JP7375626B2 - Tightening equipment and machine tools - Google Patents

Description

The present invention relates to a tightening device and a machine tool, and particularly to a tightening device for tightening and fixing a hollow workpiece in a machine tool that performs rough machining and finishing machining of the hollow workpiece, and a machine tool using the same.

When machining the inner surface of a hollow workpiece, a tool attached to the main shaft of a general-purpose machining center is used, for example. Then, the hollow workpiece is fixed using a processing jig. The processing jig includes, for example, bolts and nuts for applying clamping force to the presser foot.

In the above machining jig, it is necessary to change the clamping force from the nut to match the machining accuracy. Specifically, the force for clamping the hollow workpiece is increased during rough machining, and the force for clamping the hollow workpiece is decreased during finishing machining (for example, see Patent Document 1).
The reason why the clamping force is increased during rough machining is because the machining allowance is large, so unless the clamp is tightened strongly, the workpiece will move during machining. The reason for reducing the clamping force during finishing machining is that if the clamping force is strong, the workpiece will be elastically deformed and distorted, resulting in a decrease in machining accuracy, flatness, surface roughness, etc. The reason why the clamping force can be reduced during finishing machining is that the machining allowance is small, so the workpiece will not move even if the clamping force is weak.

Furthermore, an automatic clamping force switching mechanism (changing the spring force by turning a screw) is known (for example, see Patent Document 2).

Japanese Patent Application Publication No. 2005-103731 Utility Model Publication No. 02-027807

Conventionally, before finishing finishing, the processing machine was stopped, the worker used a wrench to loosen the nut on the processing jig, and then tightened the nut to generate a weak clamping force. Therefore, it has not been possible to automatically perform rough machining and finishing machining continuously.

An object of the present invention is to enable a clamping device to automatically change the magnitude of clamping force between rough machining and finishing machining of a hollow workpiece.

A plurality of aspects will be described below as means for solving the problem. These aspects can be arbitrarily combined as necessary.

A tightening device according to an aspect of the present invention is a device for tightening a hollow work, and includes a rod screw, a nut member, an operating tool, and a controller.
The bar screw extends in the tightening direction.
The nut member includes a cylindrical portion, a pressing member, a compression spring, a load transmission member, and an operating member. The cylindrical part has a threaded part that threads into the rod screw and an internal space. The holding member is a member that is disposed on the hollow work side of the internal space and applies a load to the hollow work. A compression spring is arranged in the interior space. The load transmission member is movable between a contact position where the load from the cylindrical portion is transmitted to the presser member while in contact with the presser member, and a non-contact position where the load transfer member is not in contact with the presser member. The operating member is used to move the load transmitting member from a contact position to a non-contact position.
The operating tool operates the operating member.
During rough machining, the load transmission member is in the contact position, and when the cylindrical portion is rotated relative to the bar screw, a large first load acts on the holding member from the load transmission member.
During finishing processing, the controller moves the load transmitting member from the contact position to the non-contact position by controlling the movement of the operating tool. As a result, the first load from the load transmission member no longer acts on the holding member, and the load acting on the holding member becomes a small second load acting as a spring force from the compression spring.
In this device, a compression spring is built into the nut member, and the load from the nut member is switched using an operating tool. In other words, the magnitude of the clamping force is automatically changed between rough machining and finishing machining of a hollow workpiece.

A machine tool according to another aspect of the present invention includes the aforementioned tightening device and a tool spindle.
The tool spindle can selectively hold either a cutter for cutting a hollow workpiece or an operating tool.
The operating member may be a screw that is screwed into the load transmission member and rotated by an operating tool driven by a tool main shaft.
In this machine tool, the operating member is easily operated by the tool spindle and the operating tool.

The tightening device may further include a guide member that is fixed to the cylindrical portion and guides movement of the load transfer member when the load transfer member moves from the contact position to the non-contact position.
In this device, the guide member stabilizes the movement of the load transfer member when it moves to the non-contact position.

In the tightening device according to the present invention, the clamping force is automatically changed between rough machining and finishing machining of a hollow workpiece.

