Machining tank lifting device for electric discharge machine

Abstract

This machining tank lifting device of an electric discharge machine lifts a machining tank (4) in which a machining liquid is stored. The machining tank lifting device of the electric discharge machine includes: a drive source (1) and a rack pinion (2) for lifting the machining tank (4) on the depth side of the machining tank (4); and a cylinder (5), having the function of preventing the front side of the machining tank (4) from dropping down in relation to the depth side, on the front side of the machining tank (4).

Description

EDM machine processing tank lifting device

[0001] The present disclosure relates to a machining tank lifting device for an electric discharge machine.

[0002] In electrical discharge machining, the workpiece is machined while immersed in machining fluid. If the machining fluid level drops during machining, it could lead to a fire if the fluid is oil, so from a safety perspective, the fluid level must always be kept at a constant height relative to the workpiece. A surface plate to secure the workpiece is installed inside the machining tank that stores the machining fluid, and the front and sides of the machining tank are designed to automatically rise and fall to allow for easy loading and unloading of workpieces and access to the workpieces placed on the surface plate.

[0003] In Patent Document 1, from the viewpoint of accessibility to the workpiece, a lifting mechanism for the machining tank, including a motor, rack and pinion, etc., is disposed behind the machining tank.

[0004] Japanese Utility Model Application Laid-Open Publication No. 04-038321

[0005] As described in Patent Document 1, the method of arranging the lifting mechanism for the machining tank at the rear side of the machining tank is effective for small machining tanks, but for large machining tanks exceeding approximately 100 kgf, the front side of the machining tank overhangs the rear side of the machining tank to a large extent, resulting in the problem that the front side of the machining tank sags and it becomes impossible to maintain a constant liquid level in the machining tank relative to the workpiece.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a machining tank lifting device for an electric discharge machine that can prevent sagging on the front side of the machining tank without impairing access to the workpiece, and can maintain the liquid level in the machining tank at a constant height relative to the workpiece.

[0007] In order to solve the above-mentioned problems and achieve the object, the machining tank lifting device of the present disclosure lifts and lowers a machining tank that stores machining fluid. The machining tank lifting device for an electric discharge machine is characterized in that a drive source and lifting mechanism for lifting and lowering the machining tank are disposed at the rear side of the machining tank, and a cylinder is disposed at the front side of the machining tank that has the function of preventing the front side of the machining tank from sagging relative to the rear side.

[0008] The machining tank lifting device for the electric discharge machining machine disclosed herein has the effect of preventing sagging on the front side of the machining tank without impairing access to the workpiece, and maintaining the liquid level in the machining tank at a constant height relative to the workpiece.

[0009] FIG. 1 is a side view showing a conceptual configuration of a machining tank lifting device for an electric discharge machine according to a first embodiment; FIG. 2 is a top view showing a conceptual configuration of a machining tank lifting device for an electric discharge machine according to a first embodiment; FIG. 3 is a diagram showing a configuration of an air pressure circuit that drives a cylinder of a machining tank lifting device for an electric discharge machine according to a second embodiment;

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A machining tank lifting device for an electric discharge machine according to an embodiment will be described in detail below with reference to the accompanying drawings.

[0011] First Embodiment. Fig. 1 is a side view showing the conceptual configuration of a machining tank lifting device for an electric discharge machine according to a first embodiment. Fig. 2 is a top view showing the conceptual configuration of a machining tank lifting device for an electric discharge machine according to a first embodiment. The electric discharge machine is a wire electric discharge machine or a die-sinking electric discharge machine, and the configuration of the electric discharge machining unit including the machining electrode and the like is not shown. In Fig. 1, the left side is the front side (front side) of the machining tank, and the right side is the rear side of the machining tank.

[0012] As shown in Figures 1 and 2, the machining tank lifting device includes a machining tank 4 with a base plate 6 installed on its bottom, a rack and pinion 2 as a rotary-to-linear motion conversion mechanism, a drive source 1, a fixture 3, and a cylinder 5 that performs linear motion. The drive source 1 is, for example, a motor. Electrical discharge machining is performed on a workpiece (not shown) on the base plate 6. The rack of the rack and pinion 2 is fixed to the fixture 3. The fixture 3 supports and fixes the machining tank 4. When the motor serving as the drive source 1 rotates, the pinion of the rack and pinion 2 rotates, and the rack moves up and down as the pinion rotates, as shown by arrow A. The movement of the rack moves the machining tank 4 up and down. Machining fluid is supplied to the machining tank 4 from the rear side, as shown by arrow B. The cylinder 5 is, for example, an air cylinder. A hydraulic cylinder may also be used as the cylinder 5.

[0013] The tip of the rod 5a of the cylinder 5 is arranged on the bottom surface of the front side of the processing tank 4. One cylinder 5 may be arranged in the center of the front side of the processing tank 4, or multiple cylinders 5 may be arranged in the front side of the processing tank 4.

