JPH0632609Y2 - Grip device for rotary bending fatigue tester - Google Patents

Description

The present invention relates to a gripping device of a rotary bending fatigue tester, and more particularly to a gripping device of a rotary bending fatigue tester suitable for gripping a short test piece.

[Conventional technology]

In general, a rotary bending fatigue tester mounts both ends of a test piece on a rotating shaft of the tester, rotates the test piece, and applies a bending moment to the rotating test piece to perform a rotary bending fatigue test. A collet chuck is used as a gripping device to attach the test piece to the rotating shaft of the tester.

FIG. 2 shows a gripping device of a conventional rotary bending fatigue tester, in which a collet chuck 1 is provided with a through hole 1a having substantially the same shape as the outer diameter of the test piece 2, and an outer periphery is provided with a threaded portion 1b. A tapered portion 1c is formed. The tapered portion 1c has a gradient such that the taper portion 1c has a smaller diameter as the distance from the screw portion 1b increases. A taper hole 3a corresponding to the taper portion 1c of the collet chuck 1 is bored at the end of the rotary shaft 3 of the tester, and a screw portion 3b is formed on the outer circumference.
The tightening nut 4 has a screw portion 4a screwed into the screw portion 1b of the collet chuck 1 and a screw portion 4b screwed into the screw portion 3b of the rotary shaft 3.

Since the screw portion 1b of the collet chuck 1, the screw portion 3b of the rotary shaft 3 and the screw portions 4a and 4b of the tightening nut 4 constitute a turnbuckle, when the nut 4 is rotated, the collet chuck 1 rotates. Sliding in the direction of axis 3,
The test piece 2 is clamped and fixed by the action of a slit (not shown) formed in the axial direction.

[Problems to be solved by the device]

However, in the above-mentioned gripping device, the tightening nut 4 that has been inserted into the test piece 2 in advance is used as the screw portion 1b of the collet chuck 1.
Since the test piece is gripped by being screwed to the screw part 3b of the rotary shaft 3, the tightening required for gripping both ends of the test piece when the length of the test piece is very short. The nut stroke cannot be taken sufficiently and the backs of the tightening nuts contact each other. Therefore, the conventional gripping device cannot grip short and small test pieces, and has a problem that the test piece must be made long only for gripping.

Therefore, an object of the present invention is to provide a gripping device for a rotary bending fatigue testing machine that can reliably grip short and small test pieces.

[Means for Solving the Problems]

In order to achieve this object, the present invention is such that a taper portion having a smaller diameter toward the rear end and a screw portion following the taper portion are formed on the outer circumference, respectively, and the screw portion is located on the end side of the test piece. A collet chuck through which the test piece is inserted, a flange portion formed at the end of the rotary shaft of the rotary bending fatigue tester, and a taper hole corresponding to the taper portion of the collet chuck and the flange portion. A guide tool having a flange to be fixed on the outer circumference, the collet chuck being inserted into the taper hole, and a threaded portion of the collet chuck, and the tip end portion is the rear end surface of the guide tool during the screwing operation. And a tightening nut for tightening the collet chuck.

Further, the flange portion has a positioning recess for accommodating the tightening nut screwed into the screw portion of the collet chuck, and the guide has a step portion fitted to the peripheral surface of the positioning recess, It is desirable that the tip of the tightening nut be in contact with the end surface of the step.

[Operation] The collet chuck is inserted into the tapered portion of the guide tool, and the test piece is inserted into the collet chuck so that its end is located on the screw side. In this state, when the tightening nut is screwed into the threaded portion from the rear end of the collet chuck, the tip of the tightening nut and the rear end of the guide tool contact each other during the screwing, and the collet chuck tightens and fixes the test piece. . After that, the test piece is attached to the rotary shaft by fixing the flange of the guide tool to the flange portion.

Thus, the tightening nut is screwed from the rear end side of the collet chuck, that is, from the end side of the test piece, so that the test piece can be gripped regardless of the length of the test piece.

Further, by fitting the projection of the guide portion into the concave portion formed in the flange portion, it is possible to easily perform the centering of the rotary shaft and the test piece.

〔Example〕

Hereinafter, an embodiment of a gripping device for a rotary bending fatigue tester according to the present invention will be described with reference to FIG.

In FIG. 1, the collet chuck 5 is provided with a through hole 5a having a diameter substantially the same as the outer diameter of the grip portion of the test piece 2,
On the outer periphery of the collet chuck 5, a taper portion 5b having a smaller diameter from the front end toward the rear end is formed, and a screw portion 5c following the taper portion 5b is formed at the rear end. Of course, the collet chuck 5 has slits (not shown) for tightening the test piece 2 formed in the axial direction.

