JPH04322829A - Fluid pressure clamp with clamp locking device - Google Patents

Abstract

PURPOSE:To make a clamp in a small size, and also, to surely execute its unclamping operation, in the fluid pressure clamp of a form for locking an object to be fixed such as a die, to a clamping state, even when fluid pressure for the clamp is abnormally reduced. CONSTITUTION:On the upper side of a first cylinder hole 10 provided on the front lowering part, a second cylinder hole 28 is provided horizontally. On the rear side of a first piston 12, a first operating chamber 13 for driving a clamp is formed, and to the front part of its first piston 12, a clamping tool 7 is fixed. On the rear side of a second piston 29 inserted into a second cylinder hole 28, a second operating chamber 30 for locking is formed, and on the front side of its second operating chamber 29, a third operating chamber 34 for driving an unclamp is formed. In the rear front part of a second piston 29, the wedge type pressure surface 39 and a lock release engaging part A are provided in order from the rear, and in the rear upper part of a first piston 12, the pressure receiving surface 38 and a part B to be engaged are provided in order from the rear.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a fluid pressure clamp that presses objects to be fixed, such as molds and work pallets, to the fixed base of processing machines such as injection molding machines and machining centers. A clamp locking device is attached to the pressure clamp, and the clamping locking device operates to prevent the object to be fixed from being unclamped by external force when the clamping fluid pressure is abnormally reduced.

0002

2. Description of the Related Art A hydraulic clamp with a clamp locking device of this type is disclosed in Japanese Patent Laid-Open No. 1-154833. This is the first clamp for the clamp, as shown in Figure 5.
The fluid pressure in the first working chamber 313 of the cylinder 309 causes the first piston 312 to advance from the unclamping position Y (double-dashed line) to the clamping position X (solid line). A lock chamber 326 is orthogonally communicated with the lock chamber 313, and a lock wedge 327 is inserted into the lock chamber 326.

This wedge 327 is caused by the fluid pressure in the second working chamber 393 of the second cylinder 329 to move the second piston 33
9, the lock position M advances into the first working chamber 313
(solid line diagram) and the lock release position N (two-dot chain diagram) where the lock chamber 326 is retracted into the lock chamber 326. A third working chamber 340 is formed below the second piston 339, and a locking pressure spring 395 is attached to the second working chamber 393.

When switching the clamp arm 307 from the unclamped state shown in the chain double-dashed line to the clamped state shown in the solid line, the pressure fluid is discharged from the third working chamber 340, and the first working chamber 313 and the second working chamber Pressure fluid is supplied to 393 and 393. Then, the first piston 312 advances leftward from the unclamping position Y, swinging the clamp arm 307 toward the object 302 to be fixed. At the same time, the wedge 327 advances from the unlocked position N toward the locked position M due to the fluid pressure in the second working chamber 393 and the elastic force of the pressing spring 395, and the wedge surface 348 moves toward the first piston 31.
The wedge engages with the wedge receiving surface 349 of No. 2. The first piston 312 is strongly pressed to the clamp position X by the combined force of the wedge engagement force of the wedge 327 that is subsequently driven to advance and the fluid pressure in the first working chamber 313.

[0005]

SUMMARY OF THE INVENTION The above conventional structure has the following problems. The second cylinder 329 is the first cylinder 30
Since it protrudes upward from 9, the height of the hydraulic clamp increases.

Furthermore, in the above-mentioned wedge engagement type hydraulic clamp, at the end of the clamp drive, the wedge 327 is locked against the dynamic frictional force acting between the wedge surface 348 and the wedge receiving surface 349. Lock drive to position M. On the other hand, at the beginning of the unclamp drive, it is necessary to drive the wedge 327 to the unlock position N against a static friction force that is much larger than the dynamic friction force. The reason for this is that the coefficient of static friction is much larger than the coefficient of dynamic friction, and the excessive surface pressure at the end of the clamp drive causes
It is thought that this is because the lubricating oil between 48 and 349 is pushed out and metal contact occurs.

