Attenuation mechanism for jack and machining method with use of the same

Abstract

To suppress deformation and ensure required accuracy of machining of even a surface with a wide processing width where a machining load becomes high.SOLUTION: A work-piece 50 is supported on a work table 4 of a machine tool in a cantilevered state, a jack 3 with an upper end contacting a rear face on a free end 51 side of the work-piece 50, to which an attenuation mechanism 10 for jack is attached, is arranged on a rear face side of the free end 51 side of the work-piece 50, and in the state that the attenuation mechanism 10 for jack is brought into contact with the rear face on the free end 51 side of the work-piece 50, a surface of the work-piece 50 supported on the work table 4 in the cantilevered state is machined while suppressing vibration of a machined surface 53 of the work-piece 50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a damping mechanism for a jack used during machining by a machine tool or the like, and a machining method using the same. [Background technology]

[0002] Conventionally, when machining such as cutting the cantilevered portion of a workpiece using a machine tool, the required accuracy of dimensions and roughness may not be achieved due to increased vibrations.

[0003] The vibration increases because the moment caused by the load from the machining process exceeds the rigidity of the workpiece, causing greater deformation.

[0004] Therefore, if the machining load is reduced and the rigidity of the workpiece is prioritized, the deformation will be smaller, and therefore the vibration will also be smaller.

[0005] However, lowering the machining load increases the machining time and reduces productivity, making this method impractical.

[0006] In order to solve this problem, it is known to provide a double-end support structure by installing a jack on the rear side of the free end of the cantilever of the workpiece, which reduces the rigidity of the workpiece and reduces deformation of the processed portion.

[0007] Although not this type of jack, for example, a ram cushion for a seal press using a disc spring is known, as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Utility Model Application Publication No. 50-132793 Summary of the Invention [Problem to be solved by the invention]

[0009] However, while the method of supporting both ends with a jack is effective for downward deformation in which the jack exerts its function, it is ineffective for upward deformation in which the upper end of the jack is not in contact.

[0010] This is because the reaction force generated when a downward machining load acts on the jack is released in an upward direction.

[0011] As a result, on surfaces with a wide machining width where the machining load is high, deformation becomes large and the required precision cannot be ensured, so it has been necessary to reduce the machining load and lower productivity.

[0012] The present invention has been made in consideration of the above points, and its purpose is to suppress deformation and ensure the required machining precision even on surfaces with a wide machining width where the machining load is large. [Means for solving the problem]

[0013] In order to achieve the above object, in the present invention, the free end side of the workpiece is machined while being supported by a jack equipped with a damping mechanism.

[0014] Specifically, the first invention is directed to a jack damping mechanism that is attached to the upper end of a jack that contacts the back surface of the free end side of a workpiece to be machined, The jack damping mechanism includes: A cap portion attached to an upper end of the jack; a contact portion attached to the cap portion in a non-removable state and capable of sliding up and down; and an elastic member provided between the cap portion and the abutment portion.

[0015] According to the above configuration, the jack equipped with the jack damping mechanism having an elastic member is placed on the back surface of the free end of the workpiece, and the surface of the workpiece is machined while supporting the back surface of the free end, thereby suppressing downward deformation of the workpiece. The machining load at that time is absorbed by the elastic member, suppressing the upward reaction force. Therefore, the upward deformation that would occur when the top end of the jack is not in contact with the workpiece can also be effectively suppressed.

[0016] In the second invention, in the first invention, the elastic member is a spring washer, the abutment portion has an insertion portion that is inserted into a through hole formed in an upper surface of the cap portion, The spring washer is detachably provided between an upper surface of the cap portion and a peripheral edge of the insertion portion in a state where the spring washer is attached to the outer periphery of the insertion portion.

[0017] According to the above-mentioned configuration, the spring washer, which is easily available and easily replaceable, is stably attached, thereby providing a damping mechanism for a jack that is inexpensive and simple in structure and assembly.

