JP6430893B2 - Clamping device - Google Patents

Description

  The present invention relates to a clamping device used for fixing an object to be fixed such as a pallet, a work piece, a mold or the like on a base such as a table or a work pallet in a machine tool such as a machining center.

  As this type of clamping device, a pull stud provided on the lower surface side of the object to be fixed, a cylinder provided on the upper surface side of the base and incorporating the piston, and provided on the upper portion of the piston for gripping the head of the pull stud A collet that pulls the pull stud held by the collet downward by supplying pressure oil to the upper space in the cylinder and lowering the piston. It is known that an unclamping operation is performed in which a collet is opened and a pull stud is released by supplying pressure oil to a lower space to raise a piston (see Patent Document 1 below).

  As other conventional clamping devices, a pull stud provided on the lower surface side of the object to be fixed, a cylinder provided on the upper surface side of the base and incorporating the piston, and a peripheral surface of the upper opening recess of the piston A plurality of engagement balls that are freely provided and engage and hold the pull stud, and are engaged and held by the engagement balls by lowering the piston by a biasing force of a spring disposed in the cylinder. Clamping operation is performed in which the pull stud is pulled downward, while unclamping operation in which the engagement of the pull stud by the engagement ball is released by supplying pressure oil to the lower space in the cylinder and raising the piston. Is also known (see Patent Document 2 below).

JP 2010-76061 A Japanese Patent Laid-Open No. 10-217057

However, in the case of the former clamping device, the clamping operation is performed by supplying pressure oil to the upper space of the cylinder. Therefore, if the original pressure is lost due to some trouble, a safety problem may occur.
In the case of the former clamping device, since the collet is opened and closed by raising and lowering the piston, it is necessary to increase the lifting stroke of the piston, resulting in a problem that the device becomes large.

On the other hand, in the latter clamping device, since the clamping operation is performed by the biasing force of the spring, the problem of loss of the original pressure does not occur unlike the former clamping device, and it can be said that it is preferable in terms of safety.
However, in the case of the latter clamping device, since the pull stud is engaged and held by the engagement ball, there is a problem in that the surface pressure of both engagement portions increases and the total pulling force cannot be increased. It was. Also, in this device, if the engagement ball falls into the upper opening recess of the piston, it becomes impossible to insert the pull stud into the recess, so a mechanism for preventing this is necessary, and the structure is complicated. There was a risk of increasing costs.

The object of the present invention is to make the overall configuration of the apparatus compact and to increase the total pulling force, so that the structure of the part holding the pull stud is complicated and the cost increases accordingly. It is an object of the present invention to provide a clamping device that does not incur the risk of inconvenience.
Another object of the present invention is to provide a clamping device that can be used more safely without the risk of problems due to loss of the original pressure during the clamping operation.

  In order to achieve the above object, the present invention comprises the following aspects.

1) A clamping device for fixing an object to be fixed on a base, a pull stud provided on the lower surface side of the object to be fixed, a cylinder provided on the upper surface side of the base and incorporating a piston, A collet provided at the top so as to be openable and closable to grip the pull stud, a clamp driving means for moving the piston downward so that the pull stud gripped by the collet is pulled, and an unclamp driving means for moving the piston upward A clamp device comprising: a collar disposed at an upper portion of the cylinder so as to surround the collet, and a collar for opening and closing the collet by being lifted and lowered by a lifting means.

2) The clamp device according to 1) above, wherein the clamp driving means comprises a clamp spring that applies a downward biasing force to the piston.

3) The elevating means for elevating the collar includes a collar elevating spring for applying a biasing force to the collar so that the collar is held at the collet closed position which is the upper limit of the elevating stroke. Clamping device.

4) The clamping device according to any one of 1) to 3) above, wherein the pull stud is pushed up by the piston during unclamping.

According to the clamping device of the above 1), the collet is opened and closed by raising and lowering the collar arranged around it, so that the lifting stroke of the piston can be the minimum necessary for clamping and unclamping, Therefore, the apparatus can be miniaturized.
Further, according to the clamping device of 1) above, since the pull stud is pulled downward while being held by the collet, the surface pressure of the engaging portion between the pull stud and the collet is higher than that of the engaging ball. The total pulling force can be increased.
In addition, according to the clamping device of 1) above, by using a collet as a means for holding the pull stud, a mechanism for preventing the piston from falling into the upper opening recess of the piston like an engagement ball is unnecessary. Therefore, the structure of the same part is simplified and there is no risk of increasing the cost.

  According to the clamp device of the above 2), since the clamp driving means is composed of a clamp spring that applies a downward biasing force to the piston, there is no possibility of causing a problem of loss of the original pressure as in the case of the fluid pressure mechanism. It can be used safely.

