JP2012106327A - Machine tool including clamp device for clamping overhung part of workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the operation of placing a workpiece on a table with satisfactory working efficiency, and to highly accurately machine a workpiece overhung part overhung from the table while preventing chattering vibration.SOLUTION: A machine tool includes: a table 3 on which a workpiece 2 is placed; a clamp device 5 which is arranged at the front side of the table 3; and tools 6 and the like which are arranged at the front side of the table 3 to perform machining such as chamfering on the workpiece 2. The clamp device 5 is equipped with upper and lower clamping pieces 10, 11 that vertically clamp the overhung part 9 of the workpiece 2 overhung from the front edge 28 of the table 3, and placed on the upper face 15 of the table 3. In a workpiece clamped state so that the overhung part 9 is clamped by the upper and lower clamping pieces 10, 11, the tools 6 perform machining on a part 13 to be machined which constitutes the front side of the clamped part of the workpiece 2.

Description

  The present invention relates to a machine tool including a clamping device that clamps a projecting portion of a workpiece. More specifically, while the work can be placed on the table with good workability, the projecting part of the work projecting from the front edge of the table is securely clamped from above and below to form the front side of the clamped part. The present invention relates to a machine tool including a clamping device that clamps a projecting portion of a workpiece, which can perform various machining operations such as cutting on a workpiece portion in a stable state.

  After the workpiece is placed on the table as required, the workpiece is clamped between the pressing tool and the table by pressing the placed workpiece against the table with the pressing tool. On the other hand, as an example of a conventional machine tool that performs a required cutting process such as chamfering, those described in Patent Document 1, Patent Document 2, and Patent Document 3 are provided.

  In this type of machine tool, since the workpiece pressing device is disposed above the center of the table, the workpiece pressing device becomes an obstacle when the workpiece is placed on the upper surface of the table in a required state. The workpiece could not be suspended directly on the center of the upper surface. For this reason, there is a trouble that the work must be moved laterally to a required position on the upper surface after the work is hung down from the end of the upper surface of the table. There was a problem. Also, when removing the workpiece after machining, the workpiece pressing device becomes an obstacle, and there is a problem that workability is poor because it takes time to remove the workpiece.

  In addition, since the workpiece is clamped between the pressing tool and the table and the clamped workpiece is machined, the size of the workpiece is restricted by the size of the table. If a workpiece that is larger than the table is placed on the upper surface of the table and machining such as cutting is performed on the part that protrudes from the table, there is a problem that chatter vibration is generated and machining accuracy is deteriorated. It was.

JP-A-6-226577 JP-A-5-245712 Japanese Utility Model Publication No. 3-15041

  The present invention has been developed in view of the above-described conventional problems, and can perform work placing work on a table with good workability, and can be applied to a work projecting portion projecting from the table. The machine can be machined satisfactorily while suppressing vibrations, and the machined part can be accurately machined even for large workpieces that protrude from the table. An object of the present invention is to provide a machine tool including a clamping device that clamps a workpiece overhanging portion that enables machining of a larger workpiece.

In order to solve the above problems, the present invention employs the following means.
That is, a machine tool (hereinafter referred to as a machine tool) having a clamping device for clamping a projecting portion of a workpiece according to the present invention includes a table on which the workpiece is placed, and a clamping device disposed on the front side of the table. And a tool arranged on the front side of the table for processing the workpiece, and the clamping device projects from the front edge of the table of the workpiece placed on the upper surface of the table An upper and lower holding piece for holding the overhanging portion from above and below is provided, and the upper and lower holding pieces hold the overhanging portion in a work clamp state, and the tool forms a front side of the holding portion of the work. The machined portion is machined.

  In the machine tool, the table can move in the front-rear direction, and the lower gripping piece comes into contact with the lower position of the workpiece, the raised position protruding above the upper surface of the table, the lowered position lower than the upper surface. The workpiece placed on the upper surface of the table is advanced in a state where the lower clamping piece is in the raised position, and the front side of the workpiece is placed on the lower clamping piece. The projecting portion is formed so that the lower gripping piece is in the lowered position, and the table is advanced by a required amount while the lower gripping piece is in the lowered position. It is good to comprise so that it may raise so that a clamping position may be exhibited and the said overhang | projection part may be clamped with the said upper and lower clamping pieces.

  In the machine tool, the front edge of the table facing the lower gripping piece may be formed as a linear edge extending in the left-right direction.

  One of the preferred embodiments of the machine tool is preferably configured as follows. That is, the tool performs cutting on the workpiece by moving linearly in the left-right direction, and the table can rotate about the vertical axis and move in the front-rear direction, With the lower holding piece in the raised position, the work placed on the upper surface of the table is advanced, and the front surface of the work is brought into contact with the lower holding piece to form the overhang portion. After that, the lower holding piece is made to exhibit the lowered position, and in this state, the measuring element of the measuring instrument that can move in the left-right direction is seen in the left-right direction of the front surface of the workpiece. The probe moves relatively toward the front surface at the one end side position, and the tip of the probe contacts the front surface, so that the first tip between the tip and the front surface is moved. 1 distance can be measured, The stator moves to the other end side of the front surface of the workpiece when viewed in the left-right direction, and at the other end side position, the probe moves relatively toward the front surface, and the tip of the probe is A second distance between the tip and the front surface can be measured by contacting the front surface. When the measured first distance is different from the second distance, the table is moved to the axis line. By rotating the required amount around, the distance between the front end and the front surface at the one end side position and the distance between the front end and the front surface at the other end side position are corrected. Thereafter, the table is advanced by a required amount, and the projecting portion is clamped by upper and lower clamping pieces so that the workpiece is clamped. In the workpiece clamping state, the tool is , The covered It is preferable to configured to perform a machining coated portion.

  Other than the preferred embodiment of the machine tool, the following configuration is preferable. That is, the tool performs cutting on the workpiece by moving linearly in the left-right direction, and the table can rotate about the vertical axis and move in the front-rear direction, With the lower holding piece in the raised position, the work placed on the upper surface of the table is advanced, and the front surface of the work is brought into contact with the lower holding piece to form the overhang portion. After that, the lower holding piece is made to exhibit the lowered position, and in this state, the measuring element of the measuring instrument that can move in the left-right direction is seen in the left-right direction of the front surface of the workpiece. The first distance between the tip and the front surface is measured by moving to one end side and detecting the reflected light reflected from the front surface irradiated with light from the probe at the one end side position. And the measurement Is moved to the other end side of the workpiece as viewed in the left-right direction, and at the other end side position, a light beam is irradiated from the measuring element and reflected light reflected by the front surface is detected by a detection unit. So that the second distance between the tip and the front surface can be measured, and when the measured first distance is different from the second distance, the table is rotated by the required amount around the axis. As a result, the distance between the front end and the front surface at the one end side position and the distance between the front end and the front surface at the other end side position are corrected to be equal. Then, the table is moved forward by a required amount, and the workpiece is clamped by clamping the overhanging portion with upper and lower clamping pieces. In the workpiece clamping state, the tool is moved to the workpiece portion. In the machine It is preferable to configured to perform a process.

