JP3168159B2 - Pallet fixing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for fixing a pallet exchangeably mounted on a machine of a machine tool to the machine.

[0002]

2. Description of the Related Art Conventionally, a fixing method shown in FIG. 3 is generally used for a pallet fixing device for detachably fixing a pallet to a machine table of a machine tool such as a machining center. This is the pallet 102 of the machine table 101
A hydraulic cylinder 103 is provided vertically and upward at the center of the mounting position, and a collet 105 at the tip of a piston rod 104 integral with the piston grips the neck of a pull stud 106 that is planted vertically and centrally downward of the pallet 102. The pallet 102 is pulled in, and the pallet's seating surface (contact surface) 101a
102a is pressed to perform clamping.

[0003] This clamp (seating) confirmation method is based on a method in which pressurized air is supplied from an air source P2 to a hole opened in a table-side seating surface 101a of the machine, and the two seating surfaces 1 that are brought into close contact with each other at the time of clamping.
A change in pressure of supply air due to air leakage from the air supply lines 01a and 102b is detected by an output signal of a pressure switch 107 provided in the middle of the air supply pipe 108.

[0004]

The method of confirming the clamp (seating) of the pallet fixing device described in the prior art is based on the fact that when chips or dust enter the seating surfaces 101a and 101b, the pallet pulling force by the hydraulic cylinder 103 is applied. (Clamping force)
Is set to a large force that can withstand workpiece machining,
Since the amount of air leaking from both seating surfaces is reduced by crushing chips or dust caught between the two seating surfaces, detection by the pressure switch 107 becomes difficult and detection accuracy becomes unstable. In addition, there is a problem that the positioning accuracy of the pallet is deteriorated and the processing accuracy is adversely affected.

[0005] The pallet fixing method and apparatus of the present invention have been made in view of the above-mentioned problems of the prior art, and an object thereof is to reduce the pallet clamping force at the time of confirming seating as compared with the time of processing a workpiece. It is another object of the present invention to provide a method and a device for fixing a pallet, which can reliably detect a seating failure without crushing chips, dust and the like bitten on a seating surface, thereby preventing deterioration of processing accuracy.

[0006]

According to a pallet fixing method of the present invention, a pallet is pulled into a machine table of a machine tool by a cylinder driven by hydraulic pressure or pneumatic pressure and the pallet is placed on a seating surface of the machine table. In the detachable pallet fixing method of pressing the seating surface that is the mating side of the machine, the pressurized air is supplied to the holes opened in the seating surface on the table side of the machine when both seating surfaces come into contact, and the seating defect is detected due to leakage. When checking seating, supply a lower fluid pressure to the cylinder than at the time of work processing so as not to crush chips and dust that have entered between both seating surfaces, to facilitate detection of seating failure, and to check seating after checking seating. A higher fluid pressure is supplied to the cylinder to fix the cylinder with a force that can withstand work processing.

Further, in the pallet fixing device of the present invention, the pallet is pulled into the machine table of the machine tool by a hydraulically or pneumatically driven cylinder and presses the seating surface of the pallet against the seating surface of the table. In the detachable pallet fixing device, a first air supply for supplying pressurized air when the two seating surfaces come into contact with a hole opened in the seating surface on the table side of the machine.
A supply means, a seating confirmation member for detecting a seating failure by a change in supply pressure due to air leakage from both seating surfaces of the first supply means, a second supply means for supplying a low-pressure fluid to the cylinder, Third to supply high pressure fluid to the cylinder
A supply means, and a switching means for supplying a low-pressure fluid pressure at the time of confirming seating to the cylinder and supplying a high-pressure fluid pressure after confirming the seating, and cutting chips or dust entering between the two seating surfaces at the time of confirming seating. A low-pressure fluid pressure is supplied so as not to crush, etc., so that seating failure can be easily detected, and after confirming the seating, a high-pressure fluid is supplied and fixed with a force that can withstand machining.

According to the pallet fixing method and apparatus of the present invention, for example, when a pallet having a work attached to the upper surface by an automatic pallet changing device is carried into the machine and transferred onto the machine table, the pressure is reduced. The pressure fluid adjusted to a low pressure through the valve is supplied to the cylinder by the second supply means, the pallet is drawn into the table of the machine, and the seating surface of the pallet is pressed against the seating surface of the table of the machine.