[0014] The drive source 1 and rack and pinion 2, which are the drive mechanisms for moving the processing tank 4 up and down, are located at the rear side of the processing tank 4. Also, the cylinder 5 is located on the front side of the processing tank, forward of the center of gravity of the processing tank. A small cylinder that can save space is used as the cylinder 5. The cylinder 5 does not function to raise the processing tank 4, but rather functions as a support mechanism to prevent the front side of the processing tank 4 from sagging relative to the rear side of the processing tank 4 and to keep the processing tank 4 level. For this reason, a small and inexpensive cylinder can be selected as the cylinder 5.

[0015] 2, the hatched area 7 indicates an access area to the workpiece on the surface plate 6. To load and unload the workpiece on the surface plate 6, access is ensured from the front and both sides as shown by arrows E, making it easy to load and unload the workpiece.

[0016] As described above, according to the first embodiment, the drive source 1 and rack and pinion 2, which are the drive mechanism for moving the machining tank 4 up and down, are disposed at the back of the machining tank 4, and the cylinder 5, which serves as a support mechanism for keeping the machining tank 4 horizontal, is disposed at the front of the machining tank 4, so that the machining fluid level in the machining tank 4 can always be kept at a constant height relative to the workpiece. Also, because a small air cylinder can be used, space can be secured in front and on the sides of the machining tank 4, improving access to the workpiece.

[0017] Second Embodiment Figure 3 is a diagram showing the configuration of an air pressure circuit that drives a cylinder 5 of a machining tank lifting device of an electric discharge machine according to a second embodiment. The air pressure circuit includes a relief valve 12, which is a first valve connected to an air supply source (not shown), and a pilot check valve 13. The relief valve 12 is connected to the air supply source via an air passage 15, and the relief valve 12 is connected to the pilot check valve 13 via an air passage 16. The pilot line of the pilot check valve 13 is connected to the air supply source via an air passage 17. The pilot check valve 13 is connected to the bottom side of the cylinder 5 via an air passage 18.

[0018] The pilot check valve 13 normally applies air pressure acting in the direction of path α to the bottom side of the cylinder 5, but when air pressure is applied to path γ, it causes air from the bottom side of the cylinder 5 to flow back in the direction of path β. The relief valve 12 has the function of maintaining the air pressure in the air path 16 within a certain relief pressure, and relieves air that exceeds the certain relief pressure.

[0019] The driving source 1 is connected to a control device 8 that controls the driving of the driving source 1. The control device 8 is connected to an operation screen 9.

[0020] In the first embodiment, it is possible to maintain the machining fluid level at a constant height relative to the workpiece when the machining tank 4 is raised or stopped, but if the air supply is stopped when the machining tank 4 is lowered, there is a possibility that the front side of the machining tank 4 will sag relative to the back side of the machining tank 4. Therefore, in the second embodiment, the machining tank 4 is configured to be able to be lowered while applying air pressure at the same level as when the machining tank 4 was raised.

[0021] When the processing tank 4 is raised, air pressure is applied to path α, preventing the front side of the processing tank 4 from sagging relative to the rear side by the support of the rod 5a of the cylinder 5. Specifically, when the processing tank 4 is raised or maintained at a constant height, as shown in FIG. 1, stress C from the cylinder 5 and stress D in the opposite direction to stress C due to the operation of the drive source 1 are generated on the front side of the processing tank 4. Stress C corresponds to the first stress, and stress D corresponds to the second stress. When the processing tank 4 is raised or maintained at a constant height, stress D is greater than stress C, so air pressure is not applied to the cylinder 5 in the direction of path β, air is not relieved from the relief valve 12, and the cylinder 5 is maintained in an extended state. If stress D is extremely large compared to stress C, a load will be placed on the drive source 1, so the stress difference is set to a level that does not place a load on the drive source 1.

[0022] On the other hand, when the machining tank 4 is lowered, air pressure acting in the direction of path α is applied to the bottom side of the cylinder 5 from the air supply source via the air path 15, with the same magnitude as the air pressure when the machining tank 4 is raised. As a result, stresses C and D from the cylinder 5 act on the machining tank 4, just as when the machining tank 4 is raised. However, the force from the drive source 1 and the air pressure of the air supply source are set so that stress D when the machining tank 4 is lowered is greater than stress C from the cylinder 5. At this time, the force of the drive source 1 that holds the current position is stronger than stress D, so the height of the front side and the height of the back side of the machining tank 4 are the same.

[0023] Since stress D is greater than stress C, air pressure is applied in the direction of path β via cylinder 5. Since air pressure from path γ acts on the pilot line of pilot check valve 13, air is discharged from pilot check valve 13 to path β. Here, the relief pressure of relief valve 12 is set to an air pressure corresponding to stress C. Therefore, air is discharged from relief valve 12 by an amount equal to the difference between stress D generated by drive source 1 and stress C from cylinder 5. Therefore, even when machining tank 4 is lowered, it is possible to lower machining tank 4 while air pressure is applied.

