JPH0617833U - Pallet drop prevention device on tilt table - Google Patents

Abstract

(57) [Abstract] [Purpose] A pallet drop prevention device for a tilting table that can completely and reliably prevent falling of the pallet that may occur when the clamp device that should fix the pallet is abnormal, etc., is realized inexpensively and easily. To do. A tilt table having a clamp device 13 for fixing the pallet 3 on a rotary base 9 of the tilt table by releasably pulling the clamp pull stud 5 of the pallet 3 by using fluid pressure is used. A drop prevention pull stud 27 is provided and a ball collet type holding means 28 capable of releasably holding the fall prevention pull stud 27 by utilizing the fluid pressure and a constant holding means 28.
And a spring 40 for urging the drop prevention pull stud 27 in a direction to grip the drop stud 27. When the clamp device 13 is abnormally unclamped, the holding means 28 continues to grip the fall prevention pull stud 27 by the urging force of the spring 40.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an emergency pallet drop prevention device on a tilt table mounted on a table of a machine tool, a surface plate for measurement, or the like.

[0002]

[Prior art]

 Referring to FIG. 3 showing an example of a conventional tilt table, the tilt table 51 includes a base 56 including a pedestal portion 53 and support portions 54 provided upright on both sides of the pedestal portion 53, and an X-axis (see FIG. The tilt base 58 is supported so that it can be tilted / swirled (axis A perpendicular to 3) (A axis), and the tilt base 58 can be rotated about the Y axis perpendicular to the X axis (B axis). A pallet 63 having a T-slot 62 for fixing a work or the like on the rotation base 60 and a taper cone 65 for positioning and a fixing base. It is removably positioned and fixed via a clamp device (not shown).

The pallet 63 (the rotation base 60 and the tilt base 58) is tilted by a driving device 67 (not shown) from a horizontal position indicated by a solid line in a direction (counterclockwise in the figure) about 90 degrees. It is tilted so as to be located at (the position indicated by the two-dot chain line (a)) or at an inclined position (another position indicated by the two-dot chain line (b)) that is tilted about 20 degrees in the other direction from the horizontal position.

[0004]

[Problems to be solved by the device]

 However, in the conventional tilting table 51, the pallet 63 is lowered in an emergency such as when the pallet 63 is tilted about 90 degrees and the clamp device (not shown) is released due to a failure or the like. May fall off (fall).

The present invention has been made in view of the above circumstances, and has a simple structure that can completely and surely prevent falling of a pallet that may occur when the clamp device for fixing the pallet is abnormal. It is an object to provide a compact and pallet fall prevention device.

[0006]

[Means for Solving the Problems]

 In order to solve the above problems, a pallet fall prevention device for a tilt table according to the present invention utilizes the fluid pressure to grasp the fall prevention pull stud in conjunction with the clamping and unclamping operations of the clamping device, It is structurally characterized in that it is provided with a collet type holding means for releasably holding it and an elastic means for constantly urging the collet type holding means toward the gripping side.

[0007]

[Action]

 When the clamp device is unclamped abnormally, the collet-type holding device continues to grip the fall prevention pull stud without interlocking with the clamp device due to the urging force of the elastic device. As a result, the pallet cannot fall or drop.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 are sectional side views of essential parts of an embodiment of a pallet fall prevention device according to the present invention, and FIG. 3 is a schematic side view of a conventional tilt table. First, referring to FIG. 1, small pull studs 5 for clamping are screwed to the four corners (both sides in the figure) of the lower surface of the rectangular pallet 3, and the pull studs 5 are arranged at the center thereof. The taper bush 6 is attached in such a positional relationship that it penetrates through.

On the other hand, at a corresponding position on the upper surface of the rotation base 9, there is provided a complementary inclined outer peripheral surface that closely adheres to and engages with the inclined inner peripheral surface of the tapered bush 6 to perform a substantial pallet positioning function. A taper cone 11 is provided, and a clamp device 13 having a function of fixing the pallet 3 to the rotary base 9 by pulling (pulling) the pull stud 5 into the open state is arranged coaxially with the taper cone 11. Has been done.

