JPH045223Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a clamp device that fixes a clamp arm in a clamp position using a nut.

(Conventional technology) In order to efficiently perform machining on workpieces,
A workpiece is mounted on a workpiece set table that rotates around a predetermined axis, and tools are positioned on an axis parallel to the predetermined axis at a predetermined interval around the workpiece settable in the circumferential direction. By arranging the machine tool and moving the workpiece set table intermittently, machining such as drilling, reaming, and counterboring is performed from a direction parallel to the predetermined axis. is being done.

In addition, the workpiece set on the workpiece setting table is firmly clamped to prevent it from moving during machining, but in order to simplify this clamping mechanism as much as possible, a clamp is used to press and fix the workpiece on the workpiece setting table. The arm is swingably attached to the workpiece set table, and the tip of the clamp arm is fixed at a clamping position by a screw-type fixing mechanism using a nut. That is, a guide rod having a male thread formed on the outer periphery and extending in the direction of the predetermined axis is provided on the workpiece set table, and with the tip of the clamp arm inserted through the guide rod, a nut is screwed into the male thread. By fitting the bolts together, the workpiece is clamped to the workpiece setting table with a force corresponding to the tightening force of this nut. A nut runner disposed on the axial extension line toward the tip of the guide rod is used to thread the nut onto the male threaded portion.

The nut is removed from the guide rod when the workpiece is removed from the workpiece setting table, that is, when the clamp arm is placed in the unclamped position. For this reason, in the past, the nut removed from the guide rod was held in a nut runner. That is, while an engaging pin is provided on the inner circumferential surface of the box-shaped nut engaging portion of the nut runner so as to be freely retractable,
The engagement pin is biased in a direction protruding from the inner peripheral surface of the nut engagement portion, and an engagement hole into which the engagement pin is fitted is formed in the outer periphery of the nut. With this configuration, when the engagement pin protrudes into the engagement hole of the nut, it is prevented from falling off from the nut runner unless the nut is pulled out with great force. Of course, if the nut runner moves backward with the nut screwed into the guide rod, the locking action by the engagement pin will be released.
The nut will remain attached to the guide rod.

(Problem to be solved by the invention) However, as mentioned above, in the conventional nut runner that uses an engaging pin to hold the nut, in order to release the clamp, the nut is held by the nut runner. When the nut runner is loosened and the nut runner is moved backward, if there is resistance to pulling the nut out, for example, if the nut is screwed even slightly into the male thread, the nut will not move backward together with the nut runner, and the nut will fall. Situations like this were to occur frequently.

In this way, when the nut falls off, the worker must temporarily stop the work and try to re-hold the nut in the nut runner, resulting in inefficiency. In addition, if the worker does not notice that the nut has fallen off, subsequent work is performed without tightening the nut, which is a major cause of defective products.

The present invention was developed in consideration of the above-mentioned circumstances, and is designed to reliably prevent the nut from falling off in a clamp device that uses a nut to fix the clamp arm in the clamp position. An object of the present invention is to provide a clamping device.

(Means and operations for solving the problems) In order to achieve the above-mentioned object, the nut is basically held by the clamp arm in the present invention. Since the clamp arm swings, the nut and guide rod (externally threaded part) are automatically aligned in accordance with the swing of the clamp arm toward the clamp position. The guide rod is provided with an abutting member that is biased toward the distal end of the guide rod and comes into contact with the nut. As a result, when the clamp arm is swung toward the clamp position, the nut and the contact member come into contact with each other, and the nut is pressed and moved toward the tip of the guide rod, and the axis between the nut and the guide rod is aligned. The axes are gradually brought into alignment, and eventually the axes are completely aligned. After this, when the nut is rotated by the nut runner, the nut is screwed into (the male threaded portion of) the guide rod.

(Example) An example of the present invention will be described below based on the attached drawings.

First, the outline of the workpiece setting table to which the present invention is applied, together with the machining of the workpiece, will be explained with reference to FIGS. 1 and 2.

