, which is located below the pair of grinding wheels 3A and 3B. In this case, the coil spring S is circulated between the support table 13 and the pair of grinding wheels 3A and 3B, and this circulation causes the coil spring S to pass between the pair of grinding wheels 3A and 3B multiple times. The mist M is sprayed only onto the end face SF located above the coil spring S.

[0019] The polishing device 1 includes a pair of grindstones 3A and 3B, a holder 5, and a sprayer .

[0020] The pair of grinding wheels 3A and 3B each grind an end surface SF of the coil spring S that passes between them. The holding unit 5 holds the coil spring S and passes the coil spring S between the pair of grinding wheels 3A and 3B multiple times. While the holding unit 5 moves the coil spring S, the pair of grinding wheels 3A and 3B grind the coil spring S that passes between them, thereby performing a grinding operation. The sprayer 7 sprays a mist M onto the end surface SF of the coil spring S before or after the coil spring S passes between the grinding wheels 3A and 3B.

[0021] After the spraying of the mist M is completed, the holding unit 5 may continue the operation of passing the coil spring S between the pair of grindstones 3A and 3B.

[0022] The pair of grinding wheels 3A and 3B may be supported so that the gap between them can be changed. In this case, heavy polishing can be performed while gradually narrowing the gap between them, and then light polishing can be performed with the gap between them fixed after the heavy polishing.

[0023] The polishing apparatus 1 may also include a support table 13. In this case, the holder 5 circulates the coil spring S between the support table 13 and the pair of grinding wheels 3A and 3B, and the pair of grinding wheels 3A and 3B polish the coil spring S passing between them, thereby performing the polishing operation. The sprayer 7 only sprays the mist M onto the end face SF located above the coil spring S. [Example]

[0024] [Polishing equipment] FIG. 1 is a plan view showing a polishing apparatus according to a first embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the polishing apparatus of FIG.

[0025] As shown in FIGS. 1 and 2, the polishing device 1 of this embodiment polishes both end surfaces SF of a coil spring S, and includes a pair of grindstones 3A and 3B, a storage table 5, and a sprayer .

[0026] The pair of grinding wheels 3A and 3B face each other above and below, sandwiching a part of the storage table 5. These grinding wheels 3A and 3B are driven relatively to the storage table 5, thereby enabling grinding of the coil spring S held on the storage table 5.

[0027] In this embodiment, the grinding wheels 3A and 3B are, for example, resinoid grinding wheels, and are formed in a disk shape. The grinding wheels 3A and 3B are rotated around their centers by electric motors 9A and 9B, respectively. The electric motors 9A and 9B have output shafts 11 connected to the grinding wheels 3A and 3B, respectively, so that they rotate integrally with the grinding wheels 3A and 3B.

[0028] The material of the grinding wheels 3A and 3B may be appropriately selected depending on the material of the coil spring S. The grinding wheels 3A and 3B may be configured to be driven relatively only by the rotation of the accommodation table 5, without being rotated.

[0029] The grinding wheel 3A located below is arranged adjacent to the support table 13. The support table 13 is supported by a base or the like (not shown) of the polishing apparatus 1, and supports from below the coil spring S accommodated in the accommodation table 5 outside the space between the pair of grinding wheels 3A and 3B.

[0030] The support table 13 in this embodiment is disk-shaped and has a notch 13a on its outer periphery. A portion of the grinding wheel 3A is disposed within the notch 13a. The surface 13b of the support table 13 is generally formed as a flat surface capable of supporting the coil spring S. The surface 3Aa of the grinding wheel 3A is also formed as a flat surface and is disposed so as to be flush with the surface 13b of the support table 13.

[0031] As will be described later, if the coil spring S can circulate between the pair of grinding wheels 3A and 3B and the support table 13, there may be a step between the surface 13b of the support table 13 and the surface 3Aa of the grinding wheel 3A.