The clamp device 13 has a piston 18 having a cylindrical ball collet portion 16 having a plurality of balls 15 evenly arranged in a ring shape capable of engaging with the pull stud 5 so as to move back and forth, at the tip side thereof. The piston 18 can be translationally moved up and down in a cylindrical cylinder 21 formed in the rotation base 9 by being guided by the guide block 20. The vertical movement of the piston 18 will be described in more detail. By switching the normally closed three-port valve for pneumatic pressure (hereinafter, pneumatic valve) 23, air is sent from the air source (AIR) to the so-called cylinder head side (at this time). , The hydraulic oil on the cylinder rod side is collected in the tank (T)), which causes the piston 18 to rise (FIG. 1), while the hydraulic pressure 4-port valve (hereinafter, hydraulic valve) 24 is switched to pump ( From P), the hydraulic oil is sent to the so-called cylinder rod side (at this time, the air on the cylinder head side is discharged to the atmosphere), and the piston 18 descends. The pneumatic valve 23 and the hydraulic valve 24 are controlled so as to switch from the switching position shown in FIG. 1 to that shown in FIG. 2 or vice versa.

When the piston 18 is raised as shown in FIG. 1 (left side), the height position of the ball 15 of the ball collet portion 16 at the upper end of the piston 18 and that of the inner circumferential groove 11a of the tapered cone 11 outside the same coincide with each other. Since the balls 15 can be retracted radially outward (laterally), the pull studs 5 extending in the ring of the balls 15 are not clamped, that is, are not clamped.

When the piston 18 shown in FIG. 2 (left side) is descending, the ball 15 is advanced inward by the side wall of the narrow hole of the tapered cone 11 and engages with the hooking portion of the pull stud 5, and pulls as it is. The stud 5 is pulled downward, that is, in a clamped state. By the clamp device 13 described above, the pallet 3 is releasably and reliably positioned and fixed during normal machine operation.

However, at the time of the above-mentioned clamping, the force for pulling the pull stud 5 (or the clamping force) is directly transmitted from the piston 18 via the ball 15, and the decrease in hydraulic pressure is directly related to the pulling force. Therefore, depending on the case, there is a possibility that the pull stud 5 may be released, and the pallet 3 may be dropped or dropped. That is, the pallet 3 can be clamped and unclamped (unclamped) without any problem in a normal state. However, if a failure occurs, for example, a hydraulic pressure-related problem specifically occurs and the pull stud 5 is If the pull-in is reduced or disabled, the work is continued without the pallet 3 being fixed, which is not desirable. Especially when the pallet 3 is tilted by 90 degrees, it is dropped or dropped. High risk of running out.

In order to avoid this, in the present embodiment, a large pull stud 27 for preventing the pallet from falling is attached to the central portion of the lower surface of the pallet 3 and is attached to the center position of the corresponding rotary table 9. A holding device (holding means) 28 capable of holding the pull stud 27 is provided. The holding device 28 includes a collet member 33 having a cylindrical ball collet portion 31 provided on the tip side thereof and having a plurality of balls 30 arranged in a ring shape and capable of engaging with the pull stud 27 so as to move back and forth. It basically comprises a cylindrical sleeve piston 35 movably mounted on the outside of the member 33, and a guide block 38 which is arranged outside the sleeve piston 35 and forms a cylinder 36 for driving the sleeve piston 35. The collet member 33 is integrally fixed to the rotation base 9 together with the guide block 38 so as to be pressed by the guide block 38. The sleeve piston 35 is guided by the collet member 33 and the guide block 38 and can move up and down translationally in a cylinder 36 formed in the guide block 38, but it is mounted in the cylinder 36 on the cylinder rod side. It is constantly urged downward by the compression coil spring 40.

The vertical movement of the sleeve piston 35 will be described in more detail. When the clamp device 13 is in the clamped state, air is sent from the air pressure source (AIR) to the so-called cylinder head side by switching the air pressure valve 23 (this At this time, the hydraulic oil on the cylinder rod side is collected in the tank (T), which raises the sleeve piston 35 (Fig. 1), and when the clamp device 13 is in the unclamped state, by switching the hydraulic valve. The hydraulic oil is sent from the pump (P) to the so-called cylinder rod side (at this time, the air on the cylinder head side is released into the atmosphere), and the sleeve piston 35 descends accordingly.

