Suction cup type workpiece fixing device for machine tools

Abstract

To ensure holding of a positioning state of a workpiece placed on a table in a chamfer machine.SOLUTION: A workpiece 5 is adsorbed and fixed on a table upper surface 9 by a vertically moving sucker 7. The sucker 7 is adsorbed in the workpiece in an adsorption recess 12 and has an air hole 15 formed in a center base 13 so as to communicate with the adsorption recess 12. The sucker 7 is stored in a sucker storage recess 16 opened in the table upper surface 9. The adsorption recess 12 of the sucker is positioned below a workpiece lower surface 19 in a state where the workpiece is placed on the table upper surface so as to cover an upper end opening 17 of the sucker storage recess 16. The workpiece lower surface 19 is absorbed on the upper end opening of a sucker storage part through suction at the air hole 15. In this state, the raised sucker sucks the workpiece lower surface. When the center base 13 is pulled downward in the sucked state, the workpiece is pulled downward via the sucker, and the workpiece is fixed on the table upper surface in a real adsorption state.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a suction cup-type workpiece fixing device for machine tools. [Background Art]

[0002] When performing machining such as chamfering with a milling cutter on a workpiece placed on a table of a machine tool, an example of a machine tool configured to fix the workpiece to the table by an air suction method is provided in Patent Document 1.

[0003] The machine tool includes a table on which a workpiece is placed, a clamping device disposed on a front side of the table, and a milling cutter disposed on the front side of the table for performing machining such as chamfering on the workpiece. The clamping device includes upper and lower clamping pieces that clamp, from above and below, an overhanging portion of the workpiece placed on the table that appropriately overhangs from a front edge of the table. Prior to performing the machining, the machine tool appropriately positions the workpiece placed on the table in the left-right direction and the front-rear direction, fixes the positioned workpiece to the table, then moves the table appropriately, and clamps the overhanging portion appropriately overhanging from the front edge of the table with the upper and lower clamping pieces. Then, in a workpiece clamping state where the upper and lower clamping pieces clamp the overhanging portion, the milling cutter performs machining on a workpiece portion to be processed which forms a front side of the clamped portion of the workpiece.

[0004] Machining is performed on one processing surface of the workpiece in a state where the overhanging portion is clamped as described above.

[0005] After machining of the one processing surface of the workpiece is completed, the clamping of the overhanging portion by the upper and lower clamping pieces is released. In this released state, the table is rotated 90 degrees to perform machining on a new processing surface.

[0006] Incidentally, the means for fixing the workpiece to the table described in Patent Document 1 is provided with shallow recesses on the front and rear of the upper surface of the table, and a number of ventilation holes are provided vertically on the bottom surface of the recesses. The upper ends of the ventilation holes open on the upper surface of the bottom surface, and their lower ends are connected to an air suction device for drawing in air.

[0007] After the required positioning of the workpiece placed on the table was completed, the workpiece was fixed to the table by sucking the air in the space formed between the recess and the underside of the workpiece.

[0008] However, conventionally, if the surface roughness and flatness of the workpiece's underside were not good enough, outside air would be drawn in, resulting in incomplete fixation. In particular, with thin-walled and warped workpieces, the space in the warped portion was in communication with the outside, causing poor contact between the workpiece and the table surface, making it impossible to fix the workpiece to the table.

[0009] If the fixing is incomplete in this way, after the required positioning of the workpiece placed on the table is completed, the fixing of the workpiece to the table may become uncertain due to the acceleration and deceleration of the table when the table starts moving forward as described above or when the table stops, or due to the acceleration and deceleration of the table when the table starts rotating 90 degrees as described above or when the table rotation stops, causing the workpiece on the table to shift from its set position. This leads to the problem that the workpiece cannot be machined accurately. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2012-106327 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention was developed in view of the aforementioned conventional problems, and aims to provide a suction cup type workpiece fixing device for a machine tool that can reliably maintain the positioning state when performing machining such as chamfering on a workpiece that has been positioned and placed on a table, thereby enabling high-precision machining such as chamfering. [Means for solving the problem]

