Rotating device with hydraulic mechanism

Abstract

This rotary device with a hydraulic mechanism is for reducing surge pressure in a hydraulic cylinder, and includes: a rotary mechanism that rotates a cylindrical rotary body through a drive motor; a hydraulic mechanism that provides an axial direction output through the hydraulic cylinder to an operating means via a draw bar that passes through the center of the rotary body; and a hydraulic circuit that supplies hydraulic oil delivered from a pump, lowered to a set pressure by a pressure-reducing valve, to the hydraulic cylinder, and returns the hydraulic oil discharged from the hydraulic cylinder to a tank, the hydraulic circuit being provided with an accumulator and a side branch hose, which are provided in order in the flow direction of the hydraulic oil and in a flow path connected to the hydraulic cylinder.

Description

Technical Field

[0001] The present invention relates to a rotating device with a hydraulic mechanism including a hydraulic circuit for reducing surge pressure.

Background Art

[0002] In a device using a hydraulic cylinder, it is necessary to prevent the influence of surge pressure, and a conventional example of a machine tool for that purpose is also disclosed in Patent Document 1 below. In the machine tool, a spindle head is connected to a hydraulic cylinder attached to the upper part of a column, and the spindle head can be moved up and down by supplying and discharging hydraulic oil to the hydraulic cylinder. An accumulator is connected between a pressure reducing valve in the middle and the hydraulic cylinder in a flow path connecting a hydraulic pump and the hydraulic cylinder. When the downward movement of the spindle head is switched, the hydraulic oil in the hydraulic cylinder is pressurized by a piston and temporarily rises rapidly. At that time, the hydraulic oil flows into the accumulator, and shock absorption that alleviates the rapid rise in the hydraulic cylinder is performed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There are various devices with a hydraulic mechanism using a hydraulic cylinder, and it has been an issue to mitigate the impact associated with the pressure change. In this regard, in the conventional example having a similar issue, an accumulator is provided in the hydraulic circuit, thereby mitigating the impact associated with the change in hydraulic pressure. However, the effect by the accumulator may not be sufficient depending on the device. That is, in the conventional example, the hydraulic cylinder is directly attached to the column, but in a rotating device with a hydraulic mechanism such as a tool spindle device, the hydraulic cylinder is integrally configured at a position close to other components. Therefore, in the rotating device with a hydraulic mechanism, the surge pressure generated in the hydraulic cylinder may have an adverse effect on components such as the components of the rotating part.

[0005] Therefore, an object of the present invention is to provide a rotating device with a hydraulic mechanism that reduces the surge pressure in the hydraulic cylinder in order to solve such problems.

Means for Solving the Problems

[0006] A rotating device with a hydraulic mechanism according to an aspect of the present invention includes a rotating mechanism that rotates a cylindrical rotating body by a drive motor, a hydraulic mechanism that gives an axial output by a hydraulic cylinder to operating means via a drawbar passing through the center of the rotating body, and a hydraulic circuit that reduces the hydraulic oil sent from a pump to a set pressure by a pressure reducing valve and supplies it to the hydraulic cylinder, and returns the hydraulic oil discharged from the hydraulic cylinder to a tank, and the hydraulic circuit is provided with an accumulator and a side branch hose in the order of the flow direction of the hydraulic oil in the flow path connected to the hydraulic cylinder.

Effects of the Invention

[0007] According to the above configuration, in addition to the rotation of the rotating body in the rotating mechanism by the drive motor, the hydraulic oil sent from the pump is reduced to the set pressure by the pressure reducing valve and supplied to the hydraulic cylinder, and an operation on the operating means is performed via a drawbar passing through the center of the rotating body. At this time, the hydraulic oil supplied to the hydraulic cylinder has its surge pressure reduced by the accumulator and the side branch hose.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] An embodiment of a rotary device with a hydraulic mechanism according to the present invention will be described below with reference to the drawings. The rotary device with a hydraulic mechanism described in this embodiment is a tool spindle device that forms part of a machine tool and performs machining on a workpiece using a mounted rotary tool. The machine tool is equipped with an ATC (Automatic Tool Changer), and the tool change operation for the tool spindle device of this embodiment is automatically performed. Fig. 1 is a cross-sectional view showing the main body of a tool spindle device which is an embodiment of such a rotary device with a hydraulic mechanism.