In locking and driving the wedge 327, the fluid pressure in the second working chamber 393 and the locking pressure spring 39
Since the resultant force with the elastic force of 5 is utilized, the locking pressing force is large. Therefore, in order to reliably drive the wedge 327 to unlock, it is necessary to make the second piston 339 large in diameter to increase the cross-sectional area of the second working chamber 340. Further, the inclination angle α of the wedge surface 348 needs to be set to a value as small as possible in order to reliably unlock the wedge 327. Therefore, the lower part of the first piston 312 protrudes backward. As described above, the hydraulic clamp becomes large because it is taller, the second piston 339 has a larger diameter, and the first piston 312 also has a longer length.

In addition, during the period from the start of clamp drive to the start of wedge engagement shown in the chain double-dashed line in the figure, the second locking
Due to the resultant force of the fluid pressure in the working chamber 393 and the locking pressure spring 395, the lower surface of the wedge 327 strongly contacts the outer peripheral surface of the first piston 312. Therefore, the outer circumferential surface thereof is damaged, and fluid leakage from the first working chamber 313 is likely to occur. This problem becomes a significant problem when the clamping thickness of the object to be fixed, such as the mold 302, becomes large. That is,
When the clamp thickness increases, the load on the first piston 312 increases when the swing angle of the clamp arm 307 is small, and the outer peripheral surface of the first piston 312 and the wedge 32
This is because the degree of interference with the lower surface of 7 also increases.

Furthermore, the operation of returning the first piston 312 from the clamp position The operating force for clamping is weak. Therefore, when foreign matter such as dust or rust gets caught in the sliding surface of the first piston 312, the unclamping operation may not be performed due to the resistance. An object of the present invention is to downsize a hydraulic clamp, to maintain a good airtight state of a first working chamber for the clamp, and to perform an unclamping operation reliably.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention is characterized in that a fluid pressure clamp is constructed as follows. (Invention of Claim 1) For example, FIG.
Alternatively, as shown in FIG. 3, the second cylinder hole (28) is arranged in the housing (4) so as to intersect with the first cylinder hole (10) extending in the front-rear direction, and the above-mentioned The first piston (1) inserted into the first cylinder hole (10) of
2) A first working chamber (13) for driving the clamp is formed on the rear side, and a clamp tool (13) is formed on the front side of the first piston (12).
7), connect the clamping tool (7) to the first piston (12), and connect the second cylinder hole (28) to the first piston (12).
) A second working chamber (30) for clamp locking is formed on the retreating side of the second piston (29) inserted into the second piston (29), which directly communicates with the first working chamber (13). A third working chamber (34) for unclamping drive is formed on the forward side of the second piston (29), and the first piston (12)
) A wedge-type pressing surface (39) for clamp locking is attached to the retreating side portion of the second piston (29) facing the rear part of the second cylinder hole (28) with respect to the axis (Y) of the second cylinder hole (28). Second
The above-mentioned wedge-type pressing surface (39) is provided at the rear of the first piston (12), and is provided in a shape that becomes narrower toward the piston advancing side.
), and an engaged portion (B) that faces the above-mentioned engaging portion (A).

(Invention according to claim 2) In the hydraulic clamp according to claim 1, for example, as shown in FIG. 1, the first cylinder hole (10) is formed in the front surface (4a) of the housing (4). The first cylinder hole (
10), the second cylinder hole (28) is arranged in the front-rear direction on the upper side. Note that the first cylinder hole (
10) and the axis (X) of the second cylinder hole (28)
The intersection angle (β) with Y) is preferably within the range of 15 degrees to 50 degrees, particularly preferably within the range of 25 degrees to 40 degrees.

(Invention according to claim 3) In the hydraulic clamp according to claim 1, for example, as shown in FIG. 3, the first cylinder hole (10) is provided on the front surface of the housing (4).
is opened downward toward the front, and the second cylinder hole (28) is arranged vertically behind the first cylinder hole (10). The intersection angle (β) between the axis (X) of the first cylinder hole (10) and the axis (Y) of the second cylinder hole (28) is preferably within the range of 40 degrees to 75 degrees. , is particularly preferably within the range of 50 degrees to 65 degrees.