[0012] To solve the aforementioned problems, the present invention employs the following means. That is, the first embodiment of the suction cup type workpiece fixing device for a machine tool according to the present invention is a suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the table surface by suction via a vertically moving suction cup, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. The peripheral edge of the suction recess is adsorbed to the lower surface of the workpiece. As the central base of the suction cup is elastically pulled downward, a downward tension is obtained on the workpiece via the suction cup, thereby fixing the workpiece to the table surface in a permanent suction state. It is designed to be so, The bottom of the suction cup housing recess is provided with a series of vertical guide holes in the vertical direction. An air tube is inserted through the guide vertical hole, and the air tube is guided by the guide vertical hole and can move up and down. The air tube has an air passage in its axial direction, the upper part of which is connected to the air hole of the suction cup, and the air passage is connected to an air supply source that supplies negative or positive pressure air to the air hole. Furthermore, a piston is provided at the lower part of the air pipe so that the suction cup can be moved up and down, the piston can move up and down within a cylinder provided in the table, the up and down movement of the piston is configured to be performed by controlling the supply of positive pressure air or negative pressure air to upper and lower ports provided at the upper and lower parts of the cylinder that are in communication with the cylinder, and the upper port is also in communication with the air passage, and the suction cup adsorption type workpiece fixing device for a machine tool is characterized by having the above configuration. (1) When the upper end of the suction cup housing recess is covered by the workpiece and the piston is in contact with the bottom of the cylinder or has moved toward the bottom, negative pressure air is supplied to the upper port, thereby obtaining the preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. (2) While the pre-adsorption state is maintained with negative pressure air supplied to the upper port, positive pressure air is supplied to the lower port to raise the air pipe, causing the suction cup to rise and the peripheral edge of the adsorption recess to adhere to the lower surface of the workpiece. (3) When negative air is supplied to the lower port while the workpiece is in the suctioned state, the piston descends, and the central base of the suction cup is elastically pulled downward while the workpiece remains in the suctioned state, resulting in a downward tension on the workpiece via the suction cup, thereby fixing the workpiece to the table surface in this suctioned state. (4) By supplying negative pressure air to the lower port and positive pressure air to the upper port, the workpiece is released from the suction state by the suction cup.

[0013] According to a second aspect of the suction cup adsorption-type workpiece fixing device for a machine tool of the present invention, in the first aspect, the suction cup accommodating recess The workpiece is placed on the table so as to cover the upper end opening, and the suction recess of the suction cup is located below the lower surface of the workpiece. Positive-pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby allowing the workpiece to float and move on the table surface. is characterized by the following.

[0014] According to a third aspect of the suction cup adsorption-type workpiece fixing device for a machine tool of the present invention, A suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the table surface by adsorption via a vertically moving suction cup, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. As the peripheral portion of the suction recess remains attached to the lower surface of the workpiece, the central base of the suction cup is elastically pulled downward, thereby creating a downward tension on the workpiece via the suction cup, and thereby fixing the workpiece to the upper surface of the table in this suction state. The workpiece is placed on the table so as to cover the upper end opening of the suction cup housing recess, and the suction recess of the suction cup is located below the lower surface of the workpiece. Positive-pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby enabling the workpiece to float and move on the table surface.

[0015] According to a fourth aspect of the suction cup adsorption-type workpiece fixing device for a machine tool of the present invention, A suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the table surface by adsorption via a vertically moving suction cup, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. As the peripheral portion of the suction recess remains attached to the lower surface of the workpiece, the central base of the suction cup is elastically pulled downward, thereby creating a downward tension on the workpiece via the suction cup, and thereby fixing the workpiece to the upper surface of the table in this suction state. The bottom of the suction cup housing recess is provided with a series of vertical guide holes in the vertical direction. An air tube is inserted through the guide vertical hole, and the air tube is guided by the guide vertical hole and can move up and down. The air tube has an air passage in its axial direction, the upper part of which is connected to the air hole of the suction cup, and the air passage is connected to an air supply source that supplies negative or positive pressure air to the air hole. Furthermore, the air tube is configured to move up and down by a vertical movement device so that the suction cup can be moved up and down. The workpiece is placed on the table so as to cover the upper end opening of the suction cup housing recess, and the suction recess of the suction cup is located below the lower surface of the workpiece. Positive-pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby enabling the workpiece to float and move on the table surface. [Effects of the Invention]