  In each of the machine tools, a positioning portion is provided that can be positioned on one side portion of the clamping device as viewed in the left-right direction and can contact an adjacent surface adjacent to the front surface, and the lower gripping piece is in the raised position. In this state, the front surface of the workpiece placed on the table is brought into contact with the lower gripping piece and the adjacent surface is brought into contact with the positioning portion. It is good to make it possible to perform positioning.

The present invention has the following excellent effects.
(1) The workpiece clamp in the machine tool according to the present invention is not a pressing tool that presses the workpiece toward the upper surface of the table as in the conventional case. Instead of the workpiece placed on the table, This is performed by holding the protruding portion protruding from the front edge with upper and lower holding pieces. Therefore, according to the present invention, it is possible to perform work placing work on the table and work removing the processed work from the table with good workability. As a result, productivity can be improved.

(2) According to the present invention, in a state where the overhanging portion protruding from the front edge portion of the table is clamped by the upper and lower holding pieces, machining can be performed on the workpiece that forms the front side of the holding portion. . In this way, since the workpiece is clamped at the portion to be processed, even when a relatively large workpiece is placed on a relatively small table, chatter vibration is suppressed against the workpiece and a good machine is achieved. Processing can be performed. As a result, even a conventional small machine tool with a small table can be processed from a relatively small workpiece to a relatively large workpiece, and the range in terms of the size of the workpiece can be expanded. And in this way, in order to clamp a workpiece | work in the case of a to-be-processed part, there also exists an advantage which should just clamp with the minimum clamping force.

(3) In particular, the lower gripping piece constituting the clamping device has a rising position protruding above the upper surface of the table, a lowering position lower than the upper surface, and a holding position in contact with the lower surface of the workpiece. When the lower holding piece is in the raised position, the workpiece on the table is advanced and the front surface of the workpiece is brought into contact with the lower holding piece. Positioning on the front side can be performed. That is, the lower gripping piece can be used for positioning the workpiece.

(4) If the front edge of the table facing the lower gripping piece is configured as a straight edge extending in the left-right direction, even if the workpiece is close to the diameter of the table, the table The workpiece placed on the straight edge (front edge) can be projected from the straight edge.
As a result, the overhanging portion can be clamped by the upper and lower gripping pieces, and machining can be performed on the work portion that forms the front side of the gripped portion, so that the range in terms of the size of the workpiece can be further expanded. .

1 is a perspective view showing a machine tool according to the present invention. It is the side view. It is a front view which shows the structure of an up-and-down holding piece. It is sectional drawing explaining the structure of the guide of the both sides of the upper clamping piece. It is a perspective view which shows a workpiece | work. It is a front view explaining the structure which moves a table to the front-back direction. It is a front view explaining the structure of a table and the structure of an indexing device. It is a perspective view which shows the structure of a table, and the structure of an indexing apparatus with a movable stand and a workpiece | work fall prevention plate. It is a perspective view which shows the state which united the three. It is a top view which shows the table side of a machine tool. It is a front view which shows the table side of a machine tool. It is a fragmentary perspective view explaining the structure of the upper clamping piece. It is explanatory drawing which shows the structure which fixed the cushion material to the notch recessed part provided in the clamping surface of the upper clamping piece with the effect | action of this cushion material. It is a perspective view which shows the state which the upper and lower clamping pieces clamped the workpiece | work. It is a perspective view explaining the structure which moves a lower holding piece up and down. It is a side view which shows the raising position of a lower clamping piece. It is a side view which shows the downward position of a lower clamping piece. It is a side view which shows the state which the table moved forward with the lower holding piece in the lowered position. It is a side view which shows the state which the upper and lower clamping pieces clamped the workpiece | work. It is a top view which shows the positioning state of the workpiece | work in the machine tool which concerns on this invention. It is a side view which shows the state where the upper and lower holding pieces hold the work and the upper and lower milling cutters are chamfered. It is a front view which shows the movement state in the left-right direction of the moving frame provided with an upper and lower milling cutter. It is a side view of a moving frame. It is sectional drawing explaining the structure of the movement of the left-right direction of a moving frame. It is sectional drawing explaining the structure of the up-and-down movement of an upper milling machine. It is the top view and side view explaining the process of measuring a workpiece | work using a contact-type measuring device. It is a top view explaining the process of measuring a workpiece | work using a non-contact type measuring apparatus. It is the top view and sectional drawing explaining the one aspect | mode of the advantage of the table by which the front edge part was comprised as a linear edge part. It is the top view and sectional drawing explaining the other aspect of the advantage of the table by which the front edge part was comprised as a linear edge part. It is a disassembled perspective view which shows the lower clamping piece which has a notch opening part. It is a perspective view which shows the state which closed the notch open part by the connection board part. It is a top view explaining the effect | action of a notch opening part.

  1 to 3, a machine tool 1 according to the present invention includes a table 3 on which a workpiece 2 is placed, and a clamp device 5 (FIGS. 3 and 21) disposed on the front side of the table 3. And a tool 6 that is disposed on the front side of the table 3 and performs machining on the workpiece 2, and the clamping device 5 is arranged in front of the table 3 with respect to the workpiece 2 placed on the table 3. Upper and lower gripping pieces 10 and 11 for gripping a projecting portion 9 projecting from the edge portion 7 from above and below are provided. Then, as shown in FIG. 21, the tool 6 forms the front side of the clamped portion 12 of the workpiece 2 with the upper and lower clamping pieces 10, 11 clamped on the projecting portion 9. The machined portion 13 is machined.

  As shown in FIG. 5, the workpiece 2 has a rectangular parallelepiped shape, and the length of one side is set to, for example, 150 to 500 mm in a plan view. In FIG. 5, it is formed in a square having a side length of 300 mm in plan view.

  As shown in FIG. 6, the upper surface 15 of the table 3 is horizontal, and can be rotated about the vertical axis by the indexing device 16 and moved in the front-rear direction F1 by the linear motion device 17 (FIG. 1). it can.

  As shown in FIGS. 2 and 6 to 9, the indexing device 16 divides the outer periphery of the work 2 placed on the upper surface 15 of the table 3 at a required angle in the circumferential direction. A specific configuration of the indexing device 16 will be described with reference to FIGS. 6 to 9. A support cylinder body is provided in a support hole 20 penetrating in a vertical direction at a central portion on the front side of a movable base 19 having a rectangular plate shape. 21 is inserted, and the flange portion 22 is placed on the peripheral portion 23 of the support hole 20 with the flange portion 22 provided around the upper end side of the support cylinder 21. Are fixed by bolts 25. In this embodiment, the front edge portion 26 of the flange portion 22 is formed as a trapezoidal edge portion protruding forward, and the length L1 of the linear base end edge portion 27 is set to 132 mm, for example. Yes.

