Workpiece seating detection device

Abstract

To provide a workpiece seating detection device which does not require a master workpiece in a normal adjustment work.SOLUTION: A workpiece seating detection device 20 includes: a detection hole 55 for discharging air from a seating surface 53 of a chuck 11 for gripping a workpiece W; an air supply flow passage 22 for sending air from an air supply source 21 to the detection hole 55; a pressure control valve 24 which is provided in the air supply flow passage 22; a pressure switch 25 which is provided in the air supply flow passage on a secondary side of the pressure control valve 24; an electromagnetic change-over valve 31 which switches connection of the air supply flow passage 22 in a detection air flow passage 35 for sending the air to the detection hole 55 or an adjustment air flow passage 36 for discharging the air to the atmosphere on the secondary side of the pressure switch 25; and a variable throttle valve 32 which is provided in the adjustment air flow passage 36.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a workpiece seating detection device that detects whether a workpiece is properly seated on a chuck that grips it, and more particularly to a workpiece seating detection device that does not require a master work in normal adjustment work. [Background technology]

[0002] In machine tools such as lathes, a workpiece is fixed to the chuck of the spindle, and cutting or other processing is performed using a tool on the workpiece that is rotated. If the workpiece is not held in a state where it is in accurate contact with the seating surface of the chuck, the workpiece may be cut in excess, resulting in a decrease in the quality of the finished product. For this reason, machine tools are provided with a workpiece seating detection device that detects whether the workpiece is properly seated on the spindle chuck. However, this workpiece seating detection device requires periodic adjustment work to ensure proper seating detection, and a master workpiece has been used as an adjustment gauge for this work up to now.

[0003] The following Patent Document 1 discloses a workpiece seating detection device that improves the workability in adjustment work. The workpiece seating detection device in the document is configured so that adjustment work can be performed using a master work at a location other than the chuck. An adjustment flow path branches off from an air supply flow path that communicates with a detection hole formed on the seating surface of the chuck, and an adjustment block is provided at the tip of the adjustment flow path. The adjustment block is installed outside the main body cover, and an adjustment hole is opened on the surface, and the adjustment flow path communicates with the adjustment hole via an opening / closing valve. Therefore, during adjustment work, the opening / closing valve is opened, and the master work is pressed against the adjustment surface of the adjustment block so as to overlap the adjustment hole. The flow rate adjustment valve is adjusted while maintaining this state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2015 / 052764 Summary of the Invention [Problem to be solved by the invention]

[0005] The workpiece seating detection device shown as a conventional example improves workability in that the adjustment work is performed outside the machine, but a master work is required for each adjustment work. Therefore, the worker must hold the master work in one hand and keep it pressed against the adjustment block, which determines the worker's standing position. The machine tool must configure the workpiece seating detection device taking into account the worker's standing position. In addition, if there is a subtle difference in the way the master work is pressed against the adjustment block by the worker, there is a risk that the adjustment results will also differ. Furthermore, the conventional workpiece seating detection device requires the storage and management of the master work, and it is necessary to take it in and out every time work is performed.

[0006] Therefore, in order to solve the above problem, an object of the present invention is to provide a workpiece seating detection device that does not require a master work for normal adjustment work. [Means for solving the problem]

[0007] The workpiece seating detection device of the present invention has a detection hole for releasing air from the seating surface of a chuck that grips a workpiece, an air supply flow path for sending air from an air supply source to the detection hole, a pressure control valve provided in the air supply flow path, a pressure switch provided in the air supply flow path on the secondary side of the pressure control valve, an electromagnetic switching valve on the secondary side of the pressure switch for switching the connection of the air supply flow path to a detection air flow path that sends air to the detection hole or an adjustment air flow path that releases air to the atmosphere, and a variable throttle valve provided in the adjustment air flow path. Effect of the Invention