When the sleeve piston 35 shown in FIG. 1 (center) is raised, the height position of the ball 30 of the ball collet portion 31 at the upper end of the collet member 33 and that of the inner circumferential groove 35 a of the sleeve piston 35 outside the collet member 33. , And the balls 30 can be retracted radially outward (laterally) so that the pull studs 27 extending through the ring of balls 30 are not retained, i.e. not retained.

When the sleeve piston 35 shown in FIG. 2 (center) is lowered, the ball 30 is advanced inward by the side wall of the narrow hole portion of the sleeve piston 35 to engage or fit with the hooking portion of the pull stud 27. That is, they are in a holding state. Needless to say, the ball 30 or the ball collet portion 31 (holding means) is completely different from that in the clamp device 13 and does not pull the pull stud 27 downward, but forms a locking portion. The pull stud 27 is simply prevented from coming out therefrom.

By providing the holding device 28 described above, inconveniences such as dropping and dropping of the pallet 3 can be safely and reliably avoided even when a hydraulic problem occurs during the operation of the machine. . That is, for example, the hydraulic pressure (or hydraulic pressure supplied to the cylinder rod side) for driving the piston 18 of the clamp device 13 and the sleeve piston 35 of the holding device 28 suddenly or accidentally decreases or disappears. In this case, in the clamp device 13, the pulling force of the pull stud 5 is lost, and as a result, the clamp cannot be clamped or released. On the other hand, in the holding device 28, the side wall of the hole portion of the sleeve piston 35 interferes with the ball 30 so that the ball 30 cannot retreat outward (laterally). You cannot get out of the collet part 31. At this time, the sleeve piston 35 itself is continuously urged downward by the compression coil spring 40 regardless of the presence or absence of the hydraulic pressure.

Therefore, even if the hydraulic trouble occurs when the pallet 3 (rotational base 9) is tilted by 90 degrees, for example, even if the emergency unclamping state occurs, it does not work or is affected by it. Without holding the pulling stud 27, the pulling stud 27 can be stably and continuously held by the holding device 28, so that the pallet 3 can be effectively prevented from falling off or dropping.

Further, in this pallet drop prevention device, since the hydraulic valve and the pneumatic valve are shared with the clamp device, the number of parts can be reduced and the control can be simplified. Note that only hydraulic pressure or only pneumatic pressure may be used.

[0021]

[Effect of device]

 As described above, according to the present invention, it is possible to safely and surely prevent the pallet from coming off, which may occur when the clamp device for fixing the pallet is abnormal. Moreover, it can be realized inexpensively and easily, and is extremely practical and practical.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of essential parts of an embodiment of a pallet fall prevention device according to the present invention, showing a unclamped state.

FIG. 2 is a cross-sectional side view of an essential part of an embodiment of the pallet fall prevention device according to the present invention, showing a clamped state.

FIG. 3 is a schematic side view of a conventional tilt table.

[Explanation of symbols]

 3 ... Pallet 5, 27 ... Pull stud 6 ... Tapered bush 9 ... Rotation base 11 ... Tapered cone 13 ... Clamping device 15, 30 ... Ball 16, 31 ... Ball collet part 18 ... Piston 20, 38 ... Guide block 21, 36 ... Cylinder 23 ... Pneumatic valve 24 ... Hydraulic valve 28 ... Holding device 33 ... Collet member 35 ... Sleeve piston 40 ... Compression coil spring

Claims (1)

[Scope of utility model registration request] 1. A tilt table provided with a clamp device for fixing a pallet on a tilt table by releasably pulling a clamp pull stud provided on the bottom surface of the pallet using fluid pressure, the tilt table being provided on the bottom surface of the pallet. A drop prevention pull stud, a collet type holding means for holding the drop prevention pull stud in cooperation with the clamping and unclamping operations of the clamping device by using the fluid pressure, and a collet type holding means. A pallet fall prevention device for a tilt table, comprising elastic means for constantly urging the holding means toward the gripping side.