[0016] In the case of a suction cup type workpiece fixing device for a machine tool according to the present invention, since it is constructed using a suction cup made of rubber with good adhesion, it is possible to reliably maintain the positioning state when performing machining such as chamfering on a workpiece that has been positioned and placed on the table as required, thereby providing a suction cup type workpiece fixing device for a machine tool that enables high-precision machining such as chamfering. [Brief explanation of the drawing]

[0017] [Figure 1] This is a plan view illustrating a suction cup type workpiece fixing device for a machine tool according to the present invention. [Figure 2] This is a plan view showing the arrangement of suction cups on a table. [Figure 3] This is a cross-sectional view illustrating the configuration of a suction cup type workpiece fixing device for a machine tool. [Figure 4] This is an explanatory diagram illustrating the range of vertical movement of the suction cup. [Figure 5] This is an explanatory diagram illustrating the preliminary suction state of the suction cup. [Figure 6] This is an explanatory diagram illustrating the state in which the suction cup rises and its peripheral edge adheres to the underside of the workpiece, while the suction cup is in a pre-adhesion state. [Figure 7] This is an explanatory diagram illustrating the optimal suction state of the suction cup. [Figure 8] This is an explanatory diagram illustrating the state when the suction cup has been released from its adhesive state. [Figure 9]This is a side view showing the upper and lower clamping pieces gripping the workpiece while the milling cutter performs chamfering. [Figure 10] This is a plan view showing the process of performing measurements for workpiece positioning using a movable measuring instrument. [Modes for carrying out the invention] [Examples]

[0018] In Figures 1 and 2, the suction cup type workpiece fixing device (hereinafter also referred to as the workpiece fixing device) 1 for a machine tool according to the present invention is applied to a machine tool 2, for example, a chamfering machine 2a that performs chamfering on a workpiece 5 on a table 3 with a milling cutter 6, and fixes the workpiece 5 to the table surface 9 by suction via vertically moving suction cups 7. In this embodiment, as shown in Figure 2, the suction cups 7 are provided at each of the four corners 10, 10, 10, 10 of the table 3, which has an octagonal shape in plan view, and are positioned on both sides in plan view.

[0019] As shown in Figures 3 and 4, the suction cup 7 is designed to adhere to the lower surface 19 of the workpiece 5 by an adsorption recess 12 in a skirt-shaped adsorption portion 11 that widens towards the upper end for vacuum adsorption, and an air hole 15 communicating with the adsorption recess 12 is provided in the central base portion 13 of the adsorption portion 11. The suction cup 7 is housed in a suction cup housing recess 16 that is provided at a required location on the table 3 and is open on the upper surface 9 of the table, with the adsorption recess 12 opening upward. Furthermore, with the workpiece 5 placed on the table 3 so as to cover the upper end opening 17 of the suction cup housing recess 16, the suction recess 12 of the suction cup 7 is configured to be in a lower position, as shown in Figure 4, where it is located below the lower surface 19 of the workpiece 5 (hereinafter also referred to as the workpiece lower surface). The suction cup 7 in this lower position can be raised to an upper position that protrudes above the upper surface 9 of the table, as shown by the dashed line in Figure 4. In this embodiment, it is possible to raise it by about 1 mm.

[0020] Then, as shown in Figure 5, when the suction at the air hole 15 acts with the suction recess 12 in the lower position, a preliminary suction state 20 is obtained in which the lower surface 19 of the workpiece is adsorbed to the upper end opening 17 of the suction cup housing recess 16. In this preliminary suction state 20, as the suction cup 7 rises to the upper position shown by the dashed line in Figure 4, as shown in Figure 6, the peripheral portion 21 of the suction recess 12 presses upward against the lower surface 19 of the workpiece, while preventing the workpiece 5 from lifting off the table surface 9 due to the workpiece suction action in the preliminary suction state 20 (Figure 5). This pressing action causes the peripheral portion to be adsorbed to the lower surface 19 of the workpiece.

[0021] Furthermore, as shown in Figure 6, while maintaining the suction state 22 (Figure 6), the central base 13 of the suction cup 7 is elastically pulled downward, thereby creating a downward tension on the workpiece 5 via the suction cup 7. This causes the workpiece 5 to be fixed to the table surface 9 in this suction state 23.

