JPS5833061B2 - Internal shot peening device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shot peening device for processing the inner circular surface of a cylindrical shape, and is particularly suitable for use when shot peening the inner circumferential surface of a thin tube or the inner circumferential surface of a small diameter hole. It is something.

In recent years, in order to improve the fatigue limit of coil springs, etc., or to remove oxidized scale, etc. that occurs on various parts, granular steel or glass, etc., called shot, is shot at high speed onto the processed surfaces of these parts. 0.1 mvt~ on the surface
Shot peening, which forms a work-hardened layer with a depth of about 0.8 mm, has become popular as a surface treatment for metals.

Along with this, stress that has been generated due to residual stress due to cold working has recently been reduced, as seen in various types of piping for nuclear power plants that require high reliability, and in pipe members such as heat transfer tubes of heat exchangers. In order to prevent corrosion cracking and to improve the strength, hardness, etc. of these members, shot peening is increasingly performed on the inner circumferential surfaces of these members.

There are two methods for hitting the workpiece surface with shots: one that uses the centrifugal force of a drum rotating at high speed, and the other that uses the jet force of high-pressure gas from a nozzle. In particular, in order to process the inner circumferential surface of a thin tube or a small-diameter hole, an inner shot peening device that utilizes the jet force of high-pressure gas from a nozzle is used because the device can be made smaller.

However, with this type of conventional internal shot peening equipment, it is extremely difficult to maintain a constant distance between the inner circumferential surface to be processed and the nozzle that injects shot, and to maintain a constant machining time at each point on the inner circumferential surface. Because of this technique, the depth of the work-hardened layer formed on the inner circumferential surface is not uniform, and therefore the mechanical properties may vary widely depending on the location on the inner circumferential surface, resulting in poor reliability. I could only get something low.

The present invention eliminates the drawbacks of such conventional internal shot peening equipment, and aims to:
An inner shot that can keep the distance between the inner circumferential surface to be processed and the nozzle that injects the shot and the machining time at each point on the inner circumferential surface constant when performing shot pinning processing on a cylindrical inner circumferential surface. It is an object of the present invention to provide a peening device, thereby making the depth of the work-hardened layer formed on the inner circumferential surface uniform, thereby supplying an even and highly reliable product.

In order to achieve this object, the present invention has a structure in which a rotary cylinder having a nozzle protruding from one end of the telescopic tube in the axial direction for injecting a shot toward the inner circumferential surface of the workpiece is rotated relative to the telescopic tube. The end of the nozzle that is freely attached and located in the rotating tube is bent so as to be coaxial with the rotating tube, the tip of the nozzle is bent in the circumferential direction, and the other end of the telescopic tube is supplied inside. Attach an elastic body that expands with gas to partition the inner circumferential surface of the workpiece and fix the other end of the expandable tube, and connect the nozzle between the elastic body and the open end side of the workpiece. The nozzle is characterized in that the nozzle is rotated together with the rotary cylinder by the reaction of the jetting force of the gas jetted from the nozzle together with the shot at the same time as the nozzle is moved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of an inner shot peening apparatus according to the present invention used for machining the inner peripheral surface of a round hole will be described in detail below with reference to the drawings.

As shown in FIG. 1, which schematically shows the state in which the internal shot peening device according to this specific example is attached to the workpiece,
At the open end of the hole 1 of the workpiece whose work surface is the inner circumferential surface 2 of the cylindrical hole 1, a fixed ring 4 is provided with a discharge port 3 for discharging shot accumulated in the hole 1. The hole 1 is attached to the outlet 3 by evacuating the inside of the hole 1.
A shot recovery machine (not shown) is connected to the hole 1 for forcibly sucking out the shot accumulated inside the hole 1 and preventing the shot from clogging the hole 1.

A guide tube 5 that supplies high-pressure gas to the fixed ring 4 toward a shield (elastic body) 23 (described later) passes through the hole 1 so as to be slidable in the axial direction. A shot supply pipe 7 that communicates with a shot tank 6 that stores shot and supplies shot toward the nozzle 14 by high-pressure gas blown toward the nozzle 14 (described later) is fixed coaxially with the guide pipe 5. has a double tube structure.