The work setting table 1 is rotatable around a predetermined axis O, and has a circumferential direction on one side.
It has a total of six workpiece attachment parts 2 at 60° intervals.
A workpiece is set on each workpiece mounting portion 2 using a clamping device which will be described later. Such a workpiece set table 1 is intermittently rotated every 60 degrees in a known manner, and at its rotation stop position,
Predetermined work is done. In other words, there are a total of six stations S in the circumferential direction of the work setting table 1.
1 to S6 are formed. Of these stations S1 to S6, S1 is a free position, and S
2 is for clamping (unclamping) the workpiece, S3 is for drilling,
S4 is for reaming, S5 is for tapping, and S6 is for spot boring. In order to perform each of the above-mentioned machining operations, the stations S2 to S6 are each equipped with a machining mechanism according to the machining content, and the tool axis direction is the second
As shown by the arrow in the figure, it is parallel to the rotation center O of the workpiece setting table 1. Clamping, unclamping, and counterbore at station S2 are performed from the front of workpiece setting table 1, that is, the workpiece mounting surface side (right side in FIG. 2), and station S3,
The processing in S4 and S5 is performed from the back side of the workpiece setting table 1. In this manner, a predetermined machining process is performed on the workpiece during one rotation of the workpiece setting table 1. In addition, the clamp,
Unclamping is performed by a nut runner indicated by numeral 3 in FIG.

Next, the details of the workpiece mounting portion 2 will be explained with reference to FIG. 3. First, a clamp arm 4 is attached to the workpiece set table 1 so as to be swingable about a pin 5. In this embodiment, the clamp arm 4 is composed of a main body arm 4A whose base end is attached to the workpiece set table 1 by a pin 5, and an auxiliary arm 4B which is attached to the middle part of the main body arm 4A by a bolt 6. The auxiliary arm 4B is designed to be able to swing slightly around the spherical protrusion 4a of the main body arm 4A.

Two workpiece setting holes 7 are opened in the workpiece setting table 1 in correspondence with the clamp arm 4, and the workpiece W is opened with respect to these workpiece setting holes 7.
(In the example, the knuckle arm of an automobile) is fitted. This workpiece W is attached to the workpiece setting table 1 in a predetermined posture by fitting into the workpiece setting hole 7 and using a positioning pin (not shown). When the clamp arm 4 is placed in the clamp position shown in FIG. 3, each end of the auxiliary arm 4B is
The workpiece W is firmly pressed and fixed against the workpiece setting table 1 by contacting the workpiece W. In this way, in the embodiment, two workpieces W are set for one workpiece mounting part 2, and these two
Workpieces W are clamped by one clamp arm 4. The workpiece setting table 1 is provided with a tool guide sleeve 8 so that the tool can approach the workpiece W from the back side without wobbling.

Screw-type fixing mechanism A for fixing the clamp arm 4 (main body arm 4A) at the clamp position
is constructed between the work set table 1 and the main body arm 4A. As shown in FIGS. 4 and 5, this fixing mechanism A has a guide rod 11 fixed to the workpiece setting table 1 and a nut 12 held at the tip of the main body arm 4A. The guide rod 11 extends parallel to the rotational axis O toward the side where the clamp arm 4 is located, and has a male threaded portion 11a formed on the outer periphery of the intermediate portion thereof. The tip end portion of this male threaded portion 11a has a considerably smaller diameter than the male threaded portion 11a.

On the other hand, the nut 12 has a female threaded portion 1 screwed into the male threaded portion 11a on the inner circumferential surface of the axially intermediate portion thereof.
2a, and is rotatably and slidably held in a holding hole 13 formed in the tip of the main body arm 4A. A large-diameter stopper 12b is annularly protruded from the outer periphery of the nut 12, and a holding hole 13
The inner circumferential diameter of each opening end line at the front and rear (right and left in FIGS. 3 to 5) is a locking portion 14, 15 having a smaller diameter than the outer diameter of the stopper 12b. This front locking portion 14 is integrally molded with the main body arm 4A, and
The rear locking portion 15 is constituted by a locking member fixed to the main body arm 4A. Stoppa 1
2b front and rear tip surfaces, and both front and rear locking parts 1
The contact surfaces of the stoppers 12b of 4 and 15 are respectively tapered surfaces. Further, the stopper 12b is formed relatively thinly in the axial direction of the nut 12, and has a tapered shape due to the formation of a tapered surface, causing some wobbling around the outer circumferential surface of the stopper 12b as a fulcrum. In other words, the axial center of the nut 12 can be slightly inclined with respect to the axial center of the holding hole 13. This results in
The nut 12 is prevented from coming off from the holding hole 13, and the stopper 12b is
5, the axes of the nut 12 and the holding hole 13 are aligned.

