JPH04297849A - Pipe chuck - Google Patents

Abstract

PURPOSE:To make a core of a chuck follow the expansion of an inner diameter thereof by getting the pipe mounted on or removed from the chuck while the core thereof is mounted on or removed from the pipe to grasp an outer diameter of the pipe with outer teeth. CONSTITUTION:This pipe chuck includes a chuck frame 10A which has a wedge surface 15A on the internal surface thereof formed so that a space part 14A is formed expanding gradually from an inlet side 12A to an inner side 13A along a load shaft, a wedge-shaped outer teeth 16A which is housed in the space part 14A to grab or release a pipe TP moving to the chuck frame 10A in a direction of the load shaft X and a core 18A which is extended along the load shaft X to be inserted an end part of the pipe TP when the pipe TP is grasped with the outer teeth 26. The core 18A is made up of a wedge-shaped shaft 117c which is so formed as to is tapered gradually from the inlet side 12A of the chuck frame 10A to the inner side 13A thereof along the load shaft X and wedge-shaped inner teeth 23 which are put between the shaft 117c and an inner circumferential surface of the pipe to grasp a thick part of the pipe between the teeth and the outer teeth 16A and expanded in diameter following the decrease in the thickness of the pipe under a tensile load.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe grip which is used, for example, in a tensile testing machine and grips a pipe-shaped test piece with a wedge-shaped grip.

0002

2. Description of the Related Art FIG. 7 is a diagram showing a conventional example of this type of pipe grip. In the figure, reference numeral 1 denotes a chuck frame, in which a space 4 that gradually expands from the entrance side 2 to the back side 3 along the load axis X is formed, and a pair of wedge-shaped gripping teeth 5a, 5b ( (hereinafter also referred to as 5) is slidably housed in a wedge surface 6 in the chuck frame 1. When the chuck frame 1 is pulled up against the gripping teeth 5, the gripping teeth 5 close and clamp the pipe TP into which the core 7 has been inserted in advance, and when pulled down, they open and release the pipe TP.

0003

[Problems to be Solved by the Invention] However, such conventional pipe grips have the following problems. (1) Since the core 7 is separate from the pipe gripping tool, the core 7 must be inserted into the pipe TP in advance before being gripped. (2) The pipe TP is elongated by a tensile test, and in particular,
When the wall thickness of the pipe TP between the grip teeth 5 and the center core 7 becomes thinner, the grip teeth 5 follow the reduction in the outer diameter of the pipe TP, but the center core 7 is cylindrical and cannot follow this expansion of the inner diameter. . As a result, there is a possibility that the pipe TP cannot be gripped reliably.

An object of the present invention is to allow the core to be attached to and detached from the pipe at the same time as the pipe is attached to and detached from the gripping tool, and to allow the outer teeth to grasp the outer diameter of the pipe and the inner core to expand the inner diameter. An object of the present invention is to provide a pipe grip that follows the following.

[0005]

[Means for solving the problem] FIG. 1 showing a first embodiment
To explain in relation to
A chuck frame 10 has a wedge surface 15 formed on its inner surface so as to form a space 14 that gradually expands from the entrance side 12 to the back side 13 along the chuck frame 10. Wedge-shaped external teeth 16 move in the load axis X direction to grip and release the pipe TP, and wedge-shaped external teeth 16 extend along the load axis X and are inserted into the end of the pipe TP when the external teeth 16 grip the pipe TP. The above object is achieved by providing a core 18 that is Second
When described in conjunction with FIG. 3 showing an embodiment of claim 2,
In the invention, from the inlet side 12A to the back side 13A along the load axis.
The chuck frame 10 has a wedge surface 15A formed on its inner surface so as to form a space 14A that gradually expands.
A, wedge-shaped external teeth 16A that are housed in this space 14A and move in the load axis X direction with respect to the chuck frame 10A to grip and release the pipe TP, and integrated with the grip along the load axis X. The core 18A is inserted into the end of the pipe TP when the pipe TP is gripped by the external teeth 16A, and the core 18A is inserted along the load axis From 12A to 13A on the back side
A wedge-shaped shaft 117c that gradually becomes thinner over time, and an external tooth 16 that is held between this shaft 117c and the inner circumferential surface of the pipe.
The above object is achieved by sandwiching the thick part of the pipe between the inner teeth 23 and the wedge-shaped inner teeth 23 that expand in diameter as the pipe becomes thinner due to a tensile load.