[0013]

[Operation] The present invention operates as follows, as shown in FIG. 1, for example. (b) In the unclamped state shown in the figure, the pressure fluid in the first working chamber 13 and the second working chamber 30 is discharged, and the pressure fluid is supplied to the third working chamber 34. As a result, the second piston 29 retreats to the rear side, and the engaging portion A retreats the second piston 12 to the unclamping position via the engaged portion B.

When switching from the unclamped state described above to the clamped state shown in FIG. do. Then, the first piston 12 and the second piston 29 move forward due to the fluid pressure, and the clamping tool 7 attaches to the object to be fixed (here, the mold) 2.
Press and contact from above. Subsequently, the second piston 29 advances by a locking stroke relative to the first piston 12 whose advancement movement is blocked. As a result, the pressure receiving surface 3
8, the wedge-type pressing surface 39 engages with the wedge in a forward direction.
The first piston 12 is pressed against the circumferential surface of the first cylinder hole 10, and the second piston 29 is pressed against the circumferential surface of the second cylinder hole 28.

[0015] Even if the pressure in the first working chamber 13 and the second working chamber 30 drops abnormally due to fluid leakage in the pressure fluid supply piping, the first piston 12 is held at the clamp position. . That is, when the fluid pressure disappears, disturbance forces such as gravity and processing reaction force acting on the object 2 to be fixed try to move the first piston 12 back, albeit slightly, via the clamp tool 7. Then, the pressure receiving surface 38 increasingly bites into the wedge-type pressing surface 39 of the second piston 29, which is frictionally fixed in the second cylinder hole 28, and is strongly locked.

Furthermore, during the unclamping operation, the first piston 12 can be strongly retracted via the second piston 29 by the fluid pressure in the third working chamber 34.
Even if foreign matter such as dust or rust gets caught in the sliding surfaces of the first piston 12 or the clamping tool 7, the unclamping operation can be performed reliably.

[0017]

[Effects of the Invention] The present invention has the following effects because it is constructed and operates as described above. Unlike the conventional example described above, the second cylinder hole does not need to protrude orthogonally upward from the first cylinder hole, so the height of the hydraulic clamp is short. Further, since the locking stroke is shortened since both cylinder holes are arranged in a cross-like manner, the length of the first piston can be shortened, and the length of the hydraulic clamp in the front-rear direction is also shortened. With the above, the hydraulic clamp can be made compact. In addition, since the locking stroke described above is short, the clamp operation time is also shortened.

Furthermore, since the two cylinder holes are arranged in a cross-shaped manner, the second piston does not interfere with the sealing surface of the first cylinder hole, and the hydraulic clamping is performed while keeping the sealing surface in good condition. The lifespan of can be extended.

Furthermore, since the first piston can be strongly retracted via the second piston by the fluid pressure in the third working chamber, the unclamping operation can be performed reliably.

Furthermore, as shown in claim 2 or 3, in the hydraulic clamp of claim 1, the first cylinder hole is opened forward downward in the front face of the housing, and the second cylinder hole is opened downwardly in the front side of the housing. When arranged above the cylinder hole in the longitudinal direction or arranged behind the first cylinder hole in the vertical direction, the fillet portion of the housing can be effectively used, so that the hydraulic clamp can be made even more compact.

[0021]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. (First Embodiment) The operation explanatory diagram of FIG. 1 and the plan view of FIG. 2 show the first embodiment. As shown in FIG. 1A and FIG. 2, a mold 2, which is an object to be fixed, is fixed to a fixing table 1 of an injection molding machine by a hydraulic clamp (hydraulic clamp) 3. This hydraulic clamp 3 has both side walls 5 and 5 of its housing 4.
5 is fixed to the fixing base 1 by two bolts 6, 6, and a clamping tool 7 extended from the housing 4 presses the mold 2 diagonally from above.