  As shown in FIGS. 6 to 7, a drive shaft 30 is inserted into the circular insertion hole 29 provided along the axis of the support cylindrical body 21 with the common axis, and the upper end of the drive shaft 30 is The portion 31 is bolted to the lower portion 32 of the table 3. The upper end portion of the support cylinder 21 is continuously provided with a notch recess 33 concentrically with the axis of the support cylinder 21 in the circumferential direction. A lower ring member 37 of a thrust ball bearing 36 concentric with the notched recess 33 is placed, and the upper surface 40 of the upper ring member 39 supports the lower surface 41 of the table 3 from below. As a result, the table 3 is rotatable about the axis of the drive shaft 30. The drive shaft 30 is supported by a radial ball bearing 42, a thrust ball bearing 43, and a radial ball bearing 45 from the top to the bottom at a required interval when viewed in the vertical direction, and is rotatable about the axis. ing. Further, a motor output shaft 49 protruding upward from a control motor 47 such as a servo motor or a stepping motor capable of accurately controlling the rotation angle is connected to the lower end portion 46 of the drive shaft 30 via a speed reducer 50. As shown in FIG. 7, the axis L2 of the table 3, the axis L3 of the drive shaft 30, and the axis L4 of the motor output shaft 49 are vertically aligned with each other. Further, in order to prevent the table 3 from rotating while the tool 6 is processing the workpiece 2, a brake device 51 is provided between the lower end portion 46 of the drive shaft 30 and the speed reducer 50. Is provided.

  As shown in FIGS. 1-2, 6, and 10-11, the linear motion device 17 reciprocates the table 3 in the front-rear direction F1 by enabling the movable base 19 to reciprocate in the front-rear direction F1. Sliding members 52, 52 are provided on the lower surface portions of both side portions of the movable base 19 in the left-right direction F2. The sliding members 52, 52 are fixed to the upper ends 56, 56 of the left and right support standing walls 55, 55 that are erected in the front / rear direction support base 53, and extend in the front / rear direction F1. It is guided by 57 and can be reciprocated in the front-rear direction. A screw cylinder member 59 is fixed to the lower surface 54 of the movable base 19 as shown in FIG. 11, and the screw cylinder member 59 extends in the extending direction of the guide rails 57 and 57 as shown in FIG. Further, both sides are screwed into a drive screw shaft 60 supported by bearings 58a and 58b. As shown in FIG. 11, the rear end portion 61 of the drive screw shaft 60 and the motor output shaft 63 of a control motor 62 such as a servo motor or a stepping motor disposed below the rear end portion 61 are The gears 64 and 68 and the timing belt 74 are connected. However, when the drive screw shaft 60 is rotated forward by the electric motor 62, the movable table 19 can be moved forward, and when the drive screw shaft 60 is rotated reversely, the movable table 19 can be moved backward.

  In the present embodiment, the table 3 has a square shape in plan view as shown in FIG. 8, and straight edges 65, 65, 65 and 65 are formed at an angle of 90 degrees, and the adjacent linear edge portions 65 and 65 are formed in an arc shape. Accordingly, the front edge 7 of the table 3 facing the lower gripping piece 11 is formed as a straight edge 65. In this embodiment, as shown in FIG. 8, shallow recesses 66, 66 are provided in front of and behind the upper surface 15 of the table 3, and a vent hole 69 is formed in the bottom portion 67 of the recess 66 in the vertical direction. Is provided. The upper end of the vent hole 69 opens at the upper surface of the bottom portion 67 and the lower end thereof is connected to an air suction / blow-out device (not shown) that sucks or blows air. The distance between the opposing linear edge portions 65, 65 of the table 3 is set to 132 mm, for example. As shown in FIGS. 1 and 9 to 10, the table 3 surrounds the left and right side portions 3 b and 3 c except the front side portion 3 a and the rear side portion 3 d and substantially follows the side surface 73 of the flange portion 22. In this state, a work drop prevention plate 75 surrounding the table 3 is provided. As shown in FIGS. 8 to 9, the workpiece fall prevention plate 75 is provided so as to be lifted from the movable table 19 by four columns 78. The workpiece fall prevention plate 75 provided in this way supports the workpiece from below and prevents the workpiece 2 from falling when the workpiece 2 placed on the table 3 loses balance and comes off the table 3. .

  As shown in FIGS. 3, 12 to 14, and 21, the upper gripping piece 10 can be moved up and down by an upper lifting device 76, pressing the overhanging portion 9 of the work 2 to contact the lower gripping piece 11. The overhanging portion 9 is held between them, and the lower surface thereof is a straight upper holding surface 77 extending in the left-right direction.

  As shown in FIGS. 1 and 3, the upper lifting device 76 includes a cylinder 79 that can expand and contract in the vertical direction. The cylinder 79 includes a lateral column 44 formed by connecting upper ends 38 of the column members 34, 34 standing on both sides of the front portion of the front / rear direction support base 53 with a horizontal member 44. It is erected at the central portion in the length direction of the frame member 44. As shown in FIG. 12, the lower end portion 81 of the piston rod 80 of the cylinder 79 is connected to the central portion in the length direction of the upper end portion 84 of the upper gripping piece 10 via a joint 82. Further, the sliding members 83 and 83 provided at both left and right end portions of the holding piece 10 on the upper side extend in the vertical direction to the inner portions of the support members 34 and 34 as shown in FIGS. It is guided by guide rails 85, 85 provided as described above, and can reciprocate in the vertical direction F3.

  However, as the piston rod 80 descends and the cylinder 79 extends, the left and right sliding members 83 and 83 are guided by the left and right guide rails 85 and 85 as shown by arrows in FIG. As shown in FIG. 14, the upper holding surface 77 as the lower surface of the upper holding piece 10 presses the protruding portion 9 downward. Further, as the piston rod 80 is raised and the cylinder 79 is contracted, the left and right sliding members 83 and 83 are guided by the left and right guide rails 85 and 85 and can be raised in a stable state.

  In this embodiment, as shown in FIG. 13A, notch recesses 86 are provided at equal intervals on the holding surface 77, and a cushion material 87 made of a rubber elastic material is fixed to the notch recesses 86. The lower surface 89 of the cushion material 87 is configured to protrude downward from the holding surface 77 in the free state. However, when the upper gripping piece 10 is lowered and the upper gripping surface 77 presses the overhanging portion 9, first, the lower surface 89 of the cushion material 87 abuts on the upper surface 90 of the overhanging portion 9, Thereafter, as shown in FIG. 13B, the cushion material 87 is elastically compressed, and the upper gripping surface 77 presses the upper surface 90. Therefore, in this embodiment, the pressing of the upper holding surface 77 against the upper surface 90 of the overhanging portion 9 is quietly performed with the elastic compression of the cushion material 87.