A contact member 2 is provided on the outer periphery of the guide rod 11.
1 is slidably provided. This contact member 2
1, as shown in FIG. 4, the guide pin 22 screwed into the guide pin 22 is made to protrude into the guide groove 23 formed on the outer periphery of the guide rod 11, thereby creating a stroke corresponding to the length of the guide groove 23. It is designed to be able to slide by a certain amount. Then, the abutting member 21 is connected to the guide rod 11 by the spring 24.
is biased toward the tip.

Further, the abutting member 21 has a distal end surface (FIGS. 3 to 3).
It has a contact surface 21a that can come into contact with the end surface of the nut 12 (right end surface in FIG. 5), and when the contact member 21 is at the forward stroke end position (the right stroke end position in FIGS. 3 to 5), , at the initial stage when the female threaded part 12a of the nut 12 contacts the male threaded part 11a of the guide rod 11, the contact surface 21a is the (end face of) the nut 12.
It is set so that it can come into contact with the

Next, the operation of the above configuration will be explained.

At the unclamping position where the clamp arm 4 has moved significantly to the right in FIGS. 3 to 5, the workpiece W is set on the workpiece setting table 1. After this, the clamp arm 4 is swung toward the clamp position,
Eventually, the tip of the guide rod 11 begins to be inserted into the nut 12, as shown in FIG.

As the clamp arm 4 further swings toward the clamp position, the nut 12 and the abutting member 21 come into contact with each other, and the nut 12 is gradually pressed and moved toward the tip of the guide rod 11 until it reaches the position shown in FIG. , the stopper 12b of the nut 12 is strongly abutted against the locking portion 15 on the rear side, and the axes of the guide rod 11, nut 12, and holding hole 13 are aligned.

When the clamp arm 4 further swings toward the clamping position with the axis of the guide rod 11 and the axis of the nut 12 aligned, the abutment member 21 moves back and eventually the male threaded portion 11a of the guide rod 11 and the female threaded portion 12a of the nut 12 come into contact with each other.

After this, when the nut runner 3 is advanced and its nut engaging portion 3a is engaged with the nut 12, and the nut 12 is rotated, both threaded portions 11a and 12a are screwed together, and the tightening force of the nut 12 is increased. With force according to
The workpiece W is clamped to the workpiece setting table 1 via the clamp arm 4 (see FIG. 3).

To unclamp the workpiece W, the nut 12 may be loosened by the nut runner 3, and then the clamp arm 4 may be swung toward the unclamping position. At this time, since the nut 12 is held by the clamp arm 4, the nut 12
This means that no dropout will occur.

Note that the clamp arm 4 can be easily oscillated manually or by using a cam or the like.

(Effects of the invention) As is clear from the above, the invention has the following effects:
Although the clamping force is obtained by utilizing the tightening force of the nut, it is possible to reliably prevent the nut from falling off when loosening the nut. As a result, it is possible to prevent work interruption due to the nut falling off, and it is also possible to reliably prevent a situation in which a workpiece is machined without being tightened with a nut, resulting in a defective product.

[Brief explanation of drawings]

FIG. 1 is a simplified front view showing an example of machining a workpiece using a workpiece setting table to which the present invention is applied. FIG. 2 is a plan view of FIG. 1.
FIG. 3 is a side sectional view showing one embodiment of the present invention. FIGS. 4 and 5 are side sectional views of main parts showing operating conditions different from those shown in FIG. 3. O...Rotation axis center (predetermined axis center), W...Workpiece,
A...Screw type fixing mechanism, 1...Work set table,
2...Work mounting part, 3...Nut runner, 3a
... Nut engaging part, 4 ... Clamp arm, 4a
...Body arm, 5...Pin (swing center), 11
...Guide rod, 11a...Male thread part, 12...
... Nut, 12a ... Female thread part, 12b ... Stopper, 13 ... Holding hole, 14, 15 ... Locking part,
21...Abutting member, 24...Spring.

Claims (1)

[Scope of Claim for Utility Model Registration] A workpiece set table;
a clamp arm for clamping a workpiece set on the workpiece setting table; a guide rod having an external thread formed on its outer periphery and protruding from the workpiece setting table; and a guide rod rotatably and slidably held by the clamp arm. a nut which is slidably provided on the guide rod and is biased toward the distal end side of the guide rod; an abutment member that abuts the nut in response to the swinging of the clamp arm toward the clamp position; and an abutment member that is provided on an axial extension line toward the distal end of the guide rod and drives the nut to rotate. A clamp device characterized by comprising: a nut runner for the purpose; and a nut runner for the purpose.