A hydraulic first cylinder 9 is provided in the housing 4 in an oblique direction. This first cylinder 9 is
A first cylinder hole 10 that opens forward downward in the front surface 4a of the housing 4, a first piston 12 that is inserted into the cylinder hole 10 through a packing 11 in an oil-tight manner, and the first
A first clamp drive plate formed on the rear upper side of the piston 12.
A working chamber 13 is provided. The clamp tool 7 is directly extended from the front part of the first piston 12 toward the lower front side. Incidentally, the inclination angle θ of the cylinder hole 10 is set to about 30 degrees here, and is preferably set within the range of 25 degrees to 40 degrees, but may be within the range of 15 degrees to 50 degrees. Good too.

The above first piston 12 has a spring housing hole 1.
It is pressed forward and downward by a clamping pressure spring 16 inserted into the clamp 5, and is prevented from moving beyond a predetermined amount by a stopper pin 18. This stopper pin 18 is secured by the two bolts 6, 6 in a pin insertion hole 19 formed in the front lower part of the housing 4, and functions to guide the clamp tool 7 in a straight line.

A second cylinder 27 is arranged above the first cylinder 9. That is, the first cylinder hole 10 described above
A second cylinder hole 28 having a smaller diameter than the first cylinder hole 10 is horizontally formed above the cylinder hole 10 . The intersecting angle β of the axes X and Y of these cylinder holes 10 and 28 is the same value as the inclination angle θ of the first cylinder hole 10, which is about 30 degrees.

[0025] Packing 31 is installed in the second cylinder hole 28.
The second piston 29 is inserted in an oil-tight and movable manner through the second piston 29, and a second working chamber 30 for clamp locking is formed on the rear side of the second piston 29, and a second working chamber 30 for unclamping is formed on the front side of the second piston 29. A third working chamber 34 is formed for this purpose. The second piston 29 is pressed forward by a locking pressure spring 33 mounted between the second piston 29 and the end plate 32. The second working chamber 30 is communicated with the clamp oil supply/drainage port 24 via the oil passage 23 and directly with the first working chamber 13 . Further, the third working chamber 34 is communicated with an unclamping oil supply/drainage port 36 via an oil passage 35.

At the bottom of the second piston 29, there is a wedge-type pressing surface 39 for clamp locking, which is formed upwardly toward the front.
The interference prevention groove 40 and the lock release engaging portion A are provided in this order from the rear. Note that the inclination angle α of the wedge-type pressing surface 39
is set to about 12 degrees here, but can be set to any value depending on the application of the clamp. Further, at the rear upper part of the first piston 12, a pressure receiving surface 38 that contacts the wedge-type pressing surface 39 and an engaged portion B that faces the engaging portion A are provided in order from the back. There is.

The above hydraulic clamp 3 operates as follows. In the unclamped state shown in FIG. 1(b), the first working chamber 1
The pressure oil in the third and second working chambers 30 is discharged, and the pressure oil is supplied to the third working chamber 34. This allows the second
The piston 29 is retracted rearward, and the engaging portion A retracts the first piston 12 via the engaged portion B to the unclamped position on the rear upper side.

When switching from the unclamped state described above to the clamped state shown in FIG. supply Then, the first piston 12 and the second piston 29 advance due to the hydraulic pressure, and the clamp tool 7 presses against the mold 2 from above.

Subsequently, the second piston 29 advances forward relative to the first piston 12 whose advancement movement has been blocked. As a result, the wedge-type pressing surface 39 comes into wedge engagement with the pressure receiving surface 38, and the second piston 29 is strongly pressed against the circumferential surface of the second cylinder hole 28. As a result, the second piston 29 holds the first piston 12 at the clamp position. In addition, the above wedge-type pressing surface 3
The materials of the pressure receiving surface 9 and the pressure receiving surface 38 are selected or surface treated so as to reduce the coefficient of friction between these contact surfaces. Similarly, the coefficient of friction between the contact surfaces between the first piston 12 and the first cylinder hole 10 is also reduced. Contrary to the above, the material between the contact surfaces of the second piston 29 and the second cylinder hole 28 is selected from a material having a relatively large coefficient of friction or subjected to surface treatment.