[0018] In the third invention, in the second invention, A locking washer having an outer diameter larger than the through hole in the cap portion is fastened to the lower end of the insertion portion with a fastening bolt and fixed to the lower end of the insertion portion with the bolt head of the fastening bolt, so that the insertion portion is configured to be able to slide up and down inside the through hole while being prevented from falling out.

[0019] According to the above configuration, the spring washer can be easily replaced by removing and attaching the fastening bolt, so that a damping mechanism for a jack having a simple configuration and easy maintenance can be obtained.

[0020] The machining method of the fourth invention comprises: The workpiece is supported in a cantilevered manner on the worktable of the machine tool. A jack having a damping mechanism attached to an upper end thereof that abuts against the back surface of the free end side of the workpiece is disposed on the back surface side of the free end side of the workpiece; With the damping mechanism in contact with the back surface of the free end side of the workpiece, the surface of the workpiece supported in a cantilevered state on the work table is machined while suppressing vibration of the machining surface of the workpiece.

[0021] According to the above configuration, the jack equipped with the jack damping mechanism having an elastic member is placed on the back surface of the free end side of the workpiece, and the surface of the workpiece is machined while supporting the back surface of the free end side, thereby suppressing downward deformation of the workpiece. The machining load at that time is absorbed by the elastic member, suppressing the upward reaction force. Therefore, upward deformation that would cause the top end of the jack to be out of contact is also effectively suppressed. Effect of the Invention

[0022] As described above, according to the present invention, deformation does not become large even on a wide machining width surface where the machining load is high, and the required accuracy can be ensured, so that machining productivity can be maintained. [Brief description of the drawings]

[0023] [Figure 1] 1 is a front view showing a machining method according to an embodiment of the present invention; [Diagram 2] 1 is an enlarged cross-sectional view showing a damping mechanism for a jack according to an embodiment of the present invention. [Diagram 3] 1 is a table showing test results comparing examples of the present invention with comparative examples. [Figure 4] 2 according to a modified example of the embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0025] 1 shows a state in which a machining method is carried out using a jack 3 equipped with a jack damping mechanism 10 according to an embodiment of the present invention. For example, in this embodiment, the jack 3 equipped with the jack damping mechanism 10 is used in machining by an NC machine tool. However, the application of the present invention is not limited to this.

[0026] Specifically, the jack damping mechanism 10 of this embodiment is attached to the upper end of a jack 3 that abuts against a back surface 52 on the free end 51 side of a workpiece 50 to be machined. Fig. 1 shows, for example, a state in which a milling tool 1 as a tool of an NC machine tool is rotated by a tool axis 2 to cut a surface (machined surface 53) of the workpiece 50.

[0027] As shown enlarged in Fig. 2, this jack damping mechanism 10 includes a cap portion 11 that is attached to the upper end of the jack 3. The cap portion 11 has a shape that matches the shape of the upper end of the jack 3, and is detachable from the upper end of the jack 3 with bolts, screws, or the like (not shown). For example, the cap portion 11 has a cylindrical portion 11b that has a through hole 11a at its upper end, and a flange portion 11c provided at the lower end of the cylindrical portion 11b. The cap portion 11 is formed by cutting out round steel such as gray cast iron FC250, but may be formed by casting or forging in the case of mass production.

[0028] The jack damping mechanism 10 is attached to the cap portion 11 in a state where it is prevented from coming off, and includes an abutment portion 12 that can slide up and down. The abutment portion 12 has, for example, a cylindrical insertion portion 12a that is inserted into a through hole 11a formed on the upper surface of the cap portion 11. An annular recess 12b is formed on the outer periphery of this insertion portion 12a. In this embodiment, the abutment surface 12c of the cap portion 11 that abuts against the back surface 52 of the workpiece 50 is flat. A female screw portion 12d is formed at the center of the lower surface of the insertion portion 12a. The abutment portion 12 is also formed by cutting out round steel of, for example, gray cast iron FC250, but may be formed by casting or forging in the case of mass production.