[0022] In this embodiment, as shown in Figure 4, the suction cup receiving recess 16 has a circular recess 25 that can accommodate the central base portion 13 of the suction cup 7. An enlarged circular recess 27, which widens towards the top, is provided at the upper end 26 of the circular recess 25, sharing an axis with the circular recess 25, and can accommodate the skirt-shaped suction portion 11 of the suction cup 7. Furthermore, a guide vertical hole 29, smaller in diameter than the circular recess 25, is provided at the bottom center of the circular recess 25, sharing an axis with the circular recess 25.

[0023] As shown in Figure 4, an air pipe 30 is inserted through the guide vertical hole 29, and the air pipe 30 is guided by the guide vertical hole 29 and can move up and down. The air pipe 30 is provided with an air passage 31 in the axial direction, and the upper part of the air passage 31 is connected to the air hole 15 of the suction cup 7 via a connecting pipe member 32, and the air passage 31 is an air supply source (not shown) that supplies negative pressure air or positive pressure air to the air hole 15. Connected.

[0024] As shown in Figure 4, the air pipe 30 is moved up and down by the vertical movement device 28 so that the suction cup 7 can be moved up and down. In this embodiment, the vertical movement device 28 is provided with a piston 33 at the lower part of the air pipe 30. The piston 33 can move up and down within a cylinder 35 provided inside the table 3. The vertical movement of the piston 33 is configured to be performed by controlling the supply of positive pressure air or negative pressure air to upper and lower ports 36 and 37 provided at the upper and lower parts of the cylinder 35 that are in communication with the cylinder 35, and the upper port 36 is also in communication with the air passage 31.

[0025] Next, the operation of the suction cup type workpiece fixing device 1 having the above configuration will be explained with reference to Figures 4 to 7. The arrows shown in Figures 5 to 8 indicate the direction of air movement. Figure 4 shows the initial state, where the workpiece 5, which has been positioned on the table 3 in the left-right and front-back directions as required and placed on the table surface 9, is shown just before being fixed to the table surface 9 by suction, and the upper end opening 17 of the suction receiving recess 16 is covered by the workpiece 5.

[0026] Figure 5 shows the preliminary suction state 20 in which the lower surface 19 of the workpiece is adsorbed to the upper opening 17 of the suction cup housing recess 16 by supplying negative pressure air to the upper port 36 while the upper end opening 17 is covered by the workpiece 5 and the piston 33 is in contact with the bottom 34 of the cylinder 35.

[0027] Figure 6 shows the state in which, while the pre-adsorption state 20 (Figure 5) in which negative pressure air is supplied to the upper port 36 is maintained, positive pressure air is supplied to the lower port 37 to raise the air pipe 30, and consequently the suction cup 7 rises and the peripheral portion 21 of the suction recess 12 is adsorbed to the lower surface 19 of the workpiece.

[0028] Figure 7 shows the state in which, while the workpiece is in the suctioned state, negative pressure air is supplied to the lower port 37 to lower the piston 33, and while the workpiece is in the suctioned state, the central base 13 of the suction cup 7 is elastically pulled downward, thereby creating a downward tension on the workpiece 5 via the suction cup 7, and the workpiece 5 is fixed to the table top surface 9 in this suctioned state 23.

[0029] Figure 8 shows the state in which the suction cup 7 is released from its fixed position by supplying negative pressure air to the lower port 37 and positive pressure air to the upper port 36. By releasing the fixation, the workpiece 5 can be removed from the table 3.

[0030] Next, we will describe the case where the workpiece fixing device 1 according to the present invention is applied to a chamfering machine 2a, including the positioning step of the workpiece 5 on the table 3, the suction cup adsorption step of the workpiece 5 to correctly maintain the positioned state, the clamping step of the workpiece 5 while the position is maintained, and the subsequent chamfering step of the workpiece 5.

[0031] First, as shown in Figures 1 and 9, the chamfering machine 2a comprises a table 3 on which a workpiece 5 is placed, a positioning device 40 (Figure 1) for positioning the workpiece 5 on the table 3, a clamping device 41 disposed on the front side of the table 3, and a milling cutter 6 disposed on the front side of the table 3 for processing the workpiece 5. As shown in Figure 9, the clamping device 41 has upper and lower clamping pieces 45 and 46 that clamp the protruding portion 43 of the workpiece 5 placed on the table surface 9, which extends from the front edge 42 of the table 3. With the upper and lower clamping pieces 45 and 46 clamping the protruding portion 43, the milling cutter 6 is configured to perform chamfering on the workpiece portion 47 (Figures 9(A) and 9(B)) that forms the front side of the clamped portion of the workpiece 5.