FIG. 2 is a schematic side view of a machining center. FIG. 3 is a schematic perspective view of a hollow workpiece and a workpiece fixing jig. A schematic perspective view of a workpiece fixing jig. A plan view of a workpiece fixing jig. A cross-sectional view of a workpiece fixing jig. A cross-sectional view of a workpiece fixing jig. A cross-sectional view of a workpiece fixing jig. A cross-sectional view of a workpiece fixing jig. A schematic plan view of a workpiece fixing jig. A schematic plan view of a workpiece fixing jig. A sectional view of a workpiece fixing jig and an operating tool. FIG. 2 is a block diagram showing a control configuration of a machining center.

1. First Embodiment (1) Machining Center A machining center 1 (an example of a machine tool) will be described using FIG. FIG. 1 is a schematic side view of a machining center.
The machining center 1 is of a so-called horizontal type in which a rotation center axis X of a tool spindle 11 (described later) extends in the horizontal direction.
The machining center 1 includes a base 7 that extends in the front-rear direction (left-right direction in FIG. 1), and a main body that is placed on one end side of the base 7 (the right side in FIG. 1, hereinafter referred to as the rear side). It has 9 and.

The machining center 1 has a tool spindle 11. The tool main shaft 11 is provided in the main body portion 9 so as to be rotatable around a rotation center axis X extending in the horizontal direction. A cutter 12 is attached to the tool spindle 11 for cutting the hollow workpiece 3, that is, for cutting a thrust surface or a spherical surface.
The main body portion 9 is movable back and forth by a guide rail 13 attached to the base 7. Further, the tool spindle 11 is movable up and down by a guide rail 15 attached to the main body portion 9. Therefore, the tool spindle 11 is movable both forward and backward and up and down.

The machining center 1 further includes a tool magazine 17 that accommodates various tools.
The machining center 1 has an auto tool changer 19. The auto tool changer 19 attaches each tool housed in the tool magazine 17 to the tool spindle 11 and replaces the tool attached to the tool spindle 11 with a tool housed in the tool magazine 17.

The hollow workpiece 3 is, for example, a component of a machine tool, and has a hollow portion 3a that accommodates a shaft portion.

The machining center 1 includes a table 21 located at a front position on the base 7, which rotates around a rotation axis Z extending in the vertical direction or moves linearly. A workpiece fixing jig 31 that holds a hollow workpiece 3 to be machined is disposed on the table 21 .

(2) Work Fixing Jig The work fixing jig 31 will be explained using FIGS. 2 to 11. FIG. 2 is a schematic perspective view of a hollow workpiece and a workpiece fixing jig. FIG. 3 is a schematic perspective view of the workpiece fixing jig. 4 to 8 are plan views of the workpiece fixing jig. 9 and 10 are schematic plan views of the workpiece fixing jig. FIG. 11 is a cross-sectional view of the workpiece fixing jig and the operating tool.

The work fixing jig 31 (an example of a tightening device) is a device that tightens and fixes the hollow work 3.
The workpiece fixing jig 31 presses four upper corners 3b of the hollow workpiece 3 downward.

One of the four workpiece fixing jigs 31 will be explained below.
As shown in FIG. 2, the workpiece fixing jig 31 includes a first support 33a and a second support 33b that extend upward from the table 21. The second support column 33b is arranged in line with the first support column 33a on the outside away from the hollow workpiece 3. Specifically, the first pair of second pillars 33b and the second pair of second pillars 33b are arranged on sides away from each other with respect to each first pillar 33a.
The work fixing jig 31 has a holding plate 37, as shown in FIG. The holding plate 37 extends in the horizontal direction, has a first end in contact with the upper corner 3b of the hollow workpiece 3, and a second end in contact with the upper end of the second support column 33b. This prevents the second end of the presser plate 37 from lowering. A nut member 41 (described later) is attached to an intermediate portion or a portion near the second end of the holding plate 37. Therefore, when a downward load is applied from the nut member 41 to the holding plate 37, the holding plate 37 applies a clamping force to the hollow workpiece 3.

As shown in FIGS. 7 and 8, the first support column 33a is provided with a rod screw 35 extending upward from its upper end.
The workpiece fixing jig 31 has a nut member 41, as shown in FIG. As shown in FIGS. 7 and 8, the nut member 41 is attached to the bar screw 35, and includes a cylindrical portion 43, a pressing member 45, a compression spring 47, a load transmission member 49, and an operating member 51. has.