When the hydraulic pressure in the first working chamber 13 and the second working chamber 30 decreases abnormally due to pressure oil leakage from the pressure oil supply piping, etc., the gravity, processing reaction force, etc. acting on the mold 2 The disturbance force is applied to the first piston 1 via the clamp tool 7.
Trying to push 2 back, even if only slightly. Then, the second
The pressure receiving surface 38 further bites into the wedge-type pressing surface 39 of the second piston 29, which is frictionally fixed in the cylinder hole 28, and locks even more strongly.

The device for detecting the clamped state and unclamped state may be a device that detects the position of the first piston 12 or a device that detects the position of the second piston 29. .

The above configuration provides the following advantages. Unlike the conventional example described above, the second cylinder 27 does not need to protrude orthogonally upward from the first cylinder 9, so the height of the hydraulic clamp 3 is short. Also, both cylinder holes 10・
Since the locking stroke is shortened since the pistons 28 are arranged in a crossed manner in a tapered rear shape, the length of the first piston 12 can be shortened, and the length of the hydraulic clamp 3 in the front-rear direction is also shortened. With the above, the hydraulic clamp 3 can be made compact. In addition, since the locking stroke described above is short, the operating time when driving the clamp is shortened, and the wedge-type pressing surface 3
It is possible to set the angle of inclination α of 9 to a desired value that is compatible with the clamping operation.

Since both cylinder holes 10 and 28 are arranged in an intersecting manner, the second piston 29 does not interfere with the sealing surface of the first cylinder hole 10, and the sealing surface can be kept in good condition. Therefore, the life of the hydraulic clamp 3 can be extended.

The clamping force of the hydraulic clamp 3 can utilize not only the thrust of the pistons 12 and 29 but also the elastic force of the pressing springs 16 and 33, so its clamping ability is large.

Since each sliding portion of the hydraulic clamp 3 is immersed in oil, it is possible to achieve long-term maintenance-free operation without oiling.

When the hydraulic clamp 3 is clamped, the clamp tool 7 comes into contact with the mold 2 as described above, and then the second piston 29 advances toward the first piston 12 and locks the first piston 12. Therefore, the tolerance range for the clamp thickness of the mold 2 is wide.

Note that the above first embodiment can be modified as follows. It is also possible to omit both or one of the above-mentioned pressing springs 16 and 33. Hydraulic clamp 3
Instead of driving the clamping tool 7 in a straight line by the first piston 12, the clamping tool may be driven to swing as in the conventional example, or a scale-type clamping tool may be driven to swing. It's okay. Further, the first cylinder 9 and the second cylinder 27 may be pneumatic cylinders instead of hydraulic cylinders.

FIGS. 3 and 4 show a second embodiment and a third embodiment, respectively. In each embodiment, the same reference numerals are attached to the same elements as in the first embodiment described above.

(Second Embodiment) FIG. 3 shows a second embodiment. In this case, a second cylinder hole 28 is formed in the vertical direction behind the first cylinder hole 10, a second working chamber 30 is formed above the second piston 29, and a second working chamber 30 is formed below the second piston 29. A third working chamber 34 is formed. The inclination angle θ of the first cylinder hole 10 is set to about 30 degrees, as described above. Also, both cylinder holes 10・
The intersecting angle β of the axes X and Y of 28 is set to approximately 60 degrees here, but it may be within the range of 40 degrees to 75 degrees, or within the range of 50 degrees to 65 degrees. is preferred.

[0040] On the upper part of the second piston 29, a wedge-type pressing surface 39 for clamp locking, which is formed downwardly downward, an interference prevention groove 40, and a lock release engaging part A are provided in order from the top. There is. Note that the inclination angle α of the wedge-type pressing surface 39
is set at approximately 12 degrees as described above. Further, at the rear of the first piston 12, a pressure receiving surface 38 that contacts the wedge-type pressing surface 39 and an engaged portion B that faces the engaging portion A are provided in order from the rear side. . Further, as for the pressing spring, the clamping pressing spring of the first embodiment is omitted, and only the locking pressing spring 33 is provided. The second embodiment described above also provides substantially the same advantages as the first embodiment.