[0032] The lower grinding wheel 3A comes into contact with the lower end face SF of the coil spring S that passes sequentially between the grinding wheels 3A and 3B. Outside the lower grinding wheel 3A (outside the gap between the grinding wheels 3A and 3B), the support table 13 comes into contact with the lower end face SF of the coil spring S in response to the rotation of the storage table 5. The upper grinding wheel 3B comes into contact with the upper end face SF of the coil spring S that passes sequentially between the grinding wheels 3A and 3B in response to the rotation of the storage table 5.

[0033] The upper and lower grinding wheels 3A and 3B are configured to be able to rise and fall by an actuator 15 such as a ball screw, thereby supporting the pair of grinding wheels 3A and 3B so that the distance between them can be changed.

[0034] In this embodiment, the pair of grinding wheels 3A and 3B are configured to perform heavy grinding while gradually narrowing the gap between them, and then perform light grinding with the gap fixed after the heavy grinding. The method for gradually narrowing the gap between the pair of grinding wheels 3A and 3B is to repeatedly lower and stop the upper grinding wheels 3A and 3B. However, the gap between the pair of grinding wheels 3A and 3B may also be narrowed in stages by continuously and gradually lowering the pair of grinding wheels 3A and 3B.

[0035] When the lowering and stopping are repeated, the lowering and stopping of the grinding wheel 3B can be controlled according to the load on the electric motors 9A and 9B that rotate the grinding wheels 3A and 3B. For example, after the grinding wheel 3B is lowered and stopped, the grinding wheel 3B is lowered again when the load on the electric motors 9A and 9B becomes lighter than a threshold value.

[0036] Fixing the gap between the grinding wheels 3A and 3B means fixing the gap between the pair of grinding wheels 3A and 3B without gradually narrowing it, and not lowering the grinding wheel 3B after that. Therefore, when gradually narrowing the gap between the grinding wheels 3A and 3B, if grinding wheel B is lowered and then stopped, and the lowering and stopping are repeated, the gap between the grinding wheels 3A and 3B is not fixed except for the final stop.

[0037] Heavy grinding is performed until the coil spring S reaches a length equal to the target length plus a predetermined additional length. This length can be detected based on the distance between the grinding wheels 3A and 3B. The additional length is the length that will be ground away by light grinding. At the end of heavy grinding, the length detector 17 is activated.

[0038] The length detector 17 is disposed above the support table 13 and has a contact 17a that can be raised and lowered. The contact 17a comes into contact from above with the coil spring S that passes over the support table 13. The length detector 17 can measure the length of the coil spring S according to the vertical height of the contact 17a.

[0039] The storage table 5 is a holding unit that holds the coil spring S and passes the coil spring S between the pair of grinding wheels 3A and 3B multiple times. Note that the holding unit can be any type, such as a robot arm or other holder, as long as it can be moved between the pair of grinding wheels 3A and 3B and outside the pair of grinding wheels 3A and 3B.

[0040] The storage table 5 of this embodiment is formed in a disk shape and is supported so as to be rotationally driven by an electric motor 19. That is, the electric motor 19 is coupled to an output shaft 21 that passes through the support table 13 so that the storage table 5 rotates integrally with the electric motor 19.

[0041] The receiving table 5 is held at a position above and spaced apart from the support table 13. The receiving table 5 receives a plurality of coil springs S, each of which passes through the table from top to bottom.

[0042] Specifically, the storage table 5 has a plurality of storage holes 5a. The storage holes 5a are provided in the vertical direction along the rotation axis of the storage table 5. The coil spring S stored in the storage holes 5a passes through the storage holes 5a, and both ends thereof protrude upward and downward from the storage table 5.

[0043] These multiple storage holes 5a are arranged in a ring shape along the rotation direction of the storage table 5. In this embodiment, the multiple storage holes 5a are lined up in the radial direction at predetermined intervals around the circumference of the storage table 5, thereby forming multiple rings with different diameters. Each ring-shaped storage hole 5a is located on an imaginary circle whose center is concentric with the storage table 5.

[0044] It is possible to provide two or more storage tables 5, and in this case, the multiple storage tables 5 may be configured to be positioned at a polishing position and a standby position and be used by switching between them.