At this time, when the pressure air for seating confirmation is supplied from the first supply means to the hole opened on the seating surface on the table side of the machine, and the two seating surfaces pressed by the cylinder are in close contact with each other, Since there is no or very small amount of air leaking from the gap, the air pressure in the supply line of the first supply means rises to near the set pressure. This is detected by a pressure switch provided in the middle of the supply line, and a seating confirmation signal is output.

[0010] In the event that chips or dust are caught between the two seating surfaces, they are not crushed, so that a large gap is formed and the amount of air leakage increases. For this reason, the air pressure in the supply pipeline does not rise to the set pressure, and the seating confirmation signal is not output from the pressure switch. If this state continues for the set time of the timer and becomes the off-time, the machine is stopped as a seating failure and C
The worker is notified of the seating failure by a display device such as an RT.

When the seating confirmation signal is output from the pressure switch as described above, the pressure is switched from the second supply means to the third supply means, and the high pressure fluid at the original pressure is supplied to the cylinder, and the pallet is placed on the table of the machine. Is pulled in by a strong force to provide a clamping force that does not hinder work processing. In this way, when confirming seating, the pallet clamp is performed with a weak force due to the reduced fluid pressure, so the chips between the seating surfaces and dust etc. are not crushed and the gap between both seating surfaces is reduced, and the pallet checking is performed. Accuracy is stabilized, and the machining accuracy of the workpiece is not adversely affected.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of an indexing table device to which a pallet of a machining center is detachable, FIG.
FIG. 3 is a fluid pressure circuit diagram for pallet seating confirmation.

In FIG. 1, a flange 3 having a center hole formed in a first hydraulic cylinder 2 at substantially the center of the table body 1 of the machine is fixed with its axis perpendicular to the center, and the lower lid of the hydraulic cylinder 2 is attached to the flange 3. A flanged shaft 4 having a flange portion also serving as a vertical portion is fixed vertically. A rotating body 6 having a center hole formed in the second hydraulic cylinder 5 in a shaft portion of the flanged shaft 4 is supported so as to be movable in the axial direction and rotatable.
A worm wheel 8 is engaged via a key 9 so as to be relatively movable in the axial direction.

An indexing table 12 is concentrically fixed to the upper end of the rotating body 6 via an upper lid 11, and a short taper 12 for mounting a pallet is provided at the center of the upper surface of the indexing table 12.
a is formed, a flange end face adjacent to the lower side of the short taper 12 a is formed on the seating surface 12 b, and the positioning pin 13 is vertically and upwardly fixed on the upper lid 11.
A coupling 14 having a crown tooth shape is fixed to the upper lid 11 concentrically and downward, and a coupling 14B having the same tooth shape is also fixed to a corresponding position of the table main body 1 of the machine.

The hollow piston 15 of the first hydraulic cylinder 2 is provided on the lower side of the rotating body 6 so as to be relatively rotatable with its axial direction regulated. When pressure oil is sent from a pressure oil supply device (not shown) to the upper chamber of the first hydraulic cylinder 2, the indexing table 12 moves up via the rotating body 6 and the upper lid 11,
The engagement of the crown teeth of the couplings 14A and 14B is released, and the indexing table 12 can be rotated. In this state, the worm 7 is rotated by a servo motor (not shown) to perform indexing. After the indexing, the pressure oil is supplied to the upper chamber of the first hydraulic cylinder 2 and the indexing table 12 descends, and the crown teeth of the couplings 14A and 14B are engaged and pressed, so that the table body 1 of the indexing table 12 of the main machine 1 To be clamped.

Further, a hollow short spindle 16 is fitted in a center hole of the indexing table 12, and a piston rod 17 integrated with a piston 17a of the second hydraulic cylinder 5 is provided.
A collet 18 is provided at the tip of the collet 18.
Is inserted into the center hole of the short spindle 16 so as to be vertically movable.

The pallet 19, which is exchangeably attached to the indexing table 12, has a plate 21 concentrically fixed to the bottom surface.
a, the lower surface adjacent to the short tapered hole 21a is formed in the seating surface 21b, the pull stud 20 is fixed concentrically and downward on the bottom surface of the pallet 9, and the positioning pin 13 is not moved, and the axial movement is performed. A blind hole 19a is bored for possible insertion.