The cylindrical part 43 has a threaded part 43a that threads into the upper part of the rod screw 35. The cylindrical portion 43 has an internal space 43b that is open downward.
The holding member 45 is a member disposed on the hollow workpiece 3 side of the internal space 43b to apply a load to the hollow workpiece 3. The holding member 45 is a cylindrical member disposed around the bar screw 35, and is movable up and down with respect to the cylindrical portion 43 within a predetermined range. The holding member 45 is fixed to the above-mentioned holding plate 37 or is in contact with the holding plate 37 from above.

The compression spring 47 is arranged in the internal space 43b. Compression spring 47 is a coil spring. The compression spring 47 has an upper end supported by the upper downward surface 43c of the cylindrical portion 43, and a lower end supported by the upper surface 45a of the pressing member 45. The compression spring 47 is set to apply a weak second load to the pressing member 45.
The cylindrical portion 43 is composed of a cylindrical first member 43A and a lid-shaped second member 43B including a threaded portion 43a, both of which are detachably fixed by bolts 44. This allows the compression spring 47 and other members to be placed within the internal space 43b. Further, a spring force adjusting member such as a shim can be arranged between the first member 43A and the second member 43B.

The load transmission member 49 is a block or a plate-like piece, and is supported by the cylindrical portion 43. The load transmission member 49 has two contact positions (FIGS. 5, 7, and 9) where it is in contact with the pressing member 45 and transmits the load from the cylindrical portion 43 to the pressing member 45, and a state where it is not in contact with the pressing member 45. It is movable between the non-contact position (FIGS. 8 and 10).
Specifically, the load transmission member 49 is supported so as to be movable only in the radial direction relative to the cylindrical portion 43. More specifically, the load transmission member 49 is slidably supported in a notch 43d that opens outward in the radial direction at one location in the circumferential direction of the cylindrical portion 43.
Further, the load transmitting member 49 is immovably circumferentially moved and radially outwardly removed when the load transmitting member 49 moves from the contact position to the non-contact position by the guide member 53 fixed to the cylindrical portion 43. It is supported in a way that makes it impossible. Therefore, the movement of the load transmission member 49 is stabilized. Specifically, the guide member 53 includes a pair of guide portions 53a that abut against the outer circumferential surface of the load transmission member 49, and a stopper 53b that connects the outer ends of the pair of guide portions 53a in the radial direction. ing.

The load transmission member 49 has an engaging portion 49a. The engaging portion 49a is provided at the radially inner end of the entire load transmitting member 49, and has a structure for engaging and disengaging the pressing member 45. Specifically, the engaging portion 49a has an arc shape in plan view.
As shown in FIGS. 7 and 9, the load transmission member 49 is located on the inside in the radial direction at the contact position, and the engaging portion 49a enters from the outside in the radial direction into the notch 43d formed in the cylindrical portion 43. The inner end lower surface 49b of the engaging portion 49a contacts or approaches the upward facing surface 45c at the lower part of the annular recess 45b formed in the upper part of the holding member 45 (in a position where they overlap in the vertical direction). At this time, the engaging portion 49a is close to or in contact with the outer peripheral surface of the annular recess 45b of the pressing member 45, as shown in FIG.
As shown in FIGS. 8 and 10, the load transmitting member 49 is located on the outside in the radial direction in the non-contact position, and the engaging portion 49a is removed radially outside from the notch 43d formed in the cylindrical portion 43. The inner tip lower surface 49b is radially removed from the upwardly facing surface 45c of the annular recess 45b. Note that the portion of the upward facing surface 45c of the annular recess 45b that the inner end lower surface 49b of the engaging portion 49a comes into contact with is a portion in the circumferential direction. Therefore, when the upward surface 45c of the annular recess 45b is worn out, the holding member 45 may be rotated as appropriate to change the portion that contacts the engaging portion 49a.

The operating member 51 is used to move the load transmitting member 49 from a contact position to a non-contact position. The operation member 51 is a release bolt that extends in the radial direction and is screwed into the screw hole 49c of the load transmission member 49.
The operating member 51 has a threaded portion 51a and a head portion 51b. The head 51b has a rectangular shape, for example. The tip of the threaded portion 51a is in contact with or close to a wall surface 43e formed in the cylindrical portion 43 and facing outward in the radial direction. In this state, when the operating member 51 rotates, the load transmitting member 49 moves radially outward.
The operating member 51 is rotated by an operating tool 73 driven by the tool spindle 11, as shown in FIG. The operating tool 73 is, for example, a universal socket that is provided with a large number of pins that are expandable and retractable. In this way, the operating member 51 is easily operated by the tool spindle 11 and the operating tool 73.