  On the other hand, as shown in FIGS. 1 to 3 and FIGS. 14 to 16, the lower holding piece 11 is a central portion 92 in the length direction of the substrate portion 91 extending in the left-right direction F <b> 2 in the present embodiment. Lower end portions 96, 96 of the portion 95 are fixed by bolts or the like, and the upper surface thereof is a straight lower holding surface 97 extending in the left-right direction. In this embodiment, as shown in FIGS. 1, 3, and 14, the upper projecting plate portion 95 is positioned on the left and right sides of the rear surface 94, and the upper end 98 (lower gripping portion) of the upper projecting plate portion 95 is disposed. Receiving pieces 108, 108 are provided, which are located below the surface 97) and whose upper surfaces 104, 104 have the same horizontal plane. The receiving pieces 108 and 108 prevent the workpiece 2 from falling by receiving the overhanging portion 9 from below when the overhanging portion 9 is inadvertently lowered downward.

  The lower holding piece 11 having such a configuration can be moved up and down by the lower lifting device 100 shown in FIGS. 10 and 15 to 16, and ascended position 101 protruding above the upper surface 15 of the table 3 shown in FIG. The lowering position 102 lower than the upper surface 15 shown in FIGS. 17 to 18 and the holding position 105 where the lower holding surface 97 shown in FIG. 19 is in contact with the lower surface 103 of the workpiece 2 can be taken.

  In the present embodiment, as shown in FIGS. 3, 10, and 15 to 16, the lower lifting device 100 includes sliding members 123, 123 fixed to both end portions of the substrate portion 91, and the column members. Guided by guide rails 85 and 85 provided so as to extend in the vertical direction on the inner portions of 34 and 34, it can reciprocate in the vertical direction. Further, as shown in FIGS. 15 to 16, the lower ends of the connecting members 106 and 106 fixed to the both ends of the substrate 91 are rotated around the horizontal axis on the outer surfaces 107 and 107 viewed in the left-right direction. Engaging rollers 109, 109 are provided.

  The engaging rollers 109 and 109 are inserted into a restriction long hole 113 provided in the longitudinally sliding slide plate 112 that is movable in the longitudinal direction by the lower surface 110 being supported by the longitudinal support rollers 111 and 111. The upper and lower ends 126 and 127 are fitted in close contact with each other. The restriction long hole 113 is formed as a step-like long hole that is long in the front-rear direction. The lower restriction hole 115, the middle restriction hole 116 located about 4 mm above that, and the middle restriction hole 116. Furthermore, the upper stage regulation hole 117 which exists in about 5 mm upper position is provided. The lower-stage regulating hole 115 and the middle-stage regulating hole 116 are communicated with each other by a downward upward inclined hole 119, and the middle-stage regulating hole 116 and the upper-stage regulated hole 117 are communicated by an upper upward inclined hole 119. It is in a state. Further, the longitudinally engaging plate 112 having such a configuration has a rear portion 120 disposed at the rear of the longitudinally engaging plate 112 so that the joint 125 is attached to the front end of the piston rod 122 of the cylinder 121 that can expand and contract in the longitudinal direction. Are connected to each other.

  However, when the piston rod 122 moves forward and the cylinder 121 extends, the longitudinally moving engagement plate 112 is supported by the front and rear support rollers 111 and 111 and can move forward in a horizontal state. Further, when the piston rod 122 is retracted and the cylinder 121 is contracted, the longitudinally moving engagement plate 112 is supported by the front and rear support rollers 111 and 111 and can be retracted in a horizontal state.

  17 to 18 show a state in which the cylinder 121 is reduced to the minimum and the engagement roller 109 is positioned in the lower-stage restriction hole 115, and the upper and lower ends 126 and 127 of the engagement roller 109 are the lower-stage restriction hole 115. The upper and lower surfaces 129 and 130 are in close contact with each other. In this state, the lower holding piece 11 exhibits the lowered position 102 in which the lower holding surface 97 is located about 4 mm below the lower surface 103 of the workpiece 2.

  FIG. 19 shows a state in which the cylinder 121 is stretched and the engagement roller 109 is positioned in the middle stage restriction hole 116, and the upper and lower ends 126 and 127 of the engagement roller 109 are the upper and lower surfaces of the middle stage regulation hole 116. 131 and 132 are in close contact with each other. In this state, the lower holding piece 11 exhibits the holding position 105.

  FIG. 16 shows a state in which the cylinder 121 is further extended and the engagement roller 109 is positioned in the upper restriction hole 117, and the upper and lower ends 126 and 127 of the engagement roller 109 are the upper and lower surfaces of the upper restriction hole 117. 133 and 135 are in close contact. In this state, the lower holding piece 11 exhibits the raised position 101 in which the lower holding surface 97 protrudes upward by about 5 mm from the lower surface 103 of the workpiece 2.

  Then, as shown in FIG. 16, the work 2 is suspended from the upper surface 15 of the table 3 with the lower gripping piece 11 in the raised position 101, and the work 2 is advanced on the upper surface 15. The protruding portion 9 can be formed by bringing the front surface 136 into contact with the upper protruding portion 137 of the lower holding piece 11. When the workpiece 2 is moved in this manner, if the air is blown out by the air suction / blowing device, the workpiece 2 which is a heavy object can be lifted with air and moved lightly.

  In this embodiment, as shown in FIGS. 1 and 20, the clamping device 5 is positioned on one side of the workpiece 2 as viewed in the left-right direction F <b> 2 and is adjacent to the adjacent surface 139 adjacent to the front surface 136 of the workpiece 2. A positioning part 140 capable of abutting is provided. The positioning unit 140 can move back and forth in the front-rear direction F1, and the arrangement state in the left-right direction F2 uses the length (work width) of the side 141 in the left-right direction F2 before processing the workpiece 2 as a numerical control unit. Can be set by typing. For example, when the length L2 of the side 141 is 300 mm and the workpiece width is input as 300 mm, the positioning unit 140 moves the table in the left-right direction F2 in the present embodiment by moving the moving frame 143, which will be described later. 3 can be automatically placed at a position moved from the center 138 to the right by 150 mm equal to half the workpiece width (rightward in FIG. 1 and leftward in FIG. 20).

  Accordingly, in this embodiment, as shown in FIGS. 16 and 20, the front surface 136 of the workpiece 2 placed on the table 3 and the front gripping piece 11 with the lower gripping piece 11 in the raised position 101 and the By bringing the adjacent surface 139 into contact with the protruding portion 137 (FIG. 16) of the lower holding piece 11 and the positioning portion 140 in the protruding state, the horizontal direction F2 and the front-rear direction F1 of the workpiece 2 are outlined. Can be simultaneously positioned. Also, as shown in FIGS. 17 to 18, the table 3 moves forward by a required amount as shown by an arrow in FIG. As shown in FIG. 19, the gripping piece 11 is lifted so as to exhibit the gripping position 105 and the upper gripping piece 10 is lowered so that the overhanging portion 9 is gripped by the upper and lower gripping pieces 10, 11. It is made like that. In addition, when holding the overhanging portion 9 with the upper and lower holding pieces 10 and 11 in this way, as long as the overhanging portion 9 can be held in a stable state, the upper and lower holding pieces 10 and 11 are in a vertically opposed state. Not required. In FIG. 19, the position is slightly shifted due to the arrangement state of other components.