A rack 8 is provided on the outer surface of the shot supply pipe 7 outside the guide pipe 5.
is fixedly installed, and rotation of a pinion 9 that meshes with this rack 8 causes the shot supply pipe 1 and the guide pipe 5 to move up and down, thereby moving the nozzle 14 up and down in the axial direction within the hole 1.

As shown in FIG. 3, which shows the structure of the nozzle 14, the upper end of the guide tube 5 is connected to the lower end of a telescopic tube 10 that can be expanded and contracted in the axial direction of the hole 1, and a bearing 11 is provided at this connecting portion.
, 12, the rotary tube 13 is rotatable with respect to the guide tube 5 and the telescopic tube 10, and the circumferential surface thereof has a circumferential tip so as to rotate together with the rotary tube 13 due to the reaction of the injection force of the high-pressure gas ejected together with the shot. A nozzle 14 that is bent in the direction protrudes, and a tip of the nozzle 14 protrudes forward from the tip of the nozzle 14 and is connected to a shield 23 from the guide tube 5.
A part of the high pressure gas supplied to the nozzle 1 is discharged to the outside.
A shot acceleration tube 15 for accelerating the shot injected from the rotary tube 13 is fixedly installed on the circumferential side of the rotary cylinder 13.

When the shot acceleration tube 15 is provided as in this specific example, in order to obtain the effect, the injection speed of the high pressure gas ejected from the shot acceleration tube 15 is made higher than the injection speed of the high pressure gas ejected from the nozzle 14. There is a need.

Note that the nozzle 14 is supported by an arm 16 provided between the nozzle 14 and the shot acceleration tube 15,
The end 1γ of the nozzle 14 located inside the rotating cylinder 13 is
It is bent so as to be coaxial with the rotary cylinder 13 and connected to the upper end of the shot supply pipe 7, and the shot supply pipe 7 is integrated with the rotary cylinder 13 by a bearing 18 provided at the connection part with the shot supply pipe 7. It can be rotated freely.

Furthermore, all of the above-mentioned bearings 11, 12, and 18 are shielded to prevent the high-level air inside each tube from leaking to the outside from the connecting portion.

As shown in FIG. 2a showing its detailed structure, the telescopic tube 10 is constructed by combining sleeves with different inner diameters, each having a flange-like engagement part at the upper end of the outer periphery and the lower end of the inner periphery. and the sleeve 19 located below.
Is the locking part 20a at the upper end of the outer periphery of a upward? The inner circumferential surface of the sleeve 19b located here is slidable in the axial direction, and the locking portion 2 at the upper end of the outer circumference of the lower sleeve 19a
0a and the locking part 21 at the lower end of the inner circumference of the upper sleeve 19b
b, the lower sleeve 19a is connected to the upper sleeve 19.
This prevents the lower sleeve 19-a from falling upward from the upper sleeve 19b due to the protrusion 22 provided at the upper end of the inner circumference of the sleeve after the telescopic tube 10 is assembled. Preventing it from coming out.

In this specific example, a sliding sleeve is used as the telescopic tube 10 as described above, but a bellows as shown in FIG. 2 may also be used as the telescopic tube 10.

The upper end of the telescopic tube 10 is provided with a material that expands in the radial direction of the hole 1 by the high pressure gas supplied from the guide tube 5 and comes into close contact with the inner circumferential surface 2 of the hole 1, thereby sealing the inside of the hole 1. In addition to preventing the shot from flying out, the hole 1 created by the shot recovery machine is
A shielding body 23 made of a rubber-like elastic body is provided in series to assist in vacuuming the inside and also to fix the upper end of the telescopic tube 10 within the hole 1.