[0008] According to the workpiece seating detection device having the above-mentioned configuration, air from the air supply source passes through the air supply passage and is discharged from the detection hole, and a detection signal is sent by the pressure switch based on the back pressure when the workpiece is placed on the seating surface of the chuck. Then, according to the workpiece seating detection device, after adjustment with the master workpiece placed on the seating surface, the electromagnetic switching valve is operated to switch the air supply passage from the detection air passage to the adjustment air passage, and the throttle opening of the variable throttle valve is adjusted, whereby normal adjustment work can be performed thereafter by simply switching the electromagnetic switching valve without using the master workpiece. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a side view showing the internal structure of a machine tool equipped with a workpiece seating detection device. [Diagram 2] FIG. 2 is a perspective view showing a spindle chuck. [Diagram 3] 1 is a simplified configuration diagram showing an embodiment of a workpiece seating detection device; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of a workpiece seating detection device according to the present invention will be described below with reference to the drawings. Fig. 1 is a side view showing the internal structure of a machine tool equipped with a workpiece seating detection device of this embodiment. The machine tool 1 is attached to a movable bed 3 that is movable on a base 2. A spindle unit 5 is mounted on the movable bed 3, and a spindle chuck 11 in which the workpiece seating detection device is configured is provided.

[0011] Machine tool 1 is a two-axis lathe having a turret device 6 capable of rotating and indexing a tool, a Z-axis drive device 7 for moving the tool in the front-to-rear direction of the machine body parallel to the main shaft, and an X-axis drive device 8 for moving the tool in the up-to-down direction of the machine body perpendicular to the main shaft. Machine tool 1 is equipped with a control device 9 on the rear side of the machine body, and is automatically controlled according to machining programs for various types of machining, the type of workpiece, and workpiece machining information related to tools and jigs.

[0012] The machine tool 1 is covered by a machine body cover 12 that constitutes a machining chamber 10, and furthermore, an openable front cover 13 is provided on the front part of the machine body. The machine tool 1 is modularized together with other working machines, and when a plurality of working machines are arranged in the width direction, a transfer space 15 is formed by the front cover 13. An automatic work transfer machine (not shown) that transfers the workpiece W is incorporated in the transfer space 15.

[0013] In the machine tool 1, the spindle chuck 11 in which the work seating detection device is configured is located at the back of the machining chamber 10. The adjustment work of the work seating detection device requires pressing a master work against the spindle chuck 11, which places a large burden on the worker. Therefore, it is possible to apply, for example, the above-mentioned conventional work seating detection device to the machine tool 1 of this embodiment. To do so, for example, an adjustment block for indirectly performing the adjustment work would be placed in front of the machine body. If such a conventional configuration could be realized, the worker would be able to adjust the work seating detection device outside the machine body.

[0014] However, the conventional workpiece seating detection device requires a changeover valve to be provided in the air supply flow passage connected to the spindle chuck 11, and must extend to the front part of the front cover 13 which opens and closes the adjustment air flow passage branched off from the air supply flow passage. Therefore, the conventional workpiece seating detection device is not suitable for a machine tool 1 in which the position where the spindle chuck 11 inside the machine and the adjustment block outside the machine should be located are far apart. The workpiece gripping detection device of this embodiment is configured with attention paid to these points.

[0015] 2 is a perspective view showing the spindle chuck 11 of the machine tool 1. The spindle chuck 11 is arranged at three locations at intervals of 120°, and the chuck jaws 51 are movable in the radial direction, and a stopper 52 with which the workpiece comes into contact is provided at the center. The stopper 52 is configured so that a detection hole 55 with a diameter of about 1 mm is opened in an annular seating surface 53, from which air is blown out. The detection hole 11 is formed at three locations at intervals of 120° with respect to the seating surface 53 so as to match the positions of the chuck jaws 51. When the spindle chuck 11 grips the workpiece W, the workpiece W comes into contact with the seating surface 53, and the opening of the detection hole 55 is blocked to a certain extent.