  In this embodiment, the tool 6 is configured as a milling cutter 6a that chamfers the edge portion 142 of the workpiece 2 as shown in FIGS. In the present embodiment, the milling cutter 6a is provided above and below a moving frame 143 that can move in the left-right direction F2 in order to improve the chamfering efficiency of the workpiece 2. As shown in FIG. 22, the upper milling cutter 6a1 can move in the left-right direction F2 and the up-down direction F3, and can move in the left-right direction F2 together with the moving frame 143 by moving the moving frame 143 in the left-right direction F2. Accordingly, the upper milling edge 6a1 chamfers the horizontal upper edge 142a (FIG. 5) and the vertical vertical edge 142b (FIG. 5) of the workpiece 2 as shown in FIG. Can be applied. On the other hand, as shown in FIG. 22, the lower milling cutter 6a2 can move in the left-right direction F2 but cannot move in the up-down direction F3 due to the movement of the moving frame 143 in the left-right direction F2. The lower horizontal edge 142c (FIG. 5) can be chamfered.

  As shown in FIG. 1, the moving frame 143 has a box shape, and is provided on a left and right direction support base 150 disposed on the front end side of the front and rear direction support base 53. Then, the lower milling cutter 6a2 is fixedly provided at the lower portion of the one side portion 145 (right side portion in FIG. 1) viewed in the left-right direction F2 of the moving frame 143 with its rotating shaft protruding rearward. ing. Further, the positioning part 140 is provided to be extendable in the front-rear direction F1 on the lower side of the lower milling cutter 6a2 (outside as viewed in the left-right direction F2).

  The means for moving the moving frame 143 in the left-right direction F2 is configured, for example, as shown in FIGS. 1 and 23 to 24, and sliding members 149, 149 provided on the front and back of the lower surface of the moving frame 143 are provided. These are guided by guide rails 151 and 151 which are arranged in parallel to the front and rear of the left and right support base 150 and extend in the left and right direction, and can reciprocate in the left and right direction F2. As shown in FIGS. 23 to 24, a screw cylinder member 153 (FIG. 24) is fixed to the lower surface 152 of the moving frame 143, and in the central portion viewed in the front-rear direction of the left-right support base 150, A drive screw shaft 155 extending in the left-right direction is disposed, and both sides of the drive screw shaft 155 are supported by bearings 156 and 156. A motor output shaft 161 of a control motor 160 such as a servo motor or a stepping motor is connected to one end portion (right end portion in FIG. 24) 157 of the drive screw shaft 155 via a joint 159. Then, when the drive screw shaft 155 is rotated forward by the control motor 160, the moving frame 143 can move to one end side position (for example, right end side position shown in FIG. 24) 162 in the left-right direction F2, and the drive By rotating the screw shaft 155 in the reverse direction, the moving frame 143 can move to the other end side position (left end side position) 163 in the left-right direction F2.

  The means for moving the upper milling cutter 6a1 in the vertical direction F3 is configured, for example, as shown in FIGS. 1, 23, and 25, and the rear surface of the moving frame 143 in the left-right direction other side portion 164. Guide rails 166 and 166 extending in the vertical direction are provided on the left and right sides of the vertical lift opening 165 (FIG. 1). Then, sliding members 169 and 169 provided on both sides of the rear surface of the lifting plate 167 supporting the upper milling cutter 6a1 are guided by the left and right guide rails 166 and 166, so that the lifting plate 167 can move up and down. Has been made.

  Further, as shown in FIGS. 23 and 25, a screw cylinder member 172 is fixed to the outer peripheral surface 171 of the protective cylinder portion 170 of the upper milling cutter 6a1, and the moving frame 143 has a vertical direction. An extending drive screw shaft 173 is supported by upper and lower bearings 174 and 175 so as to be rotatable about a vertical axis, and the screw cylinder member 172 is screwed to the drive screw shaft 173. A motor output shaft 179 of a control motor 177 such as a servo motor or a stepping motor is connected to one end portion (upper end portion in FIG. 23) 175 of the drive screw shaft 173 via a joint 176. However, when the drive screw shaft 173 is rotated forward by the control motor 177, the elevating plate 167 can move in one of the vertical directions (downward in FIG. 23), and the drive When the screw shaft 173 is rotated in the reverse direction, the elevating plate 167 can move upward.

  Next, an operation process of chamfering the workpiece 2 on the table 3 with the upper and lower milling cutters 6a1 and 6a2 using the machine tool 1 having such a configuration will be described.

  First, for example, as shown in FIG. 2, the workpiece 2 is suspended from the upper surface 15 of the table 3 in a state where the table 3 is separated from the rear of the upper and lower gripping pieces 10 and 11. The work 2 can be easily suspended because there is no obstacle on the upper side of the table 3. When the workpiece 2 suspended in this manner on the upper surface 15 of the table is positioned as described above with reference to FIGS. 16 and 20, the overhanging portion 9 is formed as shown in FIG. . Thereafter, as shown in FIG. 19, the projecting portion 9 is clamped by the upper and lower clamping pieces 10 and 11 to clamp the workpiece 2. In this embodiment, in order to improve the accuracy of chamfering, the front surface 136 of the workpiece 2 is moved in the left-right direction (the horizontal movement direction of the milling cutter 6a) using the measuring device 180 (FIG. 1) prior to the clamping. The workpiece is positioned so as to be correctly parallel to F2.

  In this embodiment, the measuring device 180 is configured as a contact-type measuring device 180a, for example. For example, as shown in FIGS. 1 and 20, the measuring instrument 180 is provided on the left end side of the moving frame 143 (the left end side in FIG. 1 and the right end side in FIG. 20). A child 183 is accommodated in the protective cylinder 184. The measuring element 183 can be moved back and forth in the front-rear direction F1 by expansion and contraction of the cylinder 144. From the most retracted state as shown by a broken line in FIG. 20, as shown by a one-dot chain line in FIG. It can be advanced (protruded) beyond the front end 181 with respect to the front surface 136 within a range of 50 mm, for example. The measuring device 180 having such a configuration can move in the left-right direction by moving the moving frame 143 in the left-right direction F2.