(3) Control configuration The control configuration of the machining center 1 will be explained using FIG. 12. FIG. 12 is a block diagram showing the control configuration of the machining center.
The machining center 1 has a controller 71.
The controller 71 is a computer having a processor (e.g., CPU), a storage device (e.g., ROM, RAM, HDD, SSD, etc.), and various interfaces (e.g., A/D converter, D/A converter, communication interface, etc.). It is a system. The controller 71 performs various control operations by executing programs stored in a storage unit (corresponding to part or all of the storage area of the storage device).
The controller 71 may be composed of a single processor, or may be composed of a plurality of independent processors for each control.
Part or all of the functions of each element of the controller 71 may be realized as a program executable by the computer system that constitutes the controller 71. In addition, a part of the functions of each element of the control section may be configured by a custom IC.

A tool spindle drive section 101, a rotary table drive section 103, and an auto tool changer drive section 105 are connected to the controller 71.
Although not shown, the controller 71 is connected to sensors for detecting the size, shape, and position of the hollow workpiece 3, sensors and switches for detecting the status of each device, and an information input device.

(4) Tightening before rough machining During rough machining, the load transmission member 49 is in the contact position as shown in FIGS. 5, 7, and 9. In this state, when the operator rotates the cylindrical portion 43 with respect to the bar screw 35, a large first load acts on the holding member 45 from the load transmission member 49. The magnitude of the first load is, for example, 100KN.

(5) Tightening before finishing processing The controller 71 performs tool exchange using the auto tool changer 19, and thereby attaches the operating tool 73 to the tool spindle 11.
The controller 71 moves the workpiece fixing jig 31 in front of the tool spindle 11 by rotating or linearly moving the table 5 .
During finishing processing, the controller 71 controls the movement of the operating tool 73 to move the load transmission member 49 from the contact position to the non-contact position. Specifically, the operating tool 73 rotates the operating member 51. Then, the tip of the threaded portion 51a of the operating member 51 rotates while being in contact with the wall surface 43e of the cylindrical portion 43, whereby the load transmitting member 49 moves radially outward. As a result, the inner end lower surface 49b of the engaging portion 49a of the load transmission member 49 comes off the upward surface 45c of the pressing member 45.
As shown in FIGS. 8 and 10, when the load transmission member 49 is moved to the non-contact position, the first load from the load transmission member 49 no longer acts on the pressing member 45, and the load acting on the pressing member 45 is compressed. A small second load acts as a spring force from the spring 47. The second load is, for example, 30KN.

When the above operation is performed a total of four times, the workpiece W is tightened with a weak force in all the workpiece fixing jigs 31.
As described above, in this workpiece fixing jig 31, the compression spring 47 is built into the cylindrical portion 43, and the load from the nut member 41 is switched by the operation tool 73. In other words, the magnitude of the clamping force is automatically changed between rough machining and finishing machining of the hollow workpiece 3.
In particular, since the magnitude of the clamping force is changed using the tool exchange function of the machining center 1, no special equipment is required and the operation is easy.
Furthermore, the workpiece fixing jig 31 can use the conventional first support 33a, second support 33b, bar screw 35, and presser plate 37 as they are, and simply change the conventional nut to the nut member 41, allowing two levels of clamping force. Implements a change mechanism. In this way, since the conventional jig is used as is, it is inexpensive. Further, the work fixing jig 31 realizes a two-stage clamping force changing mechanism without a power source using hydraulic pressure, electricity, or the like.