[0006]

[Operation] In the invention of claim 1, the center core 18 extends integrally with the grip along the load axis
is inserted into the end of the pipe TP when gripping it. In the invention of claim 2, the wedge-shaped shaft 117c extends from the entrance side 12A of the chuck frame 10A to the back side 1 along the load axis X.
It gradually becomes thinner towards 3A. The wedge-shaped internal teeth 23 are sandwiched between the shaft 117c and the inner peripheral surface of the pipe, and the external teeth 16A
The thick part of the pipe TP is sandwiched between the pipes TP and TP, and when the wall thickness of the pipe TP becomes thinner due to a tensile load, the diameter expands to follow this decrease in wall thickness.

[0007] In the section of the means and effects for solving the above-mentioned problems that explains the structure of the present invention, figures of embodiments are used to make the present invention easier to understand. It is not limited to.

[0008]

[Embodiment] - First embodiment - In Figs. 1 and 2, reference numeral 10 denotes a chuck frame with a male screw 11 protruding from its upper surface, and a chuck frame 10 is provided from the inlet side 12 to the rear side along the load axis A wedge surface 15 is formed so as to form a space 14 that gradually widens toward 13. A pair of wedge-shaped external teeth 1 are provided in this space 14.
6 is slidably housed in the wedge surface 15. As shown in FIG.
A groove 16a is formed.

Reference numeral 17 denotes a grip attachment shaft that passes through the male thread 11 coaxially with the load axis X. A convex portion 17a that protrudes toward the wedge surface 15 is formed at the lower end of the grip attachment shaft. They are each loosely fitted into the formed grooves 16b. The external teeth 16 are fixed-position wedge teeth, and the wedge surface 1
When it is pulled up by 5, it abuts against the convex portion 17a and is prevented from moving any further. Grip mounting shaft 1
A cylindrical core 18 is screwed into the lower surface of 7 along the load axis X, and this core 18 can be inserted into the pipe TP when the pipe TP is held between the V grooves 16a of the pair of external teeth 16. be. Further, a flange 17b projecting outward is provided at the upper part of the grip attachment shaft 17, and the chuck frame 1
It engages with a step 19a of a cap nut 19 that is screwed onto the male screw 11 of No. 0. 20 is a handle for rotating the cap nut 19.

In order to grip the pipe TP with such a pipe grip, the cap nut 19 is loosened and the chuck frame 10 is lowered relative to the grip attachment shaft 17. 13, so they are separated from each other. Here, the pipe TP is inserted between the pair of external teeth 16 while inserting the core 18 into the pipe TP. Next, as the cap nut 19 is screwed in, the step 19a of the cap nut 19 engages with the flange 17b of the grip mounting shaft 17, so the chuck frame 10 rises relative to the grip mounting shaft 17, and the pair The external teeth 16 of are pulled up by the wedge surface 15. At this time, when the external teeth 16 come into contact with the convex portion 17a, they cannot move upward any further, and they slide between them and the wedge surface 15 of the chuck frame 10, approaching each other and clamping the pipe TP. At this time, since the core 18 is inserted into the pipe TP, the pipe TP
never collapses. Therefore, the wedge action of the external teeth 16 works effectively, and the pipe TP is gripped by the pair of external teeth 16.

[0011] In this manner, when gripping the pipe TP, the pipe TP can be inserted between the pair of external teeth 16 while inserting the core 18 extending along the load axis X into the pipe TP. The trouble of attaching and detaching the core 18 to and from the pipe TP separately from the operations of gripping and releasing the pipe is eliminated. The diameter of this core 18 can be changed as appropriate depending on the pipe diameter.

-Second Embodiment- FIGS. 3 and 4 show a second embodiment, and FIGS. 1 and 2
The same parts will be given the same reference numerals with an A or numbers in the 100s, and the explanation will focus on the differences. In both figures,
117 is the chuck frame 10A on the same axis as the load axis
A flange 117a is formed at the lower part of the grip attachment shaft, and a protrusion 117b is protruded from the left and right side surfaces of the grip attachment shaft, and the protrusion 117b is loosely fitted into the groove 16b of the pair of external teeth 16A. . Flange 11 of grip attachment shaft 117
A wedge-shaped shaft 117c is provided coaxially with the load axis X and integrally protrudes from the lower surface of 7a, and between this shaft 117c and the inner peripheral surface of the pipe, there is a gap between the pair of external teeth 16A and the pipe wall thickness. A pair of internal teeth 23 are provided to sandwich the portion. Here, axis 1
17c and the internal teeth 23 constitute a core 18A. internal teeth 23
is a non-positional wedge tooth. External tooth 16A of shaft 117c
The side surfaces 117d and 117e facing each other extend from the entrance side 12A to the back side 13A of the chuck frame 10A along the load axis X.
They gradually approach each other, and have a cross-sectional shape as shown in FIG. Side surface 2 facing the shaft 117c of the pair of internal teeth 23
3a and 23b are inclined along side surfaces 117d and 117e of the shaft 117c, and have a cross-sectional shape that fits into the shaft 117c.