An oil passage 22 communicating with the upper chamber of the second hydraulic cylinder 5 and an oil passage 23 communicating with the lower chamber are formed in the flanged shaft 4 and the rotating body 6. Then, the pressurized oil is supplied to the upper chamber of the second hydraulic cylinder 5, the collet 18 descends together with the piston 17a, grasps the neck of the pull stud 20, pulls the pallet 19 downward, and the seating surface (lower surface) of the plate 21 When the bottom surface 21b comes into close contact with the seating surface (flange end surface) 12b of the indexing table 12, the short taper 12a and the short taper hole 21b are fitted without any gap, and the pallet 19 is positioned and clamped.

An air supply passage 24 for pressurized air is opened in the seating surface 12b of the indexing table 12. As shown in FIG. 2, the air supply passage 24 is provided with a first switching valve 30 from an external air source P2. A pressure switch 25 adjusted so as to be turned on substantially at the set pressure is provided in the middle of the air supply path 24.

On the other hand, an oil passage 22 communicating with the upper chamber of the second hydraulic cylinder 5 and an oil passage 23 communicating with the lower chamber are connected to a second switching valve 26 or a third switching valve from a supply source P1 of an external hydraulic device. 2
7 is supplied with the pressure oil switched by either one of them. Further, a pressure reducing valve 31 is provided in the supply line 29 to the second switching valve 26 which branches off from the middle of the source pressure supply line 28 to the third switching valve 27. Pipe line 3 communicating with passage 22 and oil passage 23
Check valves 33 and 34 with pilots are provided in the middle of 1 and 32, respectively. Further, check valves 37 and 38 with pilots are respectively provided in the middle of pipes 35 and 36 communicating from the third switching valve 27 to the oil passages 22 and 23. The conduit 39 and the conduit 40 communicating therewith are for drainage.

Next, the operation of the embodiment of the present invention will be described. Now, a pallet 19 to which a work (not shown) is attached is carried in by an automatic pallet changer (not shown) and placed on the indexing table 12 of the machine, and the second switching valve 26 is turned off for both SOL1 and SOL2. Only the SOL3 is turned ON in the third switching valve 27, and the pressure oil is supplied to the lower chamber of the hydraulic cylinder 5 through the open port of the third switching valve 27. 18 is open. When the pallet 19 is transferred onto the indexing table 12, the first switching valve 30 is turned ON, and air is blown out from the hole at the tip of the air supply 24 which opens in the seating surface 12 a of the indexing table 12.

Next, SOL3, SO of the third switching valve 27
L4 is turned off, and at the same time, the SO of the second switching valve 26
L2 is turned on, and the check valve 37, 38 causes the line 3
5 and 36 are closed, and the pressure reducing valve 3
The pressure oil adjusted to a low pressure via the hydraulic cylinder 5
Is supplied to the upper chamber. As a result, the piston 17a moves to the lower end position, the neck of the pull stud 20 is gripped by the collet 18, the pallet 19 is pulled into the indexing table 12, and the seating surface 21b of the plate 21 is moved to the indexing table 1.
2 and a short taper 1
The first clamping of the pallet 19 is performed by fitting the short taper hole 21b with the short taper hole 21b without gap.

At this time, if any dust or dust enters between the seating surfaces 16b and 21b, the pallet clamp is performed with a weak pressure through the pressure reducing valve 31. And dust and the like are not crushed.
A gap is formed between b and 21b. Therefore, air flows out from the hole opened in the seating surface 12b at the tip of the air supply passage 24 through the gap, and the pressure in the air supply passage 24 does not increase to the set pressure. Therefore, the pressure switch 25 remains OFF. If this state continues for the set time of the timer forever, it will be off time and the machine will stop alarming,
The operator is notified of the seating failure by a display member such as a CRT, and at the same time, the first switching valve 30 is turned off.

