JPH0450990Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) The mandrel for processing circular pipes according to this invention is capable of handling a circular pipe that is a workpiece, such as when the circular pipe is crushed when plastically working the pipe. Used to prevent deformation.

(Prior Art) For example, when connecting circular pipes via a joint, it is necessary to form a male screw on the outer peripheral surface of the end of the circular pipes to be connected.

Traditionally, this type of male thread forming work was done by cutting, but in recent years, it has become possible to increase the strength of the male thread forming part by forming the male thread by drawing using rolling. ing.

In this way, when forming a male thread on the outer circumferential surface of a circular tube by rolling, the outer circumferential surface of this circular tube is strongly pressed,
This outer peripheral surface is caused to undergo plastic deformation.

For this reason, when forming a male thread by rolling, if the wall thickness of the circular tube is small, a mandrel, called a mandrel, is placed at the end of the circular tube 1 during the operation, as shown in Figure 4. Insert the support member 2 and insert the circular tube 1.
The cross section of the circular tube 1 is prevented from being deformed by the pressing force applied to the outer peripheral surface of the tube.

(Problem to be solved by the invention) However, with the conventional support member 2, it is troublesome to insert it inside the circular tube 1, which not only hinders the efficiency of the rolling operation of the circular tube 1, but also hinders the processing operation. If the inner diameter of the circular tube 1 increases as it progresses, it may not be possible to follow this and the support member 2 may wobble inside the circular tube 1, which may impede subsequent machining operations. be.

The mandrel for processing circular pipes of the present invention eliminates the above-mentioned disadvantages.

(Means for Solving the Problems) The mandrel for machining circular pipes of the present invention is divided into a plurality of parts in the circumferential direction, and in a free state, an outer mandrel that can be freely inserted into the inside of the circular pipe that is the workpiece. A hollow support piece having a diameter, and a pusher that contacts the inner peripheral surface of this support piece in a wedge-like manner and elastically expands the outer diameter of this support piece as the support piece moves in the axial direction. It is composed of a spreading member, a rod connected to the spreading member, and a driving means for driving the rod in the axial direction.

(Function) When using the circular tube processing mandrel of the present invention constructed as described above to prevent deformation of the circular tube during processing, the conical surface engagement between the pushing member and the supporting piece is released, and the supporting piece is removed. With the outside diameter of the piece reduced, this support piece is inserted into the circular pipe that is the workpiece.

Next, the pushing member is moved in the axial direction of the support piece by the driving means, the diameter of the support piece is expanded by the pushing member, and the outer peripheral surface of the support piece is aligned with the inner peripheral surface of the circular pipe that is the workpiece. bring it into contact with.

As a result, even if force is applied to the outer peripheral surface of the circular tube during machining operations, the circular tube is prevented from deforming.

Furthermore, even if the inner diameter of the circular tube expands as the machining process progresses, the supporting piece can be expanded in diameter by moving the expanding member in the axial direction of the circular tube.
The outer circumferential surface can easily follow the expansion of the circular tube, and the supporting piece will not wobble inside the circular tube.

Once the machining work is complete, spread the parts and
The support piece is moved in the opposite direction to the above case to reduce the outer diameter of the support piece, and then the support piece is extracted from the inside of the circular tube.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a sectional view showing the overall configuration, and Figure 2 showing the state in which the outer diameter of the support piece is reduced in order to be inserted into the circular pipe. 3 is a sectional view similar to FIG. 2, showing a state in which the outer diameter of the support piece is expanded in order to hold down the circular tube from the inside.

3 is a supporting piece for supporting the circular tube 1 (Figs. 2 and 3) to be processed from the inside, and by combining a plurality of dividing elements 4, 4 each having an arcuate cross section, the whole is formed into a short cylindrical shape. has been done.