[0016] 3 is a simplified diagram showing the configuration of a workpiece seating detection device provided in machine tool 1. In this workpiece seating detection device 20, air is supplied to a detection hole 55 from an air supply source 21 such as a compressor. An air supply flow path 22 that supplies air to the detection hole 55 of the spindle chuck 11 is connected to the air supply source 21. An electromagnetic opening / closing valve 23, a pressure control valve 24, and a pressure switch 25 are connected to the air supply flow path 22 toward the spindle chuck 11 in this order. Pressure gauges 26, 27 are provided on the pressure control valve 24 and the pressure switch 25, respectively. The pressure switch 25 transmits an ON signal when the back pressure is higher than a set value, and transmits an OFF signal when the back pressure is lower than a set value.

[0017] Furthermore, the workpiece seating detection device 20 is provided with an electromagnetic switching valve 31 between the pressure switch 25 and the detection hole 55. The electromagnetic switching valve 31 has a primary side port connected to the air supply flow path 22, and two secondary side ports connected to a detection air flow path 35 connected to the three detection holes 55 and an adjustment air flow path 36 that releases air into the atmosphere as a branch flow path. The adjustment air flow path 36 is provided with a variable throttle valve 32. The electromagnetic switching valve 31 is configured so that the air supply flow path 22 is connected to the detection air flow path 35 under normal conditions.

[0018] When adjusting the workpiece seating detection device 20, the electromagnetic switching valve 31 is switched, and the air supply passage 22 is connected to the adjustment air passage 36. An operation display device 16 that displays work information and an operation screen and allows the operator to input settings is provided on the front of the machine tool 1 and is connected to the control device 9. A switching button for the electromagnetic switching valve 31, i.e., a switching button for switching the connection of the air supply passage 22 between the detection air passage 35 and the adjustment air passage 36, is provided on the operation display device 16.

[0019] In the workpiece seating detection device 20, the pressure switch 25 is first set using the master work 60. The disk-shaped master work 60 has a contact surface 61 that is brought into contact with the seating surface 53 of the spindle chuck 11 and is a polished surface with high flatness. Two adjustment grooves 63, 65 are formed in the contact surface 61 at positions shifted by 180°. By overlapping the adjustment grooves 63, 65 with the detection holes 55, it is possible to virtually create a gap that occurs between the seating surface 51 and the workpiece during machining. When adjusting the workpiece seating detection device 20, the adjustment groove 43 or 45 is overlapped with one of the three detection holes 55, and the other two detection holes 55 are blocked by the contact surface 41.

[0020] In the master work 40, one adjustment groove 63 has a depth of 0.03 mm, and the other adjustment groove 45 has a depth of 0.05 mm. The gap of 0.03 mm creates a proper seating state of the work, and the gap of 0.05 mm creates an improper seating state. The worker places the master work 40 on the seating surface 51 so that the adjustment groove 43 overlaps one of the detection holes 55, and in that state, the master work 40 is gripped by the spindle chuck 11. Then, air is released from the corresponding detection hole 55 according to the gap of 0.03 mm or 0.05 mm, and the back pressure in the air supply passage 22 increases. For back pressure adjustment, the pressure control valve 24 is operated so that the pressure switch 25 is in the ON state when the adjustment groove 63 is selected, and in the OFF state when the adjustment groove 65 is selected.

[0021] Specifically, in the case of the 0.03 mm adjustment groove 63, the back pressure is adjusted to the first set value within a predetermined time while checking the pressure gauge 27, and the pressure switch 25 is set to the ON state. If the air pressure supplied to the air supply flow path 22 is too high at this time, the switch may switch to the ON state even if a gap of 0.05 mm occurs. Therefore, the 0.05 mm adjustment groove 65 is then overlapped with the detection hole 55, and the pressure control valve 24 is adjusted while checking the pressure gauge 27, so that the back pressure becomes the second set value, which is lower than the first set value and at which the pressure switch 25 remains in the OFF state.