  According to the clamp device of the above 3), the collar is held at the collet closed position, which is the upper limit of the lifting stroke, by the urging force of the collar raising spring, so that the original pressure is lost as in the case of using the fluid pressure mechanism. There is no risk of malfunction, and the collar can securely hold the collet in a closed state and can be used safely.

  According to the clamp device of the above 4), the pull stud is pushed up by the piston at the time of unclamping, so that the collet and the collar are prevented from sticking, and further, the contact surface between the fixed object and the base at the time of clamping is prevented. Can do.

It is a vertical sectional view showing a state at the time of clamping of the clamping device of the present invention. It is a vertical sectional view which shows the state at the time of unclamping of the clamp apparatus of this invention.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.
In this embodiment, the present invention is applied to a clamping device used to fix a pallet (fixed object) on a table (base) in a machine tool such as a machining center.

  As shown in FIGS. 1 and 2, the clamping device (1) according to the present invention includes a pull stud (4) provided on the lower surface side of the pallet (3) and an upper surface side of the table (2) and a piston. A cylinder (5) with a built-in (6), a collet (7) that can be opened and closed at the top of the piston (6) and grips the pull stud (4), and a pull stud ( 4) Clamping spring (8) that exerts an urging force on piston (6) so that it is pulled downward, and pressure oil to cylinder (5) is used to resist the urging force of clamping spring (8). The unclamping hydraulic mechanism (9) for moving the piston (6) upward, and the collet (7) by being disposed so as to surround the collet at the upper part of the cylinder and being lifted and lowered by the lifting means (14) (15). And a collar (10) for opening and closing.

The pull stud (4) is formed of a pull stud bolt that is screwed into the lower surface of the pallet (3) and fixed in a suspended state. The lower end of the pull stud (4) is provided with an engaging head (41) projecting radially outward.
On the lower surface of the pallet (3), a female cone (11) having a first taper surface (111) obliquely downward on the inner peripheral portion is provided concentrically so as to surround the pull stud (4).

The cylinder (5) includes an upper opening recess (21) formed on the upper surface of the table (2), and a center hole (121) of the male cone (12) inserted and fixed to the upper portion of the upper opening recess (21). And is composed of.
The male cone (12) has a downward horizontal annular step (122) at a height of about one third of the lower side of the peripheral surface of the center hole (121).
The outer peripheral surface of the male cone (12) has a small diameter at the top, and the second taper surface (123) obliquely upward is in contact with the first taper surface (111) of the female cone (11) at the time of clamping. Is formed.

The piston (6) includes a disk-shaped bottom wall portion (61), an annular rising wall portion (62) that extends shortly from the outer peripheral edge of the bottom wall portion (61), and a bottom wall portion (61). And a central shaft portion (63) extending long upward from the central portion.
The rising wall (62) has an outer diameter slightly smaller than the inner diameter of the upper opening recess (21) of the table (2), and the bottom peripheral edge of the upper opening recess (21) and the male cone (12). It is located so that it can move up and down. A space between the outer surface of the rising wall portion (62) and the peripheral surface of the upper opening recess (21) is sealed with a seal member (P) such as packing.
An annular recess (64) opened upward is formed in a portion of the piston (6) between the rising wall portion (62) and the central shaft portion (63).
The central shaft portion (63) has upward horizontal annular steps (631) and (632) at two positions in the middle of the outer peripheral surface thereof. The upper part of the central shaft part (63) above the lower annular step (631) is inserted into the central hole part (121) of the male cone (12).
A head portion (633) projecting radially outward is formed at the upper end portion of the central shaft portion (63).
The upper end surface of the central shaft portion (63) has substantially the same size as the lower end surface of the pull stud (4), and is brought into pressure contact with the lower end surface of the pull stud (4) during unclamping. .

The collet (7) includes a plurality of collet division pieces (70) arranged so as to surround the upper portion of the central shaft portion (63) of the piston (6).
Each collet split piece (70) has a base portion (72) provided at the lower end thereof, and an upper annular step (631) and a head portion (633) on the outer peripheral surface of the central shaft portion (63) of the piston (6). And is urged toward the central shaft by a ring-shaped spring (13). That is, the collet (7) is urged by the ring-shaped spring (13) to open outward.
The upper end of each collet segment (70) is provided with an engaging claw (71) that is engaged with the head (41) of the pull stud (4) when the collet (7) is closed. Yes.

The clamping spring (8) is a disc spring and is interposed between the downward horizontal annular step (122) of the male cone (12) and the bottom surface of the annular recess (64) of the piston (6), and the piston ( 6) is biased downward.
The clamp spring (8) may be a spring other than a disc spring, such as a compression coil spring.