Concave grooves 5 and 6 are formed on the outer circumferential surfaces of both ends of each of the dividing elements 4 and 4, respectively, and grooves 5 and 6 are formed at the base end (first to third
In the grooves 5, 5 formed on the outer peripheral surface (left end of the figure),
A protrusion 8 formed on the inner circumferential surface of the tip end of the holding cylinder 7 is engaged, and a ring spring 9 is attached to the grooves 6, 6 at the other end to bind the plurality of dividing elements 4, 4 into a cylindrical shape. This is used as support piece 3. A ring spring 9 applies elasticity to the other end of the support piece 3 to reduce its diameter. The outer diameter of the holding cylinder 7 is the same as that of the supporting piece 3.
Circular pipe 1, which is the workpiece material, is slightly larger than the outer diameter of
A stepped portion 18 is formed on the outer circumferential surface of the connecting portion of both members 7 and 3, with a step portion 18 having a diameter slightly larger than the inner diameter of the circular tube 1.

Further, sliding members 10, 10 are fixed to the inner circumferential surfaces of the distal ends of the respective dividing elements 4, 4, respectively. The inner circumferential surface of each sliding member 10, 10 is a conical concave surface 11, 11 whose diameter increases toward the tip.
The conical convex surface 13 formed on the outer circumferential surface of is in sliding contact.

The pushing and spreading member 12 is supported by the tip of the rod 15 via a deep groove type rolling bearing 14. The inner ring 16 of the rolling bearing 14 is a rod 15
The outer ring 17 is pushed out by the spreading member 12 on the outer peripheral surface of the tip end thereof.
As a result, the pushing member 12 can freely rotate in the twisting direction with respect to the rod 15, but cannot move in the axial direction (left and right directions in FIGS. 1 to 3). It is supported not to do so.

The holding cylinder 7 to which the base ends of the supporting pieces 3 are connected,
It is screwed and fixed to the outer peripheral surface of the distal end of the support tube 19.
This support tube 19 has a pair of radial bearings 20, 2.
0, and is rotatably supported inside the housing 21. The above pair of radial bearings 2
0 and 20 are respectively for the housing 21,
Slight displacement in the axial direction is possible.
Furthermore, the flange 22 formed at the base end of the support tube 19 is
It is made to face the first thrust bearing 23 attached to one radial bearing 20, and there is a sufficiently large space between the second thrust bearing 24 attached to the other radial bearing 20 and the end face of the holding cylinder 7. A first compression spring 25 having elasticity is provided. On the other hand, the second thrust bearing 24 and the housing 2
1, a second compression spring 26 having weak elasticity is provided between the first compression spring 25 and the holding cylinder 7.
A weak elasticity is imparted to the support tube 19 in the direction of protruding from the housing 21 (to the right in the drawing) through the support tube 19 .

Further, the proximal end of the rod 15 is connected to a piston 28 fitted in an air cylinder 27 (an oil cylinder may be used) attached to the housing 21. Also, between the base end side (left side in FIG. 1) end wall of the air cylinder 27 and the piston 28,
A third compression spring 29 having medium elasticity (elasticity is between the first and second compression springs 25 and 26) is provided, and unless compressed air is sent into the air cylinder 27 through the supply/discharge port 30, the piston The rod 15 is moved in the direction of protruding from the housing 21 via the rod 28.

A block 31 for detecting the position of the piston 28 is fixed to the end face of the piston 28 on the opposite side from the rod 15, and a first detection A sensor 33 and a second detection sensor 34 are attached.

Both detection sensors 33 and 34 use proximity sensors to detect the position of the piston 28 as the metal block 31 moves.
A first detection sensor 33 attached to the side surface of the support box 32 detects a relatively small displacement of the piston 28, and a second detection sensor 34 attached to the end surface of the support box 32 detects a relatively small displacement of the piston 28.
A relatively large displacement of the piston 28 is detected.

When forming a male thread by rolling, for example, on the outer circumferential surface of the end of a thin-walled metal circular tube 1 using the circular tube processing mandrel of the present invention configured as described above, the pushing-spreading member is used. 12 and the support piece 3 are disengaged from the conical surface, and with the outer diameter of the support piece 3 reduced, the support piece 3 is inserted into the circular tube 1 that is the workpiece.