[0045] The sprayer 7 sprays the mist M onto the end face SF of the coil spring S before or after the coil spring S passes between the grinding wheels 3A and 3B. In this embodiment, when the storage table 5 rotates clockwise in FIG. 1, the sprayer 7 sprays the mist M after the coil spring S passes between the grinding wheels 3A and 3B. Note that the sprayer 7 may be positioned as shown by the two-dot chain line in FIG. 1, or the storage table 5 may be rotated counterclockwise, so that the mist M is sprayed onto the coil spring S before it passes between the grinding wheels 3A and 3B.

[0046] The sprayer 7 of this embodiment is configured to include a blower 23 and a mist generator 25. However, the sprayer 7 may be a general one having a spray nozzle or the like.

[0047] The blower 23 has an intake port 23a and an outlet port 23b. The blower 23 sucks in mist M generated by the mist generator 25 together with air through the intake port 23a and discharges the sucked mist M from the outlet port 23b. The blower 23 is disposed above the support table 13, with the outlet port 23b facing downward. As a result, the mist M discharged from the outlet port 23b is sprayed onto the upper end face SF of the coil spring S on the support table 13.

[0048] The mist generator 25 is, for example, a spray gun, and has a spray nozzle 25a that emits a mist M of the cooling medium. The spray nozzle 25a is directed toward the intake port 23a of the blower 23. The mist generator 25 may also generate the mist M by ultrasonic waves.

[0049] The cooling medium can be a well-known coolant emulsion for metalworking. However, the cooling medium may also be water. The mist M evaporates when it comes into contact with the end surface SF of the coil spring S. Parameters of the mist M, such as particle size, speed, and spray angle, can be set appropriately depending on the heat generation amount of the coil spring S, etc.

[0050] Control unit 27 is a computer that controls each part of polishing apparatus 1. Below, the control of control unit 27 and the polishing method as the operation of polishing apparatus 1 will be described.

[0051] [Polishing method] 3 is a flowchart showing a polishing method according to the first embodiment of the present invention. Note that for the structure of the polishing apparatus 1, refer to FIGS.

[0052] In the polishing apparatus 1 of this embodiment, first, an unpolished coil spring S is accommodated on the accommodation table 5. The accommodation of this coil spring S can be performed by an appropriate mechanism such as a well-known robot arm under the control of the control unit 27.

[0053] When a predetermined number of unpolished coil springs S are accommodated, the control unit 9 controls the pair of grinding wheels 3A and 3B and the accommodation table 5 to polish the end faces SF of the coil springs S. In the polishing of this embodiment, as shown in FIG. 3, first, mist spraying onto the coil springs S starts (step S41), and heavy polishing of the coil springs S starts (step S42).

[0054] That is, the control unit 9 rotates the accommodation table 5 and the pair of grinding wheels 3A and 3B, thereby circulating the coil spring S between the support table 13 and the pair of grinding wheels 3A and 3B.

[0055] As a result, the coil spring S held on the storage table 5 is passed sequentially between the pair of grinding wheels 3A and 3B. After passing between the pair of grinding wheels 3A and 3B, the coil spring S passes between the pair of grinding wheels 3A and 3B again in accordance with the rotation of the storage table 5. In this way, the coil spring S is passed between the pair of grinding wheels 3A and 3B multiple times.

[0056] As each coil spring S passes through the pair of grinding wheels 3A and 3B, the end face SF of each coil spring S comes into contact with the grinding wheels 3A and 3B, respectively. This causes the end face SF of each coil spring S to be polished. The polishing here is heavy polishing performed by gradually narrowing the gap between the grinding wheels 3A and 3B. Along with this polishing, the control unit 27 causes the sprayer 7 to spray mist M onto the end face SF of the coil spring S after it has passed between the grinding wheels 3A and 3B.

[0057] The mist M is sprayed only onto the upper end face SF of each coil spring S. In this case, the mist M itself is sprayed only onto the upper end face SF, but the sprayed mist M may reach parts of the coil spring S other than the upper end face SF depending on parameters such as the degree of diffusion. Note that the mist M may also be sprayed onto both end faces SF of the coil spring S.