To operate this specific example, the device, in which the amount of expansion and contraction of the telescopic tube 10 is adjusted in accordance with the depth of the hole 1 to be machined, is inserted deep into the hole 1, and the shield 23 is placed in a predetermined position. Once the shielding body 23 is reached, high-pressure gas is sent into the shielding body 23 from the guide tube 5 to inflate the shielding body 23, its periphery is brought into close contact with the inner peripheral surface 2 of the hole 1, and this shielding body 23 is fixed to the hole 1. Seal the inside of 1.

Next, when high-pressure gas with a lower pressure than the high-pressure gas supplied to the shield 23 is blown into the shot supply pipe 7 toward the nozzle 14 side, the shots in the shot tank 6 travel through the shot supply pipe 7 and reach the nozzle 14. It is ejected from the hole 1 toward the inner circumferential surface 2 of the hole 1, and hits the inner circumferential surface 2 of the hole 1 violently, thereby performing shot peening.

In addition, since the tip of the nozzle 14 is bent in the circumferential direction and the shot direction is oblique to the inner circumferential surface 2 of the hole 1, the injection force of the high-pressure gas ejected from the nozzle 14 together with the shot is reduced. Due to the reaction, this nozzle 14 rotates together with the rotary cylinder 13 and uniformly processes the inner circumferential surface 2 of the hole 1.

At the same time, the pinion 9 starts rotating at a constant speed, and as the guide tube 5 moves up and down, the nozzle 14 moves from the open end of the hole 1 to the shield 2.
3 or, conversely, descends from the shield 23 toward the open end of the hole 1, and the inner circumferential surface 2 of the hole 1 is uniformly shot-pinned in the depth direction of the hole 1 as well.

On the other hand, the shot that is injected from the nozzle 14 and hits the inner peripheral surface 2 of the hole 1 is extracted from the discharge port 3 of the fixed ring 4 by a shot recovery machine that vacuums the inside of the hole 1, and is collected in the shot tank 6. be done.

In this specific example, shot and high pressure gas are supplied from the same open end side, but the guide tube 5 may be directly connected to the shield 23 from the other open end, or the shot supply pipe 7 may be connected directly to the shield 23 from the other open end. The telescopic tube 10 may also be coaxially penetrated and connected to the nozzle 14 .

As described above, according to the present invention, the nozzle is automatically rotated by the jet force of the high-pressure gas jetted from the nozzle together with the shot, so that each point on the cylindrical inner circumferential surface, which is the work surface, can be processed evenly and at a constant rate. The shot peening process can be performed in a short time, and therefore the depth of the work-hardened layer formed on the inner circumferential surface can be made uniform.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing a specific example of the internal shot peening apparatus according to the present invention attached to a workpiece, and FIG. The figure is a sectional view showing the structure of another specific example of the expandable tube. Further, FIG. 3a is a sectional view showing the detailed structure of the nozzle in the above specific example, and FIG. 3a is a sectional view taken along the line A--A in FIG. 3a. In the drawing, 2 is the inner peripheral surface of the hole, 4 is a fixed ring, 5 is a guide tube, and 7
10 is a shot supply pipe, 10 is a telescopic tube, 13 is a rotating cylinder, 14
1 is a nozzle, 15 is a shot accelerator tube, and 23 is a shield.

Claims (1)

[Claims] 1. A rotating cylinder having a nozzle protruding from one end of a telescopic tube that can be freely expanded and contracted in the axial direction and which injects a shot toward the inner peripheral surface of the workpiece is rotatably attached to the telescopic tube, and the inside of the rotating cylinder is The end of the nozzle located at is bent so as to be coaxial with the rotating cylinder, and the tip of the nozzle is bent in the circumferential direction, and the other end of the telescopic tube is expanded by the gas supplied inside, and the above-mentioned covered tube is expanded. An elastic body that partitions the inner circumferential surface of the workpiece and fixes the other end of the expandable tube is attached, and the nozzle is moved between the elastic body and the open end side of the workpiece, and at the same time, the nozzle is removed. An internal shot peening apparatus characterized in that the nozzle is rotated together with the rotary cylinder by a reaction of the jetting force of the gas jetted together with the shot.