That is, in this case, first, compressed air is not supplied into the air cylinder 27, and the elasticity of the third compression spring 29 pushes the spreading member 12 through the piston 28 and the rod 15 to the right in FIGS. move it towards the

As a result, the pushing member 12 moves in the direction of coming out from the inside of the support piece 3, as shown in FIG. 2, and due to the elasticity of the ring spring 9, the outer diameter of the support piece 3 is The supporting piece 3 can be inserted into the circular tube 1.
However, in this state, a stopper mechanism (not shown) is provided between both members 12 and 10 so that the spreading member 12 no longer moves to the right in the drawing with respect to the sliding member 10.

From this state, bring the circular tube 1 and the mandrel of the present invention closer to each other, insert the support piece 3 into the circular tube 1,
When the end edge of this circular tube 1 abuts against the step 18 formed at the connection part between the support piece 3 and the holding cylinder 7, the holding cylinder 7 and the support piece resist the elasticity of the second compression spring 26. 3 moves to the left in the drawing, and this movement is further transmitted to the piston 28 via the stopper mechanism and the rod 15. The left movement of the holding cylinder 7 and the supporting piece 3 stops when the seat piece 26a of the second compression spring 26 comes into contact with the step 21a of the housing 21, and when this state is reached, the position of the piston 28 is the first position. is detected by the detection sensor 33.

When the first detection sensor 33 detects the movement of the piston 28, a separately provided controller determines that the support piece 3 has been inserted to a predetermined position in the circular tube 1,
In order to increase the outer diameter of the support piece 3, compressed air is fed into the air cylinder 27 through the supply/discharge port 30,
The spreading member 12 is moved to the left in the drawing via the piston 28, the rod 15, and the rolling bearing 14. As a result, the conical convex surface 13 on the outer circumferential surface of the pushing and spreading member 12 changes from the conical concave surface 11 on the inner circumferential surface of the sliding member 10.
The supporting piece 3 with the sliding member 10 on its inner circumferential surface is expanded in diameter, and as shown in FIG. is brought into contact with the inner circumferential surface of the

As a result of the outer circumferential surface of the support piece 3 being brought into contact with the inner circumferential surface of the circular tube 1 in this way, even when force is applied to the outer circumferential surface of the circular tube 1 during machining work, the circular tube 1
is prevented from deforming. When the pushing and spreading member 12 fully enters the inside of the support piece 3 and the piston 28 moves to the left in FIG. 1, this movement is detected by the second detection sensor 34,
The controller determines that the circular tube 1 is now ready to be processed.

If a rolling die is pressed against the circular tube 1 from this state and the rolling operation is performed, the inner diameter of the circular tube 1 may expand as the processing operation progresses. During the machining operation, the piston 28 for moving the circular tube 1 is given elasticity directed to the left in the drawing by the compressed air sent into the air cylinder 27. Even when the inner diameter increases, the outer diameter of the support piece 3 automatically expands, and the outer circumferential surface of the support piece 3 remains in contact with the inner circumference of the circular pipe 1. 3 will no longer shake inside the circular tube 1.

When the circular tube 1 is rotated during machining work, the end of the circular tube 1 is fitted onto the support piece 3 and the holding cylinder 7,
Although the first compression spring 25 rotates, this rotation is not transmitted to other parts due to the presence of the rolling bearing 14 and the second thrust bearing 24.
Furthermore, when rolling a male thread on the circular tube 1, the male thread rolling roll die cannot move in the axial direction of the circular tube 1, so the circular tube 1 moves instead. In this case, the first compression spring 25 elastically contracts to allow the circular tube 1 to move in the axial direction.