(Third Embodiment) FIG. 4 shows a third embodiment. A sliding shuttle member 51 is interposed between the upper surface of the mold 2 and the clamp tool 7 so as to be slidable within a certain range in the front and rear directions. This shuttle member 51 is made of nitrided alloy steel and is plated, and is pushed forward by an advancing spring 53 while being inserted into a support groove 52 on the lower surface of the clamp tool 7. The shuttle member 5
A stopper pin 55 inserted into the floating hole 54 prevents forward movement beyond a predetermined amount.

The shuttle member 51 operates as follows when switching from the illustrated clamped state to the unclamped state. When the first piston (not shown here) is driven backward and upward, slippage occurs between the shuttle member 51 frictionally fixed to the mold 2 and the clamp tool 7, leaving the shuttle member 51 behind. In this state, only the clamp tool 7 is driven rearward and upward. The first piston, which is subsequently driven backward, unclamps the clamping tool 7 and the shuttle member 51 rearward and upward, and the mold 2 is unclamped. This ensures that the unclamping operation is performed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operation of a hydraulic clamp according to a first embodiment, in which (a) is a longitudinal cross-sectional side view showing a clamped state, and (b)
) is a vertical sectional side view showing the unclamped state.

FIG. 2 is a plan view of the above hydraulic clamp.

FIG. 3 is an explanatory diagram of the operation of the hydraulic clamp of the second embodiment, and is a diagram corresponding to FIG. 1.

FIG. 4 is a partial view of a hydraulic clamp according to a third embodiment.

FIG. 5 is a diagram showing a conventional example and corresponding to FIG. 1;

[Explanation of symbols]

4... Housing, 4a... Front, 7... Clamp tool, 10...
1st cylinder hole, 12... 1st piston, 13... 1st working chamber, 28... 2nd cylinder hole, 29... 2nd piston, 30
...Second working chamber, 34...Third working chamber, 38...Pressure receiving surface, 39
... wedge-type pressing surface, A... engaging part, B... engaged part, X... axial center of first cylinder hole 10, Y... axial center of second cylinder hole 28,
β...Cross angle.

Claims (3)

[Claims] Claim 1: Within the housing (4), a second cylinder hole (
28) are arranged so as to cross each other in a tapered shape, and the above-mentioned 1st
A first working chamber (13) for driving the clamp is formed on the rear side of the first piston (12) inserted into the cylinder hole (10),
A clamp tool (7) is arranged on the front side of the first piston (12), and the clamp tool (7) is connected to the first piston (12) and inserted into the second cylinder hole (28). A second piston (29) for clamp locking is provided on the backward side of the second piston (29), which communicates directly with the first working chamber (13).
A working chamber (30) is formed, while a third working chamber (34) for unclamping drive is formed on the forward side of the second piston (29), and a third working chamber (34) for unclamping drive is formed on the forward side of the second piston (29). A wedge-type pressing surface (39) for clamp locking is provided on the retreating side portion of the second piston (29) facing the rear part of the second piston (29). It is provided in a shape that narrows toward the piston advancing side, and is provided with an engaging part (A) for unlocking, which contacts the wedge-type pressing surface (39) at the rear of the first piston (12). A fluid pressure clamp with a clamp locking device, characterized in that a pressure receiving surface (38) is provided, and an engaged portion (B) facing the above-mentioned engaging portion (A) is provided. 2. The hydraulic clamp according to claim 1, comprising:
The first cylinder hole (10) is opened in the front surface (4a) of the housing (4) downward in the front direction, and the second cylinder hole (28) is opened above the first cylinder hole (10) in the front-rear direction. It is arranged and configured in . 3. The hydraulic clamp according to claim 1, comprising:
The first cylinder hole (10) is opened in the front face (4a) of the housing (4) in a downward direction, and the second cylinder hole (28) is opened in the rear side of the first cylinder hole (10) in a vertical direction. A structure arranged in a direction.