[0029] A spring washer 13 serving as an elastic member is attached between the cap portion 11 and the contact portion 12. The spring washer 13 may be, for example, a general-purpose spring washer for an M20 bolt. The annular recess 12b may be formed to have an appropriate depth so that the spring washer 13 can be attached thereto.

[0030] When the spring washer 13 is attached to the outer periphery of the insertion portion 12a, it is detachably provided between the upper surface of the cap portion 11 and the peripheral edge of the insertion portion 12a in the annular recess 12b (the bottom surface of the annular recess 12b in Figure 2, i.e., the back surface of the abutment surface 12c).

[0031] With the insertion portion 12a inserted into the through hole 11a of the cap portion 11, a retaining washer 14 having an outer diameter larger than that of the through hole 11a is fastened to the lower end of the insertion portion 12a with a fastening bolt 15, and is fixed to the lower end of the insertion portion 12a with a bolt head 15a of the fastening bolt 15. In this state, by providing an appropriate space in the vertical direction between the upper surface of the retaining washer 14 and the periphery of the through hole 11a of the cylindrical portion 11b, the insertion portion 12a is configured to be able to slide up and down within the range of this space while being prevented from slipping out of the inside of the through hole 11a.

[0032] Next, the operation of the machining method according to this embodiment will be described.

[0033] First, as shown in FIG. 1, a workpiece 50 that is relatively large in size and is formed, for example, from the bed of a machine tool, is supported in a cantilever manner on the workpiece table 4 of the machine tool.

[0034] Next, the jack 3 having the jack damping mechanism 10 attached to its upper end that abuts against the back surface 52 on the free end 51 side of the workpiece 50 is placed below the back surface 52.

[0035] Next, with the contact surface 12c of the jack damping mechanism 10 in contact with the back surface 52 on the free end 51 side, the machined surface 53 is machined while suppressing vibration of the free end 51 of the workpiece 50.

[0036] In this embodiment, the jack 3 provided with the jack damping mechanism 10 having the spring washer 13 is placed on the back surface of the free end 51 side of the workpiece 50, and the machined surface 53 of the workpiece 50 is machined while supporting the back surface 52 of the free end 51 side, thereby suppressing downward deformation of the workpiece 50. The machining load at that time is absorbed by the spring washer 13, suppressing the upward reaction force. As a result, the upper end of the jack 3 is out of contact, and upward deformation is also effectively suppressed.

[0037] In this embodiment, by using the spring washer 13, which is easily available and easily replaceable, it is possible to obtain an inexpensive jack damping mechanism 10 that is simple in configuration, assembly, and maintenance.

[0038] --Example-- Below, experiments were carried out to confirm the effect of the above-mentioned jack damping mechanism 10. A milling tool with a diameter of 125 mm was used as the tool 1. The rotation speed of the tool 1 was 300 rpm, and the feed rate was 400 mm / min. The cutting diameter direction was 25 mm to 75 mm. Comparative Example 1 is a case where cutting is performed without using the jack 3. Comparative Example 2 is a case where machining is performed using a conventional jack without the jack damping mechanism 10 attached. And Example 1 is a case where machining is performed using the jack damping mechanism 10 according to the embodiment of the present invention.

[0039] As shown in FIG. 3, milling was performed in two cases, one in which the machining width of the machined surface 53 was narrow, 25 mm, and the other in which the machining width was wide, 135 mm, and the amount of deformation in each case was measured.

[0040] When the processing width is relatively narrow at 25 mm, the deformation was 30.2 μm in Comparative Example 1, which did not use the jack 3, but was reduced to 9.1 μm in Comparative Example 2, which used the jack 3. However, in Example 1, which was equipped with the jack damping mechanism 10, the deformation amount was further reduced to only 0.4 μm, and a significant reduction in the deformation amount was confirmed.