[0032] In the chamfering machine 2a, the table 3 has a horizontal table surface 9 and can be rotated as required around its vertical axis by an indexing device.

[0033] The lower clamping piece 46 can take on an elevated position that protrudes above the table surface 9, a lowered position lower than the table surface 9, and a clamping position that contacts the lower surface 19 of the workpiece 5. When the lower clamping piece 46 is in the elevated position, the workpiece 5 placed on the table surface 3 is advanced, bringing the front surface of the workpiece 5 into contact with the lower clamping piece 46, thereby forming the protruding portion 43. After the table 3 has advanced the required amount with the lower clamping piece 46 in the lowered position, the lower clamping piece 46 rises to take on the clamping position, and the protruding portion 43 is clamped by the upper and lower clamping pieces 45 and 46.

[0034] (1) Regarding the workpiece positioning process on the table The workpiece 5 placed on the table 3 has a required thickness and exhibits a square, rectangular, or octagonal shape in plan view. The workpiece shown in Figure 1 is rectangular in shape and, in plan view, has sides of 150 to 500 mm, for example, a square with sides of 300 mm.

[0035] Figure 1 is a plan view showing the workpiece 5 placed on the table 3. The workpiece 5 is suspended from the table surface 9 with the table 3 separated behind the upper and lower clamping pieces 45, 46 (Figure 9). As shown in Figures 1 and 4, the lower surface 19 of the workpiece 5 covers the upper end opening 17 of the suction cup receiving recesses 16 arranged at required intervals on the table 3. Prior to fixing the workpiece, the workpiece 5 is positioned as required on the table 3. This positioning is performed using the positioning device 40 (which includes a positioning tool 49 and a measuring instrument 50 as shown in Figure 1).

[0036] Figure 1 shows the process of roughly positioning in the left-right and front-back directions. This positioning is performed by pressing one corner 52 of the workpiece 5 against a right-angle positioning section 51 formed by the positioning piece 49a of the advanced positioning tool 49 and the lower clamping piece 42 (Figure 9) which extends in a direction perpendicular to the axial direction of the positioning tool 49.

[0037] Figure 10 shows the process of positioning the workpiece 5 using a measuring instrument 50 so that the front surface 5a of the workpiece 5 is correctly parallel to the left-right direction (the horizontal movement direction of the milling cutter 6) F.

[0038] Figure 10 shows the procedure for making appropriate corrections based on the measurement results from the measuring instrument 50 in order to improve the accuracy of the chamfering process. In this embodiment, as shown in Figure 10, the measuring instrument 50 is provided with a movable probe 50a that can move forward and backward on a movable frame 54 that is movable in the left-right direction (the direction in which the milling cutter moves) F. The measuring instrument 50 is moved forward with the probe 50a positioned on the left and right ends of the workpiece 3, and the tip 50b of the probe 50a is brought into contact with the front surface 5a of the workpiece 5. This measures the distance between the tip 50b of the probe 50 in the retracted state and the front surface 5a at the left and right ends. If the two distances are not the same, the table 3 is rotated by the required angle around its axis to adjust so that the two distances are the same. This allows the workpiece 5 to be positioned on the table 3 so that the front surface 5a of the workpiece 5 is correctly parallel to the left-right direction F prior to clamping.

[0039] By the way, when performing the operation of pressing the corner portion 52 (Figure 1) against the right-angle positioning portion 51 (Figure 1), it is preferable to supply positive-pressure air into the suction recess 12 from the air hole 15 (Figure 4) of the suction cup 7 and eject the air from the upper end opening 17 of the suction cup housing recess 16. This allows the workpiece 5 to be levitated and moved on the table surface 9, making it easier to move the workpiece 5 on the table surface 9. This movement of the workpiece 5 can be performed smoothly and without obstruction because the peripheral portion 21 (Figure 4) of the suction recess 12 of the suction cup 7 does not protrude from the upper end opening 17 of the suction cup housing recess 16.