[0022] However, the back pressure adjustment needs to be performed many times at a predetermined time interval. This is because repeated machining by the machine tool 1 will prevent proper seating detection. For example, when the spindle chuck 11 grips the workpiece W, a machining defect may occur in the machined product even though no chips are caught in the workpiece. This is because the back pressure increases for some reason, and the pressure switch 25 turns ON and the workpiece is determined to be in a proper seating state even though a gap of 0.05 mm or more actually occurs. Therefore, the back pressure is repeatedly readjusted in the workpiece seating detection device 20.

[0023] Therefore, in the workpiece seating detection device 20 of this embodiment, after the initial adjustment using the master work 40 described above, the variable throttle valve 32 is set in preparation for readjustment of the back pressure. This is because the flow rate of air released to the atmosphere through the adjustment air flow path 36 is adjusted by adjusting the throttle opening of the variable throttle valve 32. In particular, the throttle opening of the variable throttle valve 32 is adjusted while checking the pressure gauge 27 so that the back pressure becomes the same as when the adjustment groove 65 of the master work 40 is overlapped with the detection hole 55.

[0024] Therefore, in the workpiece seating detection device 20 in which the variable throttle valve 32 has been adjusted, the electromagnetic switching valve 31 is switched and the air supply passage 22 is connected to the adjustment air passage 36, whereby a state in which the master workpiece 40 is gripped by the spindle chuck 11 and the adjustment groove 65 of 0.05 mm is overlapped with the exit hole 52 is artificially created.

[0025] Therefore, when readjustment of the back pressure in the workpiece seating detection device 20 is required, the operator presses the switch button on the operation display device 16 to operate the electromagnetic switching valve 31, and the connection of the air supply flow path 22 is switched from the detection air flow path 35 to the adjustment air flow path 36. Therefore, depending on the throttle opening of the variable throttle valve 32, a state similar to that in which the 0.05 mm adjustment groove 65 overlaps the detection hole 55 is created in the air supply flow path 22. Then, when the pressure switch 25 is turned ON, the back pressure is adjusted by operating the pressure control valve 24 so that the pressure switch 25 is turned OFF.

[0026] According to the workpiece seating detection device 20 of this embodiment, by simply pressing the switch button when readjusting the back pressure, it is possible to create a back pressure state similar to that when a master workpiece is used. Therefore, when performing normal adjustment work, the worker does not need to handle the master workpiece 40, etc., and the work becomes easier to perform. In addition, the workpiece seating detection device 20 can obtain the above-mentioned effects by simply improving the conventional configuration by providing an electromagnetic switching valve 31 and providing a variable throttle valve 32 in the adjustment air flow path 36, which is a branch flow path. The position of the variable throttle valve 32 is not particularly limited, and the workpiece seating detection device 20 can be applied to machine tools of any structure.

[0027] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above embodiment, the machine tool 1 has been taken as an example for explanation, but the machine tool may be incorporated in a machine tool of a different structure. [Explanation of symbols]

[0028] 1...machine tool 5...spindle device 9...control device 11...shaft chuck 51...chuck jaws 52...contact metal 53...seating surface 55...detection hole 20...workpiece seating detection device 21...air supply source 23...electromagnetic on-off valve 24...pressure control valve 25...pressure switch 26, 27...pressure gauge 31...electromagnetic switching valve 32...variable throttle valve 35...detection air flow path 36...adjustment air flow path

Claims

1. A detection hole for releasing air from the seating surface of the chuck that grips the workpiece; an air supply flow path for sending air from an air supply source to the detection hole; a pressure control valve provided in the air supply flow path; a pressure switch provided in the air supply flow path on the secondary side of the pressure control valve; an electromagnetic switching valve that switches the connection of the air supply flow path to a detection air flow path that supplies air to the detection hole or to an adjustment air flow path that releases air to the atmosphere, on a secondary side of the pressure switch; a variable throttle valve provided in the adjustment air flow path; A workpiece seating detection device having the same.

2. 2. The workpiece seating detection device according to claim 1, wherein the electromagnetic switching valve is switched by operating a switching button.

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