The guide tool 6 has a tapered hole 6a corresponding to the collet chuck / tapered portion 5b, and a bolt mounting hole 6c is drilled in the flange 6b on the outer circumference of the large diameter. Further, a step portion 6d is provided on the rear end surface of the guide tool 6 so as to project.

The tightening nut 7 that is screwed into the collet chuck / screw portion 5c has a tip end surface that comes into contact with the rear end surface of the step portion 6d of the guide tool. A flange 9 is formed at the tip of the rotary shaft 8 of the tester, and the flange 9 has a small hole 9a having a female thread.
And a central recess 9b having a relatively large diameter which is opened on the end face. The bolt mounting hole 6 of the guide 6 is inserted into the small hole 9a.
The bolt 10 is screwed through c. The inner diameter of the recess 9b is set to be substantially equal to the outer diameter of the end 6d of the guide 6, that is, the step 6d fits into the recess 9b. Further, the depth (depth) of the concave portion 9b is set so that the tightening nut 7 and the step portion 6d can be inserted.

Next, the operation of this embodiment will be described.

The collet chuck 5 is fitted into the tapered hole 6a of the guide tool 6, and the test piece 2 is inserted into the through hole 5a of the collet chuck 5. This insertion is performed so that the end portion of the test piece 2 is located on the screw portion 5c side of the collet chuck 5. After this, the tightening nut 7 is attached to the screw portion 5c of the collet chuck 5.
When the screw is engaged with the screw, the tip of the tightening nut 7 contacts the rear end surface of the step 6d of the guide during the screwing operation, whereby the collet chuck 5 slides toward the tightening nut 7 and the test piece 2 is attached. Tighten and fix.

After gripping the test piece 2 in this way, the guide tool 6 is attached to the flange portion 9 so that the tightening nut 7 and the step portion 6d of the guide tool 6 enter the recess 9b of the flange portion 9, and the bolt 1 is attached.
The guide tool 6 is fixed to the flange portion 9 by 0. At this time, the alignment between the central axis of the test piece 2 and the central axis of the rotary shaft 8 is achieved by the engagement between the step portion 6d and the inner peripheral surface of the recess 9b.

In the above-described embodiment, the test piece 2 and the rotary shaft 8 are centered by engaging the step portion 6d of the guide tool and the recess 9b, but such centering is not limited to this structure. It can also be achieved by other configurations.

[Effect of device]

As is clear from the above description, according to the present invention, the tightening nut is configured to be screwed into the collet chuck / screw portion from the rear end side of the collet chuck, that is, the end side of the test piece. Even a test piece can be reliably gripped. Therefore, it is not necessary to enlarge the test piece only for gripping.

Further, when the concave portion is bored in the flange portion and the step portion fitted to the concave portion is projected in the guide portion, the rotary shaft and the test piece can be easily centered.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a gripping device of a rotary bending fatigue tester according to the present invention, and FIG. 2 is a vertical sectional view showing a gripping device of a conventional rotary bending fatigue tester. 2 ... test piece, 5 ... collet chuck, 5b ... taper part, 5c ... screw part, 6 ... guide tool, 6a ... taper hole, 6b ... flange, 6d ... step part, 7 ... Tightening nut, 8 ... Rotating shaft, 9 ... Flange, 9b ... Recess.

Claims (2)

[Scope of utility model registration request] 1. A taper portion having a smaller diameter toward the rear end and a threaded portion following the taper portion are formed on the outer circumference, respectively, and the test piece is inserted so that the threaded portion is located on the end side of the test piece. A collet chuck, a flange portion formed at the end of the rotary shaft of the rotary bending fatigue tester, and a flange fixed to the flange portion and having a tapered hole corresponding to the tapered portion of the collet chuck on the outer periphery. A guide tool in which the collet chuck is inserted into the tapered hole and a screw part of the collet chuck are screwed, and the tip end abuts the rear end surface of the guide tool during the screwing operation, whereby the collet A gripping device for a rotary bending fatigue tester, comprising a tightening nut for tightening a chuck. 2. The flange portion has a positioning recess for accommodating the tightening nut screwed into the threaded portion of the collet chuck, and the guide has a stepped portion fitted to the peripheral surface of the positioning recess. The gripping device for a rotary bending fatigue tester according to claim 1, wherein a tip end portion of the tightening nut abuts an end surface of the step portion.