[0010] The main body 2 of the tool spindle has a cylindrical spindle 3, which is the main spindle, rotatably incorporated in the housing 4 by two bearings 11 and 12 at the upper and lower positions. A rotation mechanism is configured that can be rotationally controlled by a spindle motor 5 configured in the housing 4. At the tip of the spindle 3, a chuck mechanism 6, which is an operating means, is provided to enable the attachment and detachment of a tool 80 indicated by a one-dot chain line. The chuck mechanism 6, which consists of a collet chuck, is axially operated via a drawbar 7 passing through the inside of the spindle 3, thereby enabling clamping and unclamping of the tool 80.

[0011] Here, FIG. 2 is an enlarged cross-sectional view of part A (hydraulic mechanism part) surrounded by a two-dot chain line in FIG. 1. It shows a hydraulic cylinder 8 for operating the drawbar 7, particularly showing the state at the time of unclamping when the piston 16 has descended. The hydraulic cylinder 8 is formed with a cylinder part 15 configured on the rear end side (upper side in FIG. 1) of the spindle 3 integrally with the housing 4, and a piston 16 is incorporated in the cylinder part 15. A shaft coupling 17 is fixed to the center of the piston 16, and the drawbar 7 is connected via the shaft coupling 17 in a rotatable state.

[0012] The automatic exchange operation of the tool 80 with respect to the main body 2 of the tool spindle is performed by the ATC of the machine tool. At that time, the tool 80 is inserted into the attachment part 301 configured at the tip of the spindle 3, and the tool holder 801 is clamped by the chuck mechanism 6 that pulls it upward in the drawing. Then, rotation is applied to the spindle 3 by the drive control of the spindle motor 5, and the clamped tool holder 801 and the tool 80 rotate, and drilling and other operations are performed on the workpiece. The piston 16 is rotationally locked by a set pin 18, and the rotation between the piston 16 and the spindle 3 is blocked by the shaft coupling 17.

[0013] After the work is completed by the tool 80, the tool 80 is removed from the tool spindle main body 2 by an automatic exchange operation. The removal of the tool 80 is achieved by supplying hydraulic oil to the cylinder part 15 of the hydraulic cylinder 8, which pressurizes the piston 16 from above and displaces it downward via the draw bar 17, thereby unclamping the tool 80 in the chuck mechanism 6. Then, the tool 80 in the unclamped state of the chuck mechanism 6 is removed from the tool spindle main body 2 by the ATC.

[0014] Incidentally, it is necessary to consider the surge pressure generated in response to the operation of the hydraulic cylinder 8 in the tool spindle main body 2. The hydraulic cylinder 8 is integrally configured in the housing 4 together with the rotatably supported spindle 3, the spindle motor 5, the chuck mechanism 6 connected to the piston 16, and the like. Therefore, the surge pressure generated when the piston 16 stops in the hydraulic cylinder 8 inside the tool spindle main body 2 becomes a shock wave, also called an oil hammer, which adversely affects components such as the rotation mechanism. For example, it is conceivable that the components are deformed or displaced by the shock wave, and the rotation of the spindle 3 becomes sluggish. Therefore, the tool spindle device of the present embodiment is provided with a configuration for reducing the surge pressure.

[0015] FIG. 3 is a diagram showing a hydraulic circuit of a tool spindle device that supplies hydraulic oil to the tool spindle main body 2. In the tool spindle device 1, it is configured as a stacked valve 20 in which a pressure reducing valve 21, a direction switching valve 22, and a double pilot check valve 23 are stacked. A flow path 41 provided with a pump 31 for supplying hydraulic oil from the tank 37 to the supply flow path 32 is connected to the P port of the stacked valve 20, and a flow path 42 for returning the hydraulic oil to the tank 37 via a filter 36 is connected to the R port of the discharge flow path 35.

[0016] A pressure reducing valve 21 is provided in the supply passage 32 so that the hydraulic oil whose pressure has been reduced to the set value is supplied to the hydraulic cylinder 8. A direction switching valve 22 is connected to the supply passage 32 and the discharge passage 35 so that the connection between the clamp passage 33 and the unclamp passage 34 can be switched. A double pilot check valve 23 is connected to the clamp passage 33 and the unclamp passage 34, configured to allow the flow of the hydraulic oil supplied to the hydraulic cylinder 8 and to regulate the flow to the discharge side except when receiving the pilot pressure.