  Here, the work positioning process by the measuring instrument 180 will be described. FIG. 26 shows a state in which the positioning portion 140 is retracted as shown by a one-dot chain line in FIG. 25 and the lower holding piece 11 is in the lowered position 102 as shown in FIG. As shown to (A), the said measuring element 183 moves to the other end side position (for example, position of the left end side shown in FIG. 24) 163 seen in the left-right direction of the said front surface 136 of the said workpiece | work 2, and this other end At a side position (for example, a position that is 20 to 30 mm from the other end 185 and enters the inside) 163 and at a position that is 2 to 3 mm above the bottom surface 190 of the workpiece 2, for example, as shown in FIG. The probe 134 advances toward the front surface 136. The tip 186 of the probe 183 abuts on the front surface 136 as shown by the solid line on the right side of FIG. As shown in A), the first distance D1 between the front end 136 of the probe 183 in the retracted state and the front surface 136 can be measured.

  Thereafter, the measuring element 183 is retracted as indicated by a broken line in FIGS. 20 and 26, and as shown by a one-dot chain line in FIG. 26A, the one end side position (the right end shown in FIG. Side position) 162. The measuring element 183 moves forward toward the front surface 136 at the one end side position 162 (for example, a position entering the inner side of about 20 to 30 mm from the one end 189) and, for example, 2 to 3 mm above the bottom surface 190 of the workpiece 2. To do. The tip 186 of the probe 183 abuts on the front surface 136 as indicated by a one-dot chain line in FIG. 26 (A), so that a second between the tip 186 of the probe 183 in the retracted state and the front surface 136 is obtained. The distance D2 can be measured.

  In this embodiment, the contact position of the measuring element 183 with respect to the front surface 136 is set 2 to 3 mm above the bottom surface 190 of the work 2 even when the minimum thickness of the work 2 is set to 4 mm. This is because the workpiece 2 can be measured. The height from the bottom surface 190 is set only in relation to the minimum thickness of the workpiece 2, and in short, is determined by the relationship with the thickness of the workpiece to be machined by the machine tool 1.

  When the measured first distance D1 and the second distance D2 are the same, the front surface 136 is correctly parallel to the moving direction (left-right direction F2) of the measuring instrument 180. When the first distance D1 and the second distance D2 are different, the table 3 is rotated by the control motor 47 around the axis by a required amount. Thereby, the distance D1 between the tip 186 and the front surface 136 at the other end side position 163 and the distance D2 between the tip 186 and the front surface 136 at the one end side position 162 are equal. It is corrected as follows. By this correction, the front surface 136 is in a correct parallel state with the left-right direction (the horizontal movement direction of the milling cutter 6a) F2.

  After the workpiece 2 is positioned in this manner, the table 3 is advanced by a required amount (for example, about 10 to 20 mm) as shown in FIG. 18 in consideration of the size (depth) of chamfering. Thereafter, as shown in FIG. 19, the workpiece 2 is clamped by the overhanging portion 9 being held between the upper and lower holding pieces 10 and 11. In the workpiece clamp state, for example, as shown in FIG. 21, the upper and lower milling cutters 6 a 1 and 6 a 2 perform chamfering on the edge portion 142 which is the workpiece 13. In this embodiment, the upper milling cutter 6a1 can move not only in the horizontal direction but also in the vertical direction, so that it chamfers with respect to the horizontal edge 142a (FIG. 5) in the horizontal direction of the processed portion 13. In addition to being able to perform processing, chamfering processing can also be performed on the vertical edge 142b (FIG. 5) in the vertical direction. The size (depth) of chamfering when chamfering is performed on the horizontal edge 142a on the workpiece 2 by the upper milling cutter 6a1 depends on, for example, the initial setting of the vertical movement amount of the upper milling cutter 6a1. Alternatively, it can be determined by the initial setting of the amount of movement of the table 3 in the front-rear direction. Further, as shown in FIG. 21, the lower mill 6a2 can be chamfered to the lower horizontal edge 142c (FIG. 5). The size (depth) of the chamfer is, for example, the table 3 can be determined by the initial setting of the amount of movement in the front-rear direction. In addition, the magnitude | size (depth) of the chamfering of each part can also be varied.

  The present invention can also be configured as follows by changing the measuring device 180 to a non-contact photoelectric device 180b. That is, in the machine tool 1 according to the present invention, in the same manner as described above, the workpiece 2 placed on the table 3 moves forward in a state where the lower holding piece 11 exhibits the raised position 101 (FIG. 16). The projecting portion 9 is formed in the same manner as described above by bringing the front surface 136 of the work 2 into contact with the lower holding piece 11. Thereafter, the lower holding piece 11 is set to exhibit the lowered position 102 (FIG. 17). In this state, the measuring element 183 of the measuring device (photoelectric device 180b) 180 that can move in the left-right direction is shown by a solid line in FIG. As shown by, the workpiece 2 moves to the other end side position 163 of the front surface 136 seen in the left-right direction. Then, at the other end side position 163, the detection unit detects the reflected light that is irradiated with the light beam at the tip 191 of the probe 183 and reflected by the front surface 136. For example, the tip 191 and the front surface are detected in a triangular manner. A first distance D3 to 136 can be measured.

  Further, as shown by a one-dot chain line in FIG. 27, the measuring element 183 moves to one end side position 162 of the workpiece 2 as viewed in the left-right direction, and at the one end side position 162, the measuring element 183 is moved. The second distance D4 between the tip 191 and the front surface 136 can be measured in the same manner by the detection unit detecting the reflected light reflected by the front surface 136 and irradiated with the light beam at the front end 191. When the measured first distance D3 and the second distance D4 are different, the table 3 is rotated by a required amount around the axis, so that the tip 191 at the other end side position 163 and the tip 191 are Correction is performed so that the distance between the front surface 136 and the distance between the tip 191 and the front surface 136 at the one end side position 162 are equal.

  Thereafter, in the same manner as described above, the table 3 is advanced by a required amount, and the projecting portion 9 is clamped by the upper and lower gripping pieces 10 and 11, whereby the workpiece 2 is clamped. In the workpiece clamp state, the milling cutter 6a chamfers the edge portion 142 which is the workpiece 13.

  After the upper and lower chamfering processing on one processing surface (front surface) of the workpiece 2 is finished, the holding state by the upper and lower holding pieces 10 and 11 is released. In this state, chamfering can be performed on the upper and lower edges of the new processing surface by rotating the table 3 by 90 degrees. Sequentially, 90 degrees is rotated in the same direction, and the measurement by the measuring device 180 is performed as described above. Thereafter, the correction as described above is performed as necessary, and the protruding portion 9 is held by the upper and lower holding pieces 10 and 11 in the same manner as described above, and thereafter, the front surface 136 is subjected to a required chamfering process. Thus, the required chamfering can be performed on all four surfaces. Thus, when rotating 90 degree | times, in order to improve the stability of the workpiece | work 2 at the time of rotation, this workpiece | work 2 is made into the fixed state to the table 3 by the vacuum suction | attraction by the air suction of the said air suction / blowing device. Good. In particular, when the large workpiece 2 is fixed to the table 3, it is possible to further firmly fix the table 3 by a magnetic adsorption action by a magnetic adsorption device (not shown).