[0040] Subsequently, as shown in Figure 10, the workpiece 5 is positioned on the table 3 prior to clamping by making appropriate corrections based on the measurement results from the measuring instrument 50.

[0041] (2) Regarding the suction cup adsorption process of the workpiece The workpiece 5, positioned in this manner, is fixed to the table 3 according to the process described above with reference to Figures 3-7.

[0042] (3) Workpiece clamping process After the workpiece 5 is positioned in this manner, the table 3 is advanced by the required amount (for example, 10 to 20 mm) taking into consideration the size (depth) of the chamfer. Then, as shown in Figure 9, the workpiece 5 is clamped by the overhang portion 43 being held between the upper and lower clamping pieces 45 and 46.

[0043] (4) Regarding the chamfering process of the workpiece With the workpiece clamped, the milling cutter 6 performs chamfering on the edge portion of the workpiece 47, for example, as shown in Figure 9.

[0044] The chamfering process according to the present invention is carried out through the above steps, and according to the present invention, the two problems described in Patent Document 1 can be solved, and machining, such as chamfering, can be performed on a wide range of workpieces. The two problems here are the first and second problems described below. (1) The first problem If the surface roughness and flatness of the workpiece's underside are not good enough, it can draw in outside air, resulting in incomplete fixation to the table. (2) Second problem In the case of thin-walled and warped workpieces, the space in the warped portion is in communication with the outside, resulting in poor contact between the workpiece and the table surface, making it impossible to fix the workpiece to the table.

[0045] The reason why the workpiece fixing device 1 according to the present invention can solve the first problem is that, because the workpiece fixing device is made of rubber and uses a suction cup with good adhesion, the influence of the roughness and flatness of the workpiece is mitigated compared to conventional devices.

[0046] Furthermore, the reason why the workpiece fixing device 1 can solve the second problem is that the present invention has the following configuration. That is, "By the suction acting at the air hole 15, the lower surface 19 of the workpiece is adsorbed by the upper end opening 17 of the suction cup housing recess 16, creating the preliminary adsorption state 20 (Figure 5). In this preliminary adsorption state 20, the suction cup 7 rises (for example, rises by about 1 mm). The workpiece adsorption action in this preliminary adsorption state 20 prevents the workpiece 5 from floating up from the table top surface 9, while the peripheral portion 21 of the adsorption recess 12 presses the lower surface 19 of the workpiece upward and is adsorbed to the lower surface 19. In this adsorption state, the central base 13 of the suction cup 7 is elastically pulled downward, creating a downward tension on the workpiece 5 via the suction cup 7, thereby fixing the workpiece 5 to the table top surface 9 in this final adsorption state."

[0047] This allows even thin-walled and warped workpieces to be securely attached to the table by the upward action of the suction cups, enabling precise machining of the workpieces. [Explanation of symbols]

[0048] 1. Workpiece fixing device 2 Machine tools 3 tables 5 Work 6 milling machine 7 sucker 9 Tabletop 11 Adsorption part 12 Adsorption recess 13 Central base 15 air vents 16 Suction cup receiving recess 17 Top opening 20 Pre-adsorption state 21 Peripheral portion 23 Adsorption State 29 Guide vertical hole 30 Air tubes 31 Airway 33 pistons 35 cylinders 36 ports above 37 The port below 45 Upper clamping piece 46 Lower clamping piece