[0058] The sprayed mist M adheres to the upper end surface SF of the coil spring S, whose temperature has risen due to grinding, and vaporizes. At this time, the end surface SF of the coil spring S is cooled by the heat of vaporization being absorbed. On the other hand, the lower end surface SF of the coil spring S is in contact with the support table 13 outside the space between the grinding wheels 3A and 3B, and is therefore cooled by heat exchange with the support table 13.

[0059] When the heavy polishing of the coil spring S is completed, light polishing of the coil spring S is started (step S43). At this time, spraying of the mist M onto the coil spring S is completed (step S45).

[0060] Therefore, the mist M is sprayed only during heavy polishing. The spraying of the mist M may start after the start of heavy polishing and during heavy polishing. The spraying of the mist M may end before the end of heavy polishing, or during light polishing that is performed after heavy polishing and before the end of light polishing. In other words, the spraying of the mist M only needs to be performed during at least a part of the heavy polishing.

[0061] In this way, in the polishing method of this embodiment, polishing of the end surface SF of the coil spring S can be continued after the spraying of the mist M is completed. In particular, in the polishing method of this embodiment, light polishing of the end surface SF of the coil spring S is performed after the spraying of the mist M is completed.

[0062] By polishing after the spraying of the mist M is completed, even if the mist M does not evaporate but remains as a liquid cooling medium on the coil spring S, the remaining liquid cooling medium can be evaporated.

[0063] In this embodiment, measurement of the length of the coil spring S begins upon completion of spraying of the mist M (step S44). That is, the control unit 27 activates the length detector 17. The activated length detector 17 lowers the contact 17a to contact the upper end face SF of the coil spring S rotated by the storage table 5. The length of the coil spring S is detected according to the position of the contact 17a.

[0064] Then, when the light grinding of the coil spring S is completed (step S46), the length measurement of the coil spring S is also completed (step S47). That is, based on the length detected by the length detector 17, the control unit 27 terminates the grinding of the coil spring S and also terminates the length measurement of the coil spring S when the coil spring S reaches a target length. That is, the control unit 27 stops the rotation of the grinding wheels 3A and 3B and the storage table 5. Note that the grinding of the coil spring S may be terminated by raising the grinding wheel 3B and moving it away from the coil spring S.

[0065] In this manner, in this embodiment, by spraying the mist M onto the end face SF of the coil spring S after (or before) it passes between the grinding wheels 3A and 3B, it is possible to easily cool the end face SF of the coil spring S. By this cooling, in this embodiment, it is possible to increase the grinding allowance and increase the rotation speed of the grinding wheels 3A and 3B while suppressing deformation, discoloration, etc. of the coil spring S, thereby improving the productivity of the coil spring S.

[0066] The sprayed mist M evaporates when it adheres to the end surface SF of the coil spring S, eliminating the need to discard the cooling medium and making it easier to cool the end surface SF of the coil spring S. Furthermore, if the coil spring S is made of steel, it is possible to prevent the cooling medium from remaining on the coil spring S and prevent rust on the coil spring S. This makes it possible to use water as the cooling medium, making it easier to cool the end surface SF of the coil spring S.

[0067] In this embodiment, by continuing to polish the end surface SF of the coil spring S after spraying of the mist M has finished, even if the sprayed mist M remains as a liquid cooling medium on the coil spring S, the remaining cooling medium can be vaporized. Therefore, in this embodiment, it is possible to more reliably eliminate the need for disposal of the cooling medium and suppress rusting of the steel coil spring S.

[0068] The polishing in this embodiment includes heavy polishing, which is performed while gradually narrowing the gap between the grinding wheels 3A and 3B, and light polishing, which is performed after the heavy polishing while fixing the gap between the grinding wheels 3A and 3B. The mist M is sprayed during at least part of the heavy polishing.

[0069] Therefore, the end surface SF of the coil spring S can be reliably cooled during heavy polishing, which generates a larger amount of heat, and the productivity of the coil spring S can be improved.

[0070] When the mist M is sprayed only during heavy polishing, light polishing can be used to reliably prevent the cooling medium from remaining on the end surface SF of the coil spring S. In particular, when the spraying of the mist M is completed together with heavy polishing, the end surface SF of the coil spring S can be more reliably cooled during heavy polishing, and light polishing can be used to reliably prevent the cooling medium from remaining on the end surface SF of the coil spring S.