To grip the pipe TP, as in the first embodiment, insert the pipe TP between the pair of external teeth 16A while inserting the core 18A into the pipe TP, and then tighten the cap nut 1.
As 9A is screwed in, the pair of external teeth 16A are pulled up by the wedge surface 15A. At this time, the pair of external teeth 16A come into contact with the convex portion 117b and then approach each other, and the pipe TP is held between the internal teeth 23 by the wedge action of the pair of external teeth 16A. Now, if you pull up this pipe grip and perform a tensile test on the pipe TP,
Due to the tensile load, the pipe TP stretches and its wall thickness becomes thinner. At this time, the external teeth 16A and the internal teeth 23 are connected to the wedge surface 15A of the chuck frame 10A and the shaft 11, respectively.
It slides along the side surfaces 117d and 117e of the pipe 7c and moves toward the thick part of the pipe TP, following the decrease in the thickness of the thick part. Therefore, even if the pipe TP becomes thinner, it is reliably held by the wedge action of the outer teeth 16A and the inner teeth 23.

-Third Embodiment- FIGS. 5 and 6 show a third embodiment, and FIGS. 1 and 2
Places similar to those in Figures 3 and 4 are marked with the same reference numerals followed by an A or a code in the 100s, and parts similar to those in Figures 3 and 4 are marked with the same numbers followed by a B or a code in the 200s. I will mainly explain the points. In both figures, 217 is a grip attachment shaft inserted into the male thread 11A of the chuck frame 10A on the same axis as the load axis
A horizontal arm 217a is provided that passes through the lower part of the frame from side to side. There are chuck frames 1 on the left and right sides of the horizontal arm 217a.
A pair of vertical arms 217b passing through 0A downward
A groove 16b of a pair of external teeth 16B and a groove 23 of a pair of internal teeth 23B are provided at the lower end of each vertical arm 217b.
A protrusion 217f is formed which is loosely fitted to the portion a. internal teeth 2
3B is a fixed position type wedge tooth, which comes into contact with the convex portion 217f when pulled up similarly to the external tooth 16B. pair of internal teeth 2
The shaft 217c, which together with 3B constitutes the center core 228, is formed integrally with the chuck frame 10A. Shaft 217c
The mutually opposing side surfaces of the internal teeth 23B both form complementary tapered planes.

In this embodiment, the shaft 217c is pulled up together with the chuck frame 10A, and both teeth 16B
, 23B are fixed position type wedge teeth, so both teeth 16B
, 23B approach in conjunction. Therefore, the pipe TP
This makes it possible to more reliably follow the decrease in wall thickness.

[0016]

According to the invention as claimed in claim 1, the core is inserted into the end of the pipe when the pipe is gripped by the external teeth. This eliminates the trouble of inserting the core into the pipe each time before gripping the pipe with the grip. Furthermore, according to the invention of claim 2, even if the wall thickness of the pipe becomes thinner due to a tensile load, the inner teeth expand in diameter to follow this decrease in wall thickness, so that the pipe can be reliably gripped during the test. Become.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing a first embodiment of a pipe grip according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a front sectional view showing a second embodiment of the pipe grip according to the present invention.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is a front sectional view showing a third embodiment of the pipe grip according to the present invention.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

FIG. 7 is a front sectional view showing a conventional pipe grip.

[Explanation of symbols]

10,10A Chuck frame 12, 12A Entrance side 13, 13A　Back side 14, 14A Space part 15,15A Wedge surface 16, 16A, 16B External teeth 18, 18A, 26B Core 117c, 217c axis 23, 23B Internal teeth

Claims (2)

[Claims] 1. A chuck frame having a wedge surface formed on the inner surface so as to form a space gradually expanding from the inlet side to the back side along the load axis; wedge-shaped external teeth that move in the load axis direction to grip and release the pipe;
A pipe gripping tool comprising: a core that extends integrally with the gripping tool along the load axis and is inserted into an end of the pipe when the pipe is gripped by the external teeth. 2. A chuck frame having a wedge surface formed on the inner surface so as to form a space gradually expanding from the entrance side to the back side along the load axis; wedge-shaped external teeth that move in the load axis direction to grip and release the pipe;
a core extending integrally with the grip along the load axis and inserted into the end of the pipe when gripping the pipe with the external teeth; The chuck frame is held between a wedge-shaped shaft that gradually becomes thinner from the inlet side to the back side, and this shaft and the inner peripheral surface of the pipe, and the thick part of the pipe is held between the external teeth and pulled. A pipe grip characterized by comprising wedge-shaped internal teeth that expand in diameter as the pipe wall thickness decreases due to load.