Claims

1. A suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the table surface by adsorption via a vertically moving suction cup, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. As the peripheral portion of the suction recess remains attached to the lower surface of the workpiece, the central base of the suction cup is elastically pulled downward, thereby creating a downward tension on the workpiece via the suction cup, and thereby fixing the workpiece to the upper surface of the table in this suction state. The bottom of the suction cup housing recess is provided with a series of vertical guide holes in the vertical direction. An air tube is inserted through the guide vertical hole, and the air tube is guided by the guide vertical hole and can move up and down. The air tube has an air passage in its axial direction, the upper part of which is connected to the air hole of the suction cup, and the air passage is connected to an air supply source that supplies negative or positive pressure air to the air hole. Furthermore, a piston is provided at the lower part of the air pipe so that the suction cup can be moved up and down, the piston can move up and down within a cylinder provided in the table, the up and down movement of the piston is configured to be performed by controlling the supply of positive pressure air or negative pressure air to upper and lower ports provided at the upper and lower parts of the cylinder that are in communication with the cylinder, and the upper port is also in communication with the air passage, and the suction cup adsorption type workpiece fixing device for a machine tool is characterized by having the above configuration. (1) When the upper end of the suction cup housing recess is covered by the workpiece and the piston is in contact with the bottom of the cylinder or has moved toward the bottom, negative pressure air is supplied to the upper port, thereby obtaining the preliminary suction state in which the lower surface of the workpiece is adsorbed to the upper end opening of the suction cup housing recess. (2) While the pre-adsorption state is maintained with negative pressure air supplied to the upper port, positive pressure air is supplied to the lower port to raise the air pipe, causing the suction cup to rise and the peripheral edge of the adsorption recess to adhere to the lower surface of the workpiece. (3) When negative air is supplied to the lower port while the workpiece is in the suctioned state, the piston descends, and the central base of the suction cup is elastically pulled downward while the workpiece remains in the suctioned state, resulting in a downward tension on the workpiece via the suction cup, thereby fixing the workpiece to the table surface in this suctioned state. (4) By supplying negative pressure air to the lower port and positive pressure air to the upper port, the workpiece is released from the suction state by the suction cup.

2. The suction cup type workpiece fixing device for a machine tool according to claim 1 is configured such that the workpiece is placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located below the lower surface of the workpiece, and positive pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby allowing the workpiece to float and move on the table surface.

3. A suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the upper surface of a table by suction via a suction cup that moves up and down, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. As the peripheral portion of the suction recess remains attached to the lower surface of the workpiece, the central base of the suction cup is elastically pulled downward, thereby creating a downward tension on the workpiece via the suction cup, and thereby fixing the workpiece to the upper surface of the table in this suction state. A suction cup type workpiece fixing device for a machine tool, characterized in that the workpiece is placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located below the lower surface of the workpiece, and positive-pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby enabling the workpiece to float and move on the table surface.

4. A suction cup type workpiece fixing device for a machine tool that fixes a workpiece to the table surface by suction via a vertically moving suction cup, The suction cup is made of rubber and is designed to adhere to the workpiece through an adsorption recess in a skirt-shaped adsorption portion for vacuum adsorption, with an air hole in the central base of the adsorption portion that communicates with the adsorption recess, and the suction cup is housed in a suction cup housing recess that is open on the upper surface of the table and is provided at a required location on the table with the adsorption recess opening upward. With the workpiece placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located on the lower side of the lower surface of the workpiece. In this state, the suction from the air hole acts, resulting in a preliminary suction state in which the lower surface of the workpiece is attracted to the upper end opening of the suction cup housing recess. In this pre-adhesion state, the suction cup is designed to rise, preventing the workpiece from lifting off the table surface due to the workpiece adsorption action in this pre-adhesion state, while the peripheral portion of the adsorption recess presses upward against the lower surface of the workpiece, causing the peripheral portion to adhere to the lower surface of the workpiece. As the peripheral portion of the suction recess remains attached to the lower surface of the workpiece, the central base of the suction cup is elastically pulled downward, thereby creating a downward tension on the workpiece via the suction cup, and thereby fixing the workpiece to the upper surface of the table in this suction state. The bottom of the suction cup housing recess is provided with a series of vertical guide holes in the vertical direction. An air tube is inserted through the guide vertical hole, and the air tube is guided by the guide vertical hole and can move up and down. The air tube has an air passage in its axial direction, the upper part of which is connected to the air hole of the suction cup, and the air passage is connected to an air supply source that supplies negative or positive pressure air to the air hole. Furthermore, the air tube is configured to move up and down by a vertical movement device so that the suction cup can be moved up and down. A suction cup type workpiece fixing device for a machine tool, characterized in that the workpiece is placed on the table so as to cover the upper end opening of the suction cup housing recess, the suction recess of the suction cup is located below the lower surface of the workpiece, and positive-pressure air is supplied into the suction recess from the air hole, causing air to be ejected from the upper end opening of the suction cup housing recess, thereby enabling the workpiece to float and move on the table surface.

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