2. Features of the Embodiments The embodiments can also be explained as follows.
The workpiece fixing jig 31 (an example of a tightening device) is a device for tightening the hollow workpiece 3 (an example of a hollow workpiece), and includes a rod screw 35, a nut member 41, an operating tool 73, and a controller 71. There is.
The bar screw 35 (an example of a bar screw) extends in the tightening direction.
The nut member 41 (an example of a nut member) includes a cylindrical portion 43, a pressing member 45, a compression spring 47, a load transmission member 49, and an operating member 51. The cylindrical part 43 (an example of a cylindrical part) has a threaded part 43a that threads into the bar screw 35 and an internal space 43b. The holding member 45 (an example of a holding member) is a member that is arranged on the hollow workpiece 3 side of the internal space 43b and applies a load to the hollow workpiece 3. The compression spring 47 (an example of a compression spring) is arranged in the internal space 43b. The load transmitting member 49 (an example of a load transmitting member) has a contact position where it transmits the load from the cylindrical portion 43 to the presser member 45 while in contact with the presser member 45, and a non-contact position where it is not in contact with the presser member 45. It is movable between locations. The operating member 51 (an example of an operating member) is used to move the load transmitting member 49 from a contact position to a non-contact position.
The operating tool 73 (an example of an operating tool) operates the operating member 51.
During rough machining, the load transmission member 49 is in the contact position, and when the cylindrical portion 43 is rotated with respect to the bar screw 35, a large first load is applied from the load transmission member 49 to the holding member 45.
During finishing processing, the controller 71 (an example of a controller) moves the load transmission member 49 from the contact position to the non-contact position by controlling the movement of the operating tool 73. As a result, the first load from the load transmission member 49 no longer acts on the holding member 45, and the load acting on the holding member 45 becomes a small second load acting as a spring force from the compression spring 47.

In this workpiece fixing jig 31, a compression spring 47 is built into the nut member 41, and the load from the nut member 41 is switched by an operating tool 73. In other words, the magnitude of the clamping force is automatically changed between rough machining and finishing machining of the hollow workpiece 3.

3. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the invention. In particular, the multiple embodiments and modifications described in this specification can be arbitrarily combined as necessary.
In the embodiment described above, the operation member 51 was rotated in order to move the load transmission member to the non-contact position, but the method of moving the load transmission member is not particularly limited. For example, the load transmission member may be moved by directly pulling it radially outward.
The second support may be disposed diagonally outward from the corner of the hollow work with respect to the first support. In this case, the holding plate extends diagonally from the corner of the hollow workpiece.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to a tightening device that tightens and fixes a hollow workpiece in a machine tool that performs rough machining and finishing machining of the hollow workpiece.

1 : Machining center 3 : Hollow workpiece 3a : Hollow part 3b : Upper corner part 7 : Base 9 : Main body part 11 : Tool spindle 12 : Cutter 13 : Guide rail 15 : Guide rail 17 : Tool magazine 19 : Auto tool changer 21 : Table 31: Work fixing jig 33a: First support 33b: Second support 35: Bar screw 37: Holding plate 41: Nut member 43: Cylindrical portion 43a: Threaded portion 43b: Internal space 43c: Downward surface 43d: Cut Notch 45: Holding member 45a: Upper surface 45b: Annular recess 45c: Upward surface 47: Compression spring 49: Load transmission member 49a: Engagement portion 49b: Inner tip lower surface 51: Operating member 53: Guide member 71: Controller 73: Operating tool

Claims (4)

A tightening device for tightening a hollow workpiece,
A bar screw extending in the tightening direction,
a cylindrical part having a threaded part to be threaded onto the bar screw and an internal space; a holding member disposed on the hollow work side of the internal space to apply a load to the hollow work; and a holding member in the internal space. The arranged compression spring is movable between a contact position where the load from the cylindrical part is transmitted to the presser member while in contact with the presser member and a non-contact position where it is not in contact with the presser member. a nut member having a load transmission member; and an operation member used for moving the load transmission member from the contact position to the non-contact position;
an operating tool for operating the operating member;
During rough machining, the load transmission member is in the contact position, and when the cylindrical part is rotated with respect to the rod screw, a large first load is applied from the load transmission member to the holding member,
During finishing processing, the operation tool is controlled to move the load transmission member from the contact position to the non-contact position, so that the first load from the load transmission member no longer acts on the holding member; a controller, wherein the load acting on the pressing member becomes a small second load acting as a spring force from the compression spring;
Tightening device. The tightening device according to claim 1;
A cutter that performs cutting on the hollow workpiece, and a tool spindle that can selectively hold any of the operating tools,
The operating member is a machine tool that is threaded onto the load transmission member and is a screw rotated by the operating tool driven by the tool main shaft. The tightening device according to claim 1, further comprising a guide member fixed to the cylindrical portion and guiding movement of the load transfer member when the load transfer member moves from the contact position to the non-contact position. Device. The work according to claim 2, further comprising a guide member fixed to the cylindrical portion and guiding movement of the load transmission member when the load transmission member moves from the contact position to the non-contact position. machine.

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