[0041] Furthermore, when the processing width is large at 135 mm, the deformation amount is large at 215.8 μm in Comparative Example 1, but is rather large at 243.6 μm in Comparative Example 2. This is considered to be because a large reaction force is generated at the upper end of the jack 3, which increases the amount of upward deformation. However, in Example 1, the deformation amount is significantly reduced to only 1 μm.

[0042] Therefore, according to the machining method using the jack damping mechanism 10 of this embodiment, deformation does not become large even on the wide machining surface 53 where the machining load is high, and the required accuracy can be ensured, so that the productivity of the machining can be maintained.

[0043] -Variations- Fig. 4 shows a modified example of a damping mechanism for a jack 10' according to an embodiment of the present invention, which differs from the above embodiment in that the shape of the contact portion 12' is different. In this modified example, the same parts as those in Figs. 1 and 2 are denoted by the same reference numerals and detailed description thereof will be omitted.

[0044] That is, in this modified example, the shape of the contact surface 12c' of the contact portion 12' is tapered such that the outer diameter decreases toward the top. Because the tip is sharp, the contact area between the machined surface 53 of the workpiece 50 and the back surface 52 is small.

[0045] In this modified example, as in the above embodiment, deformation does not become large even on the wide machined surface 53 where the machining load is high, and the required accuracy can be ensured, so that machining productivity can be maintained.

[0046] (Other embodiments) The present invention may be configured as follows with respect to the above embodiment.

[0047] That is, the machining method of the present invention is not particularly limited as long as it is a machining method in which the cantilevered workpiece 50 is machined while being pressed downward. Examples of the machining include lathe machining, milling, drilling, and polishing.

[0048] In the above embodiment, the elastic member is a spring washer, but it may be a general-purpose compression coil spring, leaf spring, etc. General-purpose products are easy to obtain, inexpensive, and easy to replace.

[0049] It should be noted that the above-described embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0050] 1 tool 2 Tool axis 3. Jack 10,10' Damping mechanism for jack 11 Cap section 11a Through hole 11b Cylindrical part 11c Flange part 12,12' Contact part 12a Insertion part 12b Circular recess 12c,12c' Contact surface 13 Spring washer 14 Lock washer 15 Fastening bolt 15a Bolt head 50 Work 51 Free end 52 Back side 53 Surface (machined surface)

Claims

1. A jack damping mechanism that is attached to the upper end of a jack that contacts the back surface of the free end side of a workpiece to be machined, A cap portion attached to an upper end of the jack; a contact portion attached to the cap portion in a non-removable state and capable of sliding up and down; An elastic member is provided between the cap portion and the abutment portion. A damping mechanism for a jack.

2. the elastic member is a spring washer, the abutment portion has an insertion portion that is inserted into a through hole formed in an upper surface of the cap portion, The spring washer is detachably provided between an upper surface of the cap portion and a peripheral edge of the insertion portion in a state where the spring washer is attached to the outer periphery of the insertion portion.

2. The damping mechanism for a jack according to claim 1.

3. A retaining washer having an outer diameter larger than the through hole of the cap portion is fastened to the lower end of the insertion portion by a fastening bolt and fixed to the lower end of the insertion portion by the bolt head of the fastening bolt, so that the insertion portion is configured to be able to slide up and down inside the through hole while being prevented from falling out.

3. A damping mechanism for a jack according to claim 2.

4. The workpiece is supported in a cantilevered manner on the worktable of the machine tool. A jack having a damping mechanism attached to an upper end thereof that abuts against the back surface of the free end side of the workpiece is disposed on the back surface side of the free end side of the workpiece; With the damping mechanism in contact with the back surface of the free end side of the workpiece, the surface of the workpiece supported in a cantilevered state on the work table is machined while suppressing vibration of the machining surface of the workpiece. A machining method comprising the steps of:

Images