The hydraulic mechanism (9) for unclamping includes the bottom surface of the cylinder (5) (the bottom surface of the upper opening recess (21) of the table (2)) and the bottom surface of the piston (6) (the bottom surface of the bottom wall portion (61)). A first pressure oil passage (91) formed in the table (2) so as to communicate with the space between the first pressure chamber (C1) and the first pressure chamber through the first pressure oil passage (91). And a hydraulic pump (not shown) for supplying pressure oil to (C1).
Instead of the hydraulic mechanism (9), a fluid pressure mechanism using a fluid pressure other than the hydraulic pressure (for example, air pressure) may be used.

  As shown in FIG. 2, the lift stroke (S1) of the piston (6) required for clamping / unclamping is considerably shorter than that of the conventional one. In this embodiment, the upper limit of the lifting stroke (S1) of the piston (6) is defined by the upper edge of the rising wall (62) of the piston (6) coming into contact with the lower edge of the male cone (12). .

The collar (10) has a substantially cylindrical shape and has an upward horizontal annular step (101) at a height intermediate position on its outer peripheral surface.
Further, the collar (10) is formed with an annular recess (102) opened at the lower end surface thereof.
At the upper end of the inner peripheral surface of the collar (10), an annular inward projection (103) that presses the engaging claw (71) of each collet split piece (70) with the collet (7) closed from the outside. ) Is provided.
An inwardly inclined surface (104) is formed on the upper end surface of the collar (10) for guiding the engaging claw portion (71) of each collet split piece (70) when the collet (7) is opened and closed.

On the circumferential surface of the center hole (121) of the male cone (12) constituting the upper part of the cylinder (6), a downward horizontal annular step (121a) is formed at an intermediate position of the height.
A portion of the peripheral surface of the central hole (121) below the horizontal annular step (121a) is slightly spaced from the portion below the horizontal annular step (101) on the outer peripheral surface of the collar (10). The portion above the horizontal annular step (121a) of the peripheral surface of the central hole (121) is slightly above the horizontal annular step (101) on the outer peripheral surface of the collar (10) It is faced with a gap. Thereby, the collar (10) can be moved up and down along the peripheral surface of the center hole (121).
Between the portion below the horizontal annular step (121a) on the peripheral surface of the center hole (121) and the portion below the horizontal annular step (101) on the outer peripheral surface of the collar (10), and the center hole ( A seal member (P) made of packing is provided between a portion above the horizontal annular step (121a) on the peripheral surface of 121) and a portion above the horizontal annular step (101) on the outer peripheral surface of the collar (10). Is sealed by.

  The raising and lowering means for raising and lowering the collar (10) is a collar raising spring that applies an upward biasing force to the collar (10) so that the collar (10) is held at the collet closed position which is the upper limit of the raising and lowering stroke (S2). Collet open position that is the lower limit of the lifting stroke (S2) against the urging force of the collar lifting spring (14) by supplying pressure oil to (14) and the upper part of the cylinder (5) And a lowering hydraulic mechanism (15) for lowering the collar.

The illustrated collar raising spring (14) is a compression coil spring. However, this spring (14) may be constituted by other springs (for example, a disc spring).
The upper end of the spring (14) is received by the bottom surface of the annular recess (102) of the collar (10), and the lower end of the spring (14) protrudes inward from the lower end of the center hole (121) of the male cone (12). Is received by an annular spring receiving portion (121b) formed on the upper portion of the ring, and urges the collar (10) upward.

The collar lowering hydraulic mechanism (15) has a space between the upward horizontal annular step (101) of the collar (10) and the downward horizontal annular step (121a) of the peripheral surface of the center hole (121) of the male cone (12). That is, the second pressure oil channel (151) formed in the male cone (12) so as to communicate with the second pressure chamber (C2), and the second pressure chamber (C2) through the second pressure oil channel (151). And a hydraulic pump (not shown) for supplying pressure oil.
Instead of the hydraulic mechanism (15), a fluid pressure mechanism using a fluid pressure other than the hydraulic pressure (for example, air pressure) may be used.

The lifting stroke (S2) of the collar (10) necessary for opening and closing the collet (7) is as shown in FIG. 2, and is longer than the lifting stroke (S1) of the piston (6).
In the case of this embodiment, the upper limit position of the lifting stroke (S2) of the collar (10) is such that the upward horizontal annular step (101) of the collar (10) is on the peripheral surface of the central hole (121) of the male cone (12). It is defined by contacting the downward horizontal annular step (121a). Further, the upper limit position of the lifting stroke (S2) is defined by the lower end edge of the collar (10) coming into contact with the upper end edge of the spring receiving part (121b) of the center hole (121).

  Although not shown, between the table (2) and the pallet (3), a plurality of the clamping devices (1) are provided, and using these clamping devices (1), the table ( 2) The pallet (3) can be accurately positioned on the top.