However, if the two seating surfaces 16b and 21b come into close contact with the first positioning clamp, the pressure switch 2
5 turns ON, and a pallet seating confirmation signal is output.
At the same time as the first switching valve 30 is turned off by this output signal, both the solenoids SOL1 and SOL2 of the second switching valve 26 are turned off, and at the same time, SOL4 of the third switching valve 27 is turned on. As a result, the pipelines 31 and 32 are closed by the check valves 33 and 34, and high-pressure hydraulic oil that does not pass through the pressure reducing valve 31 is supplied to the upper chamber of the second hydraulic cylinder 5, and the pallet is strong with a cutting force. Nineteenth second clamps are performed.

Next, the work (not shown) mounted on the pallet 19 is cut, and when the cutting force is over, the SOL3 of the third switching valve 27 is turned on, and the lower chamber of the hydraulic cylinder 5 is turned on. The pressurized oil is supplied, the piston 17a rises, the collet 18 opens, and the lower surface of the pull stud 20 is slightly pushed up at the upper end of the piston rod 17 to release the pallet clamp. It is carried out of the machine.

It should be noted that there is no problem even if SOL2 of the second switching valve 26 is kept ON during the second strong clamping of the pallet 19, and that the second switching valve 26 is released while the pallet 19 is being unclamped. There is no problem even if SOL1 is turned ON. In the present embodiment, the pallet 19 is
Although the hydraulic cylinder 5 is used as the unclamping cylinder, it may be an air cylinder.

[0027]

Since the present invention is configured as described above, the following effects can be obtained. The pallet clamping force is small when checking the pallet seating, and large when processing the work.When chips or dust enter the seating surface, it is crushed to prevent the gap from becoming smaller, improving the pallet seating accuracy. It is possible to prevent the inconvenience that the workpiece is processed with inaccurate work by cutting the seating surface while cutting chips, dust and the like are bitten.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of an indexing table device to which a pallet of a machining center is detachable.

FIG. 2 is a fluid pressure circuit diagram for pallet seating confirmation.

FIG. 3 is a fluid pressure circuit diagram for confirming pallet seating according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 This machine table main body 2 1st hydraulic cylinder 5 2nd hydraulic cylinder 6 Rotating body 7 Worm 8 Worm wheel 12 Indexing table 12a Short taper 12b, 21b Seating surface 14A, 14B Crown-shaped coupling 15 Hollow piston 16 Short spindle 17 Piston rod 18 Collet 19 Pallet 20 Pull stud 21 Pallet mounting plate 21a Shower taper hole 24 Air supply path 25 Pressure switch 26 Second switching valve 27 Third switching valve 30 First switching valve 31 Pressure reducing valve

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B23Q 17/00 B23Q 3/00 B23Q 3/06 304 B23Q 7/00

Claims (2)

(57) [Claims] 1. A removable pallet is drawn into a machine machine table of a machine tool by a hydraulically or pneumatically driven cylinder and presses a mating seating surface on the machine table side with a mating seating surface on the pallet side. Pallet fixing method, pressurized air is supplied to the holes opened in the seating surface on the table side of this machine when both seating surfaces are in contact, and seating failure is detected due to leakage. Supplying a lower fluid pressure to the cylinder at the time of machining the work so as not to crush the swarf or dust, which facilitates detection of seating failure, and supplying a higher fluid pressure to the cylinder at the time of seating confirmation after the seating is confirmed. A pallet fixing method characterized in that the pallet is fixed with a force that can withstand processing. 2. A detachable pallet fixing device which draws a pallet into a table of a machine tool of a machine tool by a hydraulic or pneumatic pressure driven cylinder and presses the pallet-side seating surface against the table-side seating surface. A first supply means for supplying pressurized air when the two seating surfaces come into contact with a hole opened on the seating surface on the table side of the machine; and a change in supply pressure due to air leakage from both seating surfaces of the first supply means. A seating confirmation member that detects a seating failure, a second supply unit that supplies a low-pressure fluid to the cylinder, a third supply unit that supplies a high-pressure fluid to the cylinder, and a low-pressure unit that supplies a low-pressure fluid to the cylinder. A switching means for supplying a fluid pressure and supplying a high fluid pressure after the seating is confirmed is provided, and a low pressure fluid pressure is supplied so as not to crush the chips and dust which have entered between the seating surfaces at the time of the seating confirmation. A pallet fixing device, wherein a seating defect is easily detected, and after confirming the seating, a high-pressure fluid is supplied to fix the pallet with a force that can withstand machining.