[0017] In the stacking valve 20, the A port of the unclamp passage 34 is connected to the head side of the hydraulic cylinder 8, that is, the unclamp side pressure chamber 46 of the piston 16, via the passage 43. Also, the B port of the clamp passage 33 is connected to the rod side of the hydraulic cylinder 8, that is, the clamp side pressure chamber 45 of the piston 16 to which the drawbar 7 is connected, via the passage 44. An accumulator 25 is connected to the passage 43 as a pressure reducing means in the tool spindle device 1, and a side branch hose 26 is provided. The reason for providing the pressure reducing means only in the passage 43 is that the influence of the surge pressure generated during unclamping in the tool spindle main body 2 is large.

[0018] First, during clamping in the tool spindle device 1, as described above, the chuck mechanism 6 is pulled up via the drawbar 7, and hydraulic oil is supplied to the clamp side pressure chamber 45 of the hydraulic cylinder 8. For this purpose, the hydraulic oil in the tank 37 is sent out to the passage 41 by the pump 31 and further flows to the supply passage 32 provided with the pressure reducing valve 21. At this time, the direction switching valve 22 is switched to the crank position 221, the supply passage 32 is connected to the clamp passage 33, and the unclamp passage 34 is connected to the discharge passage 35.

[0019] The double pilot check valve 23 allows the flow of hydraulic oil on the clamp flow path 33 side, and allows the flow on the discharge side by receiving the pilot pressure on the unclamp flow path 34 side. Therefore, for the hydraulic cylinder 8, the hydraulic oil flowing out from the B port of the stacked valve 20 is supplied to the clamp side pressure chamber 45, and the hydraulic oil flowing out from the opposite unclamp side pressure chamber 46 flows from the A port to the unclamp flow path 34. The hydraulic oil in the unclamp flow path 34 passes through the direction switching valve 22, flows through the flow path 42 from the discharge flow path 35, and is returned to the tank 37.

[0020] Next, during unclamping in the tool spindle device 1, as described above, the chuck mechanism 6 pushes down via the drawbar 7, so hydraulic oil is supplied to the unclamp side pressure chamber 46 of the hydraulic cylinder 8. At this time, the direction switching valve 22 is switched to the unclamp position 223, and the hydraulic oil sent from the tank 37 to the flow path 41 and the supply flow path 32 by the pump 31 flows into the unclamp flow path 34.

[0021] The double pilot check valve 23 allows the flow of hydraulic oil on the unclamp flow path 34 side, and allows the flow on the discharge side by receiving the pilot pressure on the clamp flow path 33 side. Therefore, for the hydraulic cylinder 8, the hydraulic oil flowing out from the A port of the stacked valve 20 is supplied to the unclamp side pressure chamber 46, and the hydraulic oil flowing out from the opposite clamp side pressure chamber 45 flows into the clamp flow path 33 from the B port. The hydraulic oil in the clamp flow path 33 passes through the direction switching valve 22, flows through the flow path 42 from the discharge flow path 35, and is returned to the tank 37.

[0022] Here, FIGS. 4, 5, and 6 are graphs showing the pressure changes during unclamping. In particular, FIG. 4 shows the case where no pressure reducing means is provided, FIG. 5 shows the case where only the accumulator 25 is provided, and FIG. 6 shows the case where the side branch hose 26 is used in combination with the accumulator 25. This pressure change was measured by a pressure measuring device connected to the flow path 43 immediately before the unclamp side pressure chamber 46 of the hydraulic cylinder 8. Note that the pressure reducing valve 21 provided in the supply flow path 32 is set to 2.2 Mpa.

[0023] First, when there is no accumulator 25 and side branch hose 26 as shown in Fig. 3, the pressure change was that it rapidly increased to about 2.0 Mpa at the start of the movement of piston 16 and then stabilized at 1.7 Mpa. After that, when piston 16 reached the stroke end, surge pressure S1 occurred and the value rapidly increased to 3.8 Mpa. And after the high value of surge pressure S1 continued for a certain period of time, it slowly decreased to about 1.8 Mpa and became stable. When the surge pressure S1 rises to 3.8 Mpa in this way, a large shock wave will have an adverse effect on the rotation mechanism that constitutes the tool spindle body 2.