[0071] Furthermore, because the amount of heat generated at the end surface SF of the coil spring S during light polishing is less than during heavy polishing, if any cooling medium remains in the coil spring S after heavy polishing is completed, this remaining cooling medium can sufficiently cool the end surface SF of the coil spring S. Furthermore, even if there is no remaining cooling medium, the temperature rise at the end surface SF of the coil spring S due to light polishing is small, so defects such as changes in the hardness or mechanical properties of the coil spring S or deformation of the coil shape can be suppressed or prevented.

[0072] In this embodiment, the coil spring S is circulated between the support table 13 and the pair of grinding wheels 3A and 3B. This circulation causes the coil spring S to pass between the pair of grinding wheels 3A and 3B multiple times, and the mist M is sprayed only onto the end face SF located above the coil spring S.

[0073] Therefore, in this embodiment, the lower end surface SF of the coil spring S can be cooled by the support table 13, so by cooling only the upper end surface SF of the coil spring S with the mist M, both end surfaces SF of the coil spring S can be reliably cooled. [Explanation of symbols]

[0074] 1 Polishing equipment 3A, 3B whetstone 5. Storage table (holding section) 7 Sprayer 13 Support Table 23 Blower 25 Mist Generator 27 Control Unit S coil spring SF end face M Mist

Claims

1. passing the coil spring between a pair of grinding wheels a plurality of times to grind each end surface of the coil spring with the grinding wheels; spraying a mist onto the end surface of the coil spring before or after the coil spring passes between the grinding wheels; Polishing method.

2. The polishing method of claim 1, The polishing is continued after the spraying of the mist is completed. Polishing method.

3. The polishing method of claim 2, The polishing includes heavy polishing performed while gradually narrowing the interval between the grindstones, and light polishing performed after the heavy polishing while fixing the interval between the grindstones, The mist is sprayed during at least a portion of the heavy polishing. Polishing method.

4. The polishing method of claim 3, The mist is sprayed only during the heavy polishing. Polishing method.

5. The polishing method according to claim 3 or 4, The spraying of the mist ends together with the heavy polishing. Polishing method.

6. The polishing method according to any one of claims 1 to 3, With the pair of grinding wheels facing each other from above and below, the coil spring is circulated between a support table disposed adjacent to one of the pair of grinding wheels located below and the pair of grinding wheels, and the coil spring passes between the pair of grinding wheels a plurality of times by this circulation; The mist is sprayed only onto an end surface located above the coil spring. Polishing method.

7. a pair of grinding stones that grind the end faces of the coil springs that pass through; a holding part that holds the coil spring and passes the coil spring between the pair of grinding wheels a plurality of times; a sprayer that sprays mist onto an end surface of the coil spring before or after the coil spring passes between the grinding wheels; A polishing device comprising:

8. 8. The polishing apparatus of claim 7, the holding unit continues the operation of passing the coil spring between the pair of grinding wheels after the spraying of the mist is completed. Polishing equipment.

9. 9. The polishing apparatus of claim 8, The pair of grinding wheels are supported so that the distance between them can be changed, and heavy grinding is performed while the distance between them is narrowed in stages, and after the heavy grinding, the distance between them is fixed and light grinding is performed, The sprayer sprays the mist over at least a portion of the heavy polishing. Polishing equipment.

10. 10. The polishing apparatus of claim 9, The sprayer sprays the mist only during the heavy polishing. Polishing equipment.

11. 11. The polishing apparatus according to claim 9 or 10, The sprayer stops spraying the mist together with the heavy polishing. Polishing equipment.

12. 10. The polishing apparatus according to claim 8 or 9, a support table disposed adjacent to one of the pair of grinding wheels located below the other in a state where the pair of grinding wheels are opposed to each other vertically; the holding portion circulates the coil spring between the support table and the pair of grinding wheels, The sprayer sprays the mist only onto an end face located above the coil spring. Polishing equipment.

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