When the pallet (3) is clamped on the table (2) by the clamping device (1), the following procedure is performed.
That is, first, as shown in FIG. 2, the piston (6) supplies pressure oil to the first pressure chamber (C1) through the first pressure oil passage (91), thereby increasing the upper limit of the lifting stroke (S1). Is located. The collet (7) supplies pressure oil to the second pressure chamber (C2) through the second pressure oil passage (151), thereby positioning the collar (10) at the lower limit of the lifting stroke (S2). By this, it is in the state opened to the outside.
In this state, the pull stud (4) on the lower surface side of the pallet (3) is placed on the upper end surface of the central shaft portion (63) of the piston (6), and then the hydraulic pressure in the second pressure chamber (C2). Is lowered, the collar (10) is moved to the upper limit position of the lifting stroke (S2) by the urging force of the spring (14). Along with this, the engaging claw portion (71) at the tip of each collet split piece (70) is pushed inward by the inwardly inclined surface (104) at the upper end of the collar (10), the collet (7) is closed, The engaging claw portion (71) is engaged with the head portion (41) of the pull stud (4). Thus, the pull stud (4) is gripped by the collet (7) and this state is maintained by the collar (10) as shown by the chain line in FIG.
Next, when the hydraulic pressure in the first pressure chamber (C1) is lowered, the urging force of the spring (8) moves the piston (6) to the lower limit position of the lifting stroke (S1), and accordingly the pull stud (4) The first tapered surface (111) of the female cone (11) on the pallet (3) side is pulled down through the collet (7), and the second tapered surface (123) of the male cone (12) on the table (2) side Pressure contacted.
Thus, as shown in FIG. 1, the pallet (3) is clamped on the table (2).

On the other hand, when the pallet (3) is unclamped from the table (2), it is performed as follows.
That is, as shown in FIG. 2, first, when pressure oil is supplied to the first pressure chamber (C1) through the first pressure oil passage (91) to increase the hydraulic pressure, the piston (6) is moved to the spring (8). It is moved to the upper limit position of the lifting / lowering stroke (S1) against the urging force. Along with this, the upper end surface of the central shaft portion (63) of the piston (6) is brought into pressure contact with the lower end surface of the pull stud (4), and the pull stud (4) and, in turn, the pallet (3) is moved up and down (S1). The first tapered surface (111) of the female cone (11) is separated from the second tapered surface (123) of the male cone (12).
Next, as shown in FIG. 2, when the pressure oil is supplied to the second pressure chamber (C2) through the second pressure oil channel (151) to increase the hydraulic pressure, the collar (10) is attached with the spring (14). It is moved to the lower limit position of the lifting stroke (S2) against the force. Then, the collet (7) is opened outward by the urging force of the ring-shaped spring (13), and the engaging claw portion (71) of each collet split piece (70) is the head (41) of the pull stud (4). Deviate from.
Thus, an unclamped state in which the pallet (3) can be removed from the table (2) is obtained.

In the above embodiment, the clamp device for fixing the pallet on the table has been shown. However, the present invention provides an object to be fixed other than the pallet (for example, a workpiece, a mold) on the base other than the table (for example, the work pallet). It is also possible to apply to a clamping device for fixing the.
In the clamping device of the present invention, the positional relationship between the base and the object to be fixed is not only in the case of up and down (vertical direction) as shown in the above embodiment, but also in the case of front and rear, left and right (horizontal direction), and oblique. Is applicable.
Further, in the clamping device of the present invention, the clamp driving means, the unclamp driving means, and the collar lifting / lowering means are not limited to those shown in the above embodiment, and other known driving means may be used as appropriate. Good.

(1): Clamp device
(2): Table (base)
(3): Pallet (fixed object)
(4): Pull stud
(5): Cylinder
(6): Piston
(7): Collet
(8): Clamp spring (clamp driving means)
(9): Hydraulic mechanism for unclamping (unclamping drive means)
(10): Color
(14): Spring for raising the collar (lifting means)
(15): Hydraulic mechanism for lowering the collar (lifting means)

Claims (4)

  A clamping device for fixing an object to be fixed on a base, a pull stud provided on the lower surface side of the object to be fixed, a cylinder provided on the upper surface side of the base and incorporating a piston, and an upper part of the piston A collet provided so as to be openable and closable and gripping the pull stud, a clamp driving means for moving the piston downward so that the pull stud gripped by the collet is drawn, an unclamp driving means for moving the piston upward, and a cylinder And a collar which is disposed so as to surround the collet and which is opened and closed by an elevating means to open and close the collet.   The clamp apparatus according to claim 1, wherein the clamp driving means includes a clamp spring that applies a downward biasing force to the piston.   The collar raising and lowering means for raising and lowering the collar includes a collar raising spring for applying an upward urging force to the collar so that the collar is held at the collet closed position which is the upper limit of the raising and lowering stroke. Clamping device.   The clamping device according to any one of claims 1 to 3, wherein the pull stud is pushed up by the piston during unclamping.

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