[0024] According to the second embodiment, when the machining tank 4 is lowered, the operation of the drive source 1 generates a stress C in the machining tank 4 that is greater than the stress D from the cylinder 5, and the air pressure corresponding to the difference between the generated stress C and stress D is relieved. Therefore, even when the machining tank is lowered, the front side of the machining tank 4 can be prevented from sagging relative to the back side of the machining tank 4, and the machining fluid level in the machining tank 4 can always be maintained at a constant height relative to the workpiece.

[0025] Third Embodiment. Figure 4 is a flowchart showing the operation of a machining tank lifting device for an electric discharge machine according to a third embodiment. The configuration of the machining tank lifting device for an electric discharge machine according to the third embodiment is the same as that shown in Figure 3, and therefore a redundant description will be omitted. Due to deterioration over time, dirt, and dust accumulation in the cylinder 5, the movement of the rod 5a of the cylinder 5 becomes poor when the rod 5a is retracted into the cylinder body. As a result, the operation of the cylinder 5 becomes unstable, the operation of the machining tank 4 is not completed normally, the machine may stop, or a load may be applied to the cylinder 5, potentially damaging parts of the cylinder 5.

[0026] Therefore, in the third embodiment, in order to prevent or predict damage to components of the cylinder 5, the stress applied from the cylinder 5 to the drive source 1 is detected by measuring load data applied to the drive source 1. The measured load data applied to the drive source 1 is fed back to the control device 8. When the drive source 1 is a motor, the current value generated in the motor is used as the load data. A first threshold value and a second threshold value are set in the control device 8. The second threshold value is greater than the first threshold value. When the load data exceeds the first threshold value, the control device 8 displays a warning on the operation screen 9 urging maintenance. In this state, the machine does not stop and continues to operate. Furthermore, when the load data exceeds the second threshold value, the control device 8 stops the electric discharge machine and displays a message to that effect on the operation screen 9. The operation will be described below with reference to FIG. 4.

[0027] First, an operation instruction is output from the control device 8 to the driving source 1 (step S100). This causes the driving source 1 to perform an operation (step S110), and the processing tank 4 rises and falls (step S120). The cylinder 5 also performs an extension / contraction operation (step S130). When a load is applied to the driving source 1 (step S140), the load data is fed back to the control device 8 (step S150). The control device 8 determines whether the load data is greater than a first threshold value (step S160). If the load data is equal to or less than the first threshold value (step S160: No), the procedure proceeds to step S100. If the load data is greater than the first threshold value (step S160: Yes), the control device 8 displays a warning on the operation screen 9 prompting maintenance (step S170).

[0028] Next, an operation instruction is output from the control device 8 to the driving source 1 (step S180). As a result, the driving source 1 performs an operation (step S190), and the machining tank 4 rises and falls (step S200). Furthermore, the cylinder 5 performs an extension / contraction operation (step S210). When a load is generated on the driving source 1 (step S220), the load data is fed back to the control device 8 (step S230). The control device 8 determines whether the load data is greater than a second threshold value (step S240). If the load data is equal to or less than the second threshold value (step S240: No), the procedure proceeds to step S180. If the load data is greater than the second threshold value (step S240: Yes), the control device 8 stops the electric discharge machine (step S250) and displays a message on the operation screen 9 indicating that the machine has stopped (step S260).

[0029] In this way, in the third embodiment, when the load on the drive source 1 exceeds a first threshold value, a warning urging maintenance is displayed, and when the load on the drive source 1 exceeds a second threshold value, the electric discharge machine is stopped. Therefore, damage to components of the cylinder 5 and malfunctions of the machining tank lifting device caused by damage to components of the cylinder 5 can be prevented in advance.

[0030] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, or embodiments may be combined with each other, and some of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0031] 1 Drive source, 2 Rack and pinion, 3 Fixture, 4 Machining tank, 5 Cylinder, 5a Rod, 6 Surface plate, 7 Area, 8 Control device, 9 Operation screen, 12 Relief valve, 13 Pilot check valve, 15, 16, 17, 18 Air passage.

Claims

1. A machining tank lifting device for an electric discharge machine that lifts and lowers a machining tank containing machining fluid, characterized in that a drive source and lifting mechanism for lifting and lowering the machining tank are disposed at the back side of the machining tank, and a cylinder having a function of preventing the front side of the machining tank from sagging relative to the back side is disposed at the front side of the machining tank.

2. The machining tank lifting device for an electric discharge machine according to claim 1, characterized in that the cylinder is an air cylinder, the drive source is controlled so that when the machining tank is lowered, a second stress greater than the first stress caused by the cylinder and directed in the opposite direction is generated on the front side of the machining tank, the drive source has a first valve that relieves pressure corresponding to the difference between the second stress and the first stress, and is equipped with an air circuit connected to the cylinder.

3. The machining tank lifting device for an electric discharge machine according to claim 1 or 2, characterized in that it is equipped with a control device that acquires the load on the drive source and displays a warning when the load exceeds a first threshold value.

4. The machining tank lifting device for an electric discharge machine according to claim 3, characterized in that the control device stops the electric discharge machine and displays a message that the electric discharge machine has been stopped when the load exceeds a second threshold value that is greater than the first threshold value.

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