[0024] Therefore, next, the accumulator 25 was connected to the flow path 43 as in the conventional example. The pressure change at that time was that, as shown in Fig. 4, it rapidly increased to about 2.0 Mpa at the start of the movement of piston 16 and then stabilized at 1.7 Mpa. After that, when piston 16 reached the stroke end, surge pressure S2 occurred and the value rapidly increased to 3.5 Mpa. By attaching the accumulator 25, the peak value of the surge pressure S2 decreased and the time when the surge pressure S2 occurred also became shorter. However, it was still desirable to further reduce the surge pressure in order to suppress the adverse effect on the tool spindle body 2 from the shock wave.

[0025] When the accumulator 25 was provided in the flow path 43, it was found that the surge pressure S2 generated pulsation as shown in Fig. 4. Therefore, in the tool spindle device 1 of this embodiment, a side branch hose 26 for absorbing such pulsation of the hydraulic oil was provided. That is, a side branch hose with a closed tip as a pulsation damping member is connected to the flow path 43 so as to branch between the accumulator 25 and the hydraulic cylinder 8. The side branch hose 26 is set in terms of its length, thickness, etc. so that it can absorb the pulsation of specific frequency components generated in the hydraulic circuit of the tool spindle device.

[0026] In the tool spindle device 1 in which the side branch hose 26 is used in addition to the accumulator 25 in the flow path 43, the pressure change is as shown in Fig. 5. That is, the peak pressure at the beginning of the movement of the piston 16 dropped to about 0.8 Mpa. Then, the once-dropped pressure gradually increased, and a surge pressure S3 occurred when the piston 16 reached the stroke end. The peak value at that time was 3.1 Mpa, and the time when the surge pressure S3 occurred also became shorter.

[0027] According to the tool spindle device 1 of the present embodiment, since the accumulator 25 and the side branch hose 26 are used in combination in the hydraulic circuit, the surge pressure can be effectively reduced, thereby avoiding or suppressing adverse effects on components such as the rotating structure constituting the tool spindle body 2. In particular, the effect is great in a case where a rotating mechanism including a spindle 3, a spindle motor 5, etc. and a hydraulic mechanism including a hydraulic cylinder 8, a drawbar 7, etc. are integrally configured in the housing 4 like the tool spindle device 1.

[0028] Although one embodiment of the present invention has been described, the present invention is not limited to these, and various modifications are possible without departing from the spirit thereof.

Explanation of reference numerals

[0029] 1... Tool spindle device 2... Tool spindle body 3... Spindle 4... Housing 5... Spindle motor 6... Chuck mechanism 7... Drawbar 8... Hydraulic cylinder 11, 12... Bearings 16... Piston 21... Pressure reducing valve 22... Direction switching valve 23... Double pilot check valve 25... Accumulator 26... Side branch hose 31... Pump 32... Supply flow path 33... Clamp flow path 34... Unclamp flow path 35... Discharge flow path S1, S2, S3... Surge pressure

Claims

1. A rotating mechanism for rotating a cylindrical rotating body by a drive motor, a hydraulic mechanism for applying an axial output by a hydraulic cylinder to operating means via a drawbar passing through the center of the rotating body, a hydraulic circuit that reduces the hydraulic oil sent from a pump to a set pressure by a pressure reducing valve and supplies it to the hydraulic cylinder, and returns the hydraulic oil discharged from the hydraulic cylinder to a tank, wherein an accumulator and a side branch hose are provided in order in the flow path connected to the hydraulic cylinder in the direction of the flow of the hydraulic oil, A rotating device with a hydraulic mechanism having the above components.

2. The rotating device with a hydraulic mechanism according to claim 1, wherein the rotating mechanism and the hydraulic mechanism are integrally formed within a housing.

3. The rotating mechanism is configured to rotationally control the rotating body having a rotating tool attached to its tip by the drive motor configured around it, and the hydraulic mechanism has the hydraulic cylinder arranged on the rear end side of the rotating body and operates a chuck mechanism for clamping and unclamping the rotating tool at the tip of the rotating body via the drawbar. The rotating device with a hydraulic mechanism according to claim 1 or claim 2, wherein a rotating spindle main body is constituted by the rotating mechanism and the hydraulic mechanism.

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