When the machining work is completed, the air cylinder 27
The compressed air inside is discharged, and the elasticity of the third compression spring 29 moves the spreading member 12 to the right in the drawing via the rod 15 and the rolling bearing 14, thereby increasing the outer diameter of the support piece 3. Shrink it. As a result, the outer diameter of the support piece 3 becomes smaller than the inner diameter of the circular tube 1, so the support piece 3 is extracted from the inside of the circular tube 1.

In the case of the illustrated embodiment, the end of the circular tube 1 is tapered and the outer circumferential surface of this tapered portion is subjected to plastic working by rolling, but in the case of a straight tube, for example, slipping The member 10 is attached to the center of the dividing element 4, and the gap between the groove 5 and the protrusion 8 is increased so that the support piece 3 has a cylindrical shape with an enlarged diameter.

Note that a structure in which the inclined surfaces of the sliding member 10 and the pushing and spreading member 12 are brought into contact with each other to expand the diameter of the support piece 3 by a wedge action is disclosed in Utility Model Application No. 10232/1983 (Utility Model Application No. 10232/1983).
127336) Microfilm, JP-A-59-
Although it is similar to the device for expanding the diameter of a pipe described in Publication No. 232634, the present invention differs from the above in that it has a structure that allows the axial movement of the circular pipe when rolling a male thread on the circular pipe. This structure is different from known structures.

(Effects of the invention) The mandrel for processing circular pipes of the present invention is configured and operates as described above, so it can be easily inserted into the inside of a circular pipe, and the processing work of circular pipes can be carried out efficiently. Not only is this possible, but even if the inner diameter of the circular tube expands as the machining process progresses, it can follow this and the supporting piece will not wobble inside the circular tube, resulting in good machining. can be done. In addition, the axial movement of the circular tube, which is necessary when rolling a male thread on a circular tube, is possible by shortening the first compression spring that supports the holding cylinder, and it is possible to smoothly roll a male thread. I can do it.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a sectional view showing the overall configuration, and Figure 2 showing the state in which the outer diameter of the support piece is reduced in order to be inserted into the circular pipe. 3 is a sectional view corresponding to the right end of FIG. 1, FIG. 3 is a sectional view similar to FIG. FIG. 2 is a sectional view showing a support member conventionally used for processing circular pipes. 1... Circular pipe, 2... Supporting member, 3... Supporting piece,
4... Dividing element, 5, 6... Concave groove, 7... Holding tube, 8... Projection, 9... Ring spring, 10... Sliding member, 11... Conical concave surface, 12... Pushing and spreading member , 13... Conical convex surface, 14... Rolling bearing, 1
5... Rod, 16... Inner ring, 17... Outer ring, 1
8...Step part, 19...Support tube, 20...Radial bearing, 21...Housing, 22...Flame part, 23
...First thrust bearing, 24...Second thrust bearing, 25...First compression spring, 26...Second compression spring, 27...Air cylinder, 28...Piston, 29...No. No. 3 compression spring, 30... supply/discharge port, 31... block, 32... support box, 33...
...first detection sensor, 34...second detection sensor.

Claims (1)

[Scope of utility model registration request] (1) The outer circumferential surface has a shape that matches the inner surface of the circular pipe that is the workpiece, is rotatable, and is divided into multiple parts in the circumferential direction, one end is tied with a ring spring 9, and the other end is held. A hollow supporting piece 3 which is bound by engagement with the groove 5 of the cylinder 7 and has an outer diameter that can be freely inserted into the inner side of a circular pipe as a workpiece in a free state, and an inner periphery of this supporting piece. A pushing and spreading member 12 that contacts the surface and the inclined surface and expands the outer diameter of the supporting piece 3 as the supporting piece 3 moves in the axial direction; and a rod 15 that is connected to this pushing and spreading member so that only relative rotation is possible. , a driving means for driving this rod in the axial direction, and a holding cylinder 7 which is connected to the support piece 3 and is fitted onto the support piece 3 and which makes contact with the end face of a circular pipe which is a workpiece, is elastic so as to be movable in the axial direction. A mandrel for machining circular tubes, which is made up of a first compression spring 25 that supports the mandrel.