  In the present embodiment, as described above, the front edge portion 7 on the side facing the lower holding piece 11 of the table 3 is formed as the linear edge portion 65 extending in the left-right direction. Even a relatively small workpiece (for example, a rectangular parallelepiped workpiece having a side length slightly larger than the distance between the opposing linear edge portions 65, 65 in a plan view) 2 The workpiece 2 placed on the upper surface 15 of the table can be overhanged from the straight edge (the front edge 7) 65, and the overhang 9 is located at a portion close to the straight edge 65. The upper and lower clamping pieces 10 and 11 can be clamped, and machining can be performed on the workpiece 13 that forms the front side of the clamped portion.

This will be described separately for the first type shown in FIG. 28 and the second type shown in FIG.
In the first type, the table 3 has the flange portion 22 in the same manner as described above, and the front edge portion 7 of the table is formed as a straight edge portion 65, and the front edge portion 7 and the flange portion are formed. The front edge part 26 of 22 exists in the same perpendicular | vertical surface, and has the structure similar to the above. For convenience of explanation, the table 3 is hatched. This is the same in FIG. 29 and FIG.

  Further, as shown in FIGS. 28A and 28B, the upper and lower gripping pieces 10 and 11 have the same configuration as described above, and are slightly displaced in the front-rear direction. In FIG. 28A, the workpiece 2 is configured as a rectangular parallelepiped workpiece having a side length set to, for example, 207 mm in plan view, and is placed on the upper surface 15 of the table 3. Yes. The front portion of the work 2 protrudes forward from the front edge portion 7 of the table 3 to form an overhang portion 9.

  In this state, as shown in FIG. 28 (B), the lower gripping surface 97 of the lower gripping piece 11 exhibits the gripping position 105 in contact with the lower surface 103 of the overhanging portion 9, and the upper gripping In the piece 10, the upper holding surface 77 is in contact with the upper surface 90 of the projecting portion 9 of the work 2, and the work 2 is held by the upper and lower holding pieces 10 and 11. Then, machining with the tool 6 is performed on the workpiece 13 that forms the front side of the portion 12 held by the upper and lower holding pieces 10, 11.

  Now, in the case shown in FIG. 28 (A), the table 3 has an arcuate edge 192 whose front edge 7 protrudes as shown in FIG. 28 (C) (that is, the table 3 is circular in plan view). Suppose that it has been changed to one that exhibits a shape). In this case, as shown in FIG. 28C, the width W1 of the overhanging portion 9 between the front end 193 of the arcuate edge 192 of the table 3 and the front edge 195 of the work 2 is reduced. End up. This makes it difficult or impossible to perform machining with the tool 6 on the workpiece 13 that forms the front portion of the portion 12 held by the upper and lower holding pieces 10 and 11. Therefore, the length of one side of the work 2 is inevitably set to be large as shown in FIG. FIG. 28D shows a case where the length of one side is set to 235 mm.

  As apparent from a comparison between FIG. 28A and FIG. 28D, it is possible to form the front edge portion 7 of the table as the straight edge portion 65 even if the workpiece has a shorter side length. This means that the workpiece 13 can be machined.

  In the case of the second type, in the case shown in FIG. 29, the upper and lower holding pieces 10 and 11 are not displaced forward and backward, and the holding surfaces 77 and 97 of the upper and lower holding pieces 10 and 11 are viewed in plan view. Shows the case of matching. FIG. 29C shows a case where the front edge 7 of the table 3 is configured as a projecting arcuate edge 192 when the upper and lower gripping pieces 10 and 11 are not displaced forward and backward. Yes.

  Also in this case, as apparent from a comparison between FIG. 29A and FIG. 29C, it is easier to form the front edge portion 7 of the table as the straight edge portion 65 with a shorter one side length. Even so, the machined portion 13 can be machined.

  The present invention is by no means limited to those shown in the above-described embodiments, and it goes without saying that various design changes can be made within the scope of the claims. One example is as follows.

(1) When the measuring device 180 is configured as a contact-type measuring device, in the embodiment, the measuring element 183 moves forward toward the front surface 136, and the tip 186 of the measuring element 183 is moved to the front surface. 136 is configured to measure the first distance D1 and the second distance D2 between the tip 186 and the front surface 136, but conversely, the probe 183 is The table 3 is moved forward with respect to the fixed measuring element 183 without being moved forward, and the tip 186 of the measuring element 183 comes into contact with the front surface 136 so that the first distance D1 and the second distance are reached. It can also comprise so that D2 can be measured. Alternatively, the advance of the measuring element 183 and the advance of the table 3 can be combined. Such a configuration is particularly preferable when the advance stroke of the probe 183 becomes too large or when the advance stroke is insufficient.

(2) As each of the cylinders 79 and 121, an air cylinder, a hydraulic cylinder, and other fluid pressure cylinders can be adopted.

(3) For machining by the machine tool according to the present invention, in addition to the chamfering described above, milling of the entire side surface of the workpiece, drilling, grooving such as vertical grooving, tapping, polishing Various machining processes that can be performed on the workpiece 13 such as machining and punching are included.

(4) When the machining is chamfering, the number of the milling cutters (tools) 6a may be two as described above, or may be only one of the movable milling cutters 6a1. . Even when the number of milling cutters 6a is one, chamfering can be performed on the upper, lower, left and right edge portions 142a and 142c on the front surface 136 of the workpiece by the moving operation of the milling cutter 6a.

(5) The table 3 may be configured to have a square shape in a plan view as well as a circular shape or other shapes in a plan view.

(6) Workpieces that can be machined by the machine tool according to the present invention are not specified as those that have a square shape in a plan view, but are polygons such as a rectangular shape, a hexagonal shape, an octagonal shape, a trapezoidal shape, and a rhombus shape in a plan view. In addition to the shape, the shape may be a combination of a curved side such as an arc and a straight side.

(7) FIGS. 30 to 32 show other modes of the lower gripping piece 11, and the straight bases of the flange portion 22 at the left and right portions 196 and 196 of the base plate portion 91 extending in the left-right direction F <b> 2. A clearance gap 197 (for example, having a width of 140 mm) for releasing the end edge portion 27 is formed, and the lower end portions 200, 200 of the left and right upper projecting plate portions 199, 199 are fixed by bolts or the like. A notch opening portion 202 (the relief gap 197) having an open upper end 201 is provided at a central portion of the holding piece 11 in the length direction. The left and right protruding plate portions 199, 199 are provided with slide grooves 205, 205 extending in the vertical direction on the facing surfaces 203, 203, respectively. The slide grooves 205 and 205 are fitted with slide ridges 209 and 209 that protrude in the vertical direction on both side surfaces 207 and 207 of the connecting plate portion 206 disposed so as to close the notch opening portion 202. The connecting plate portion 206 can be moved in the vertical direction and is detachable. FIG. 31 shows a state in which the connecting plate portion 206 closes the notch opening portion 202, and the upper surface 210 of the connecting plate portion 206 and the upper surfaces 207 and 207 of the upper protruding plate portions 199 and 199 are flush with each other. In this state, the upper surface of this flush surface forms the lower holding surface 97 of the lower holding piece 11.

  When the lower gripping piece 11 is configured to have the notch opening portion 202 that can be opened and closed in this way, a straight bottom formed by closing the notch opening portion 202 with the connecting plate portion 206. The overhanging portion 9 of the workpiece 2 can be stably held between the holding surface 97 and the upper holding surface 77 as the lower surface of the upper holding piece 10. Then, by removing the connecting plate portion 206, for example, as shown in FIG. 32, the front portion 211 of the flange portion 22 of the table 3 is fitted into the escape gap (notch opening portion 202). The table 3 is set to the forward state as much as possible. In this state, a relatively small work 2 smaller than the width of the notch opening portion 202 is placed on the upper surface 15 of the table 3, and the work 2 passes through the notch opening portion 202 as shown in FIG. When it is advanced manually, the machined portion 13 can be machined by the tool 6.

DESCRIPTION OF SYMBOLS 1 Machine tool 2 Work piece 3 Table 5 Clamping device 6 Tool 6a Milling cutter 6a1 Milling cutter 6a2 Lower milling cutter 7 Front edge portion of table 9 Overhanging portion 10 Holding piece 11 Lower holding piece 12 Holding portion 13 Worked portion 15 Upper surface of table 16 Indexing device 19 Movable base 22 Flange part 26 Front edge part of flange part 27 Base edge part 47 Control motor 62 Control motor 65 Linear edge part of table 75 Work drop prevention plate 93 Relief gap 99 Notch opening Part 101 Lower gripping position of lower gripping part 102 Lower gripping position of lower gripping part 103 Lower surface of workpiece 105 Holding position of lower gripping part 109 Engagement roller 112 Front / rear moving engagement plate 113 Restriction hole 115 Lower regulation hole 116 Middle regulation hole 117 Upper restriction hole 136 Front surface of workpiece 139 Adjacent surface 140 Positioning portion 14 Moving frame 160 controls the motor 167 lift plate 177 controls the motor 180 meter 183 measuring element 186 bottom surface of the tip 190 the work of the probe

Claims (6)

  A table on which a workpiece is placed, a clamping device disposed on the front side of the table, and a tool disposed on the front side of the table for processing the workpiece, the clamping device comprising: The upper and lower grip pieces grip the projecting portion of the work placed on the upper surface of the table by gripping the projecting portion projecting from the front edge of the table from above and below. A machine tool comprising a clamping device for clamping a projecting portion of a workpiece, wherein the tool performs machining on a workpiece portion that forms a front side of the gripped portion of the workpiece in a workpiece clamping state. The table can move in the front-rear direction, and the lower gripping piece has a raised position protruding above the upper surface of the table, a lowered position lower than the upper surface, and a clamping position in contact with the lower surface of the workpiece. It is possible,
With the lower holding piece in the raised position, the workpiece placed on the upper surface of the table is advanced to bring the front surface of the workpiece into contact with the lower holding piece, so that the overhanging portion is After the table has advanced by a required amount in a state where the lower holding piece is in the lowered position, the lower holding piece is raised so that the lower holding piece is in the holding position. 2. A machine tool comprising a clamping device for clamping a projecting portion of a workpiece according to claim 1, wherein the portion is clamped by the upper and lower clamping pieces.   2. The clamp for clamping a projecting portion of a workpiece according to claim 1, wherein a front edge portion of the table facing the lower gripping piece is formed as a linear edge portion extending in the left-right direction. Machine tool equipped with the device. The tool performs cutting on the workpiece by moving linearly in the left-right direction, and the table can rotate about the vertical axis and move in the front-rear direction,
With the lower holding piece in the raised position, the work placed on the upper surface of the table is advanced and the front surface of the work is brought into contact with the lower holding piece to form the protruding portion. After that, the lower gripping piece is set to exhibit the lowered position, and in this state, the measuring element of the measuring instrument that can move in the left-right direction is viewed in the left-right direction of the front surface of the workpiece. The probe is moved forward relative to the front surface at the one end side position, and the tip of the probe contacts the front surface so that the tip is located between the tip and the front surface. The first distance can be measured, and the measuring element moves to the other end side of the work in the left-right direction, and the measuring element is relatively moved toward the front surface at the other end side position. It moves forward, and the tip of the measuring element comes into contact with the front surface. And made is by such a second distance can be measured between the front,
If the measured first distance and the second distance are different, the table is rotated by a required amount around the axis, whereby the distance between the tip and the front surface at the one end side position; Correction is performed so that the distance between the front end and the front surface at the other end side position is equal,
Thereafter, the table is advanced by a required amount, and the projecting part is clamped by upper and lower clamping pieces so that the workpiece is clamped. In the workpiece clamping state, the tool is machined on the workpiece. A machine tool comprising a clamping device for clamping a projecting portion of a workpiece according to claim 1. The tool performs cutting on the workpiece by moving linearly in the left-right direction, and the table can rotate about the vertical axis and move in the front-rear direction,
With the lower holding piece in the raised position, the work placed on the upper surface of the table is advanced and the front surface of the work is brought into contact with the lower holding piece to form the overhanging portion. After that, the lower holding piece is set to exhibit the lowered position, and in this state, the measuring element of the measuring device that can move in the left-right direction is seen in the left-right direction of the front surface of the workpiece. The first distance between the tip and the front surface is detected by detecting the reflected light that is irradiated with light from the probe and reflected by the front surface at the one end side position. Reflective light that can be measured and the probe moves to the other end side of the workpiece in the left-right direction as viewed in the left-right direction, and is irradiated with light from the probe at the other end position and reflected by the front surface. Is detected by the detection unit, and the tip and the front surface And made is by such a second distance can be measured in,
If the measured first distance and the second distance are different, the table is rotated by a required amount around the axis, whereby the distance between the tip and the front surface at the one end side position; Correction is performed so that the distance between the front end and the front surface at the other end side position is equal,
Thereafter, the table is advanced by a required amount, and the projecting part is clamped by upper and lower clamping pieces so that the workpiece is clamped. In the workpiece clamping state, the tool is machined on the workpiece. A machine tool comprising a clamping device for clamping a projecting portion of a workpiece according to claim 1.   A positioning portion that is positioned on one side portion of the clamping device viewed in the left-right direction and that can contact an adjacent surface adjacent to the front surface is provided, and the lower gripping piece exhibits the raised position Then, the workpiece placed on the table is positioned in the left-right direction and the front-rear direction by bringing the front surface of the workpiece into contact with the lower gripping piece and bringing the adjacent surface into contact with the positioning portion. A machine tool comprising a clamping device for clamping a projecting portion of a workpiece according to any one of claims 1 to 5, wherein the workpiece is clamped.

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