JPH0371923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus capable of forming linear or spiral grooves on the inner surface of a tubular member at high speed.

(Prior Art) In recent years, planetary ball dies and the like have been devised and researched that use balls to draw pipes and reduce frictional force during processing through rolling contact.

For example, as shown in FIG.
Cage 2 fixed to bearing 22 along the inner circumferential surface of
There is a type in which a tube 25 is passed through the ball 25 while rotating an outer ring, and the tube 25 is shrunk. There is also a type that is equipped with an outer ring 30 and a retainer 31 as well as a thrust ball bearing 32 as shown in FIG.

(Problems to be Solved by the Invention) However, in the type shown in FIG. 2, there is a problem in that the balls get loose on the raceway surface during machining, resulting in rough ripples on the tube surface after machining. Specifically, this problem is a phenomenon in which the rotation of the ball 24 is restricted in the thrust direction (rotation in the thrust direction is restricted), causing slips in the outer rings 20 and 21, causing intermittent rotation. This is because the outer ring 21 that receives the thrust load and the outer ring 20 that transmits the rotational driving force in the radial direction are connected and rotate at the same period. In addition, in the type shown in Figure 3, the surface condition is greatly improved because the ball does not vibrate in the radial direction, but the ball rotates because the thrust force during drawing is received perpendicularly on the flange surface. There was a problem that the direction was constant, local wear occurred on the ball, and processing stability was poor.

Therefore, when such a device is applied to internal groove processing, which requires particularly severe processing conditions, it is difficult to stably form not only the properties of the outer surface of the tube but also the groove shape of the inner surface, and It was impossible to process.

The present invention has been made to solve the above-mentioned problems of the prior art, and to process at high speed a tube with grooves on the inner surface, which requires particularly severe processing conditions. The object of the present invention is to provide an internal groove machining device with excellent productivity.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the internal groove processing device according to the present invention, in short, makes the inner surface of the outer race widen in the drawing direction so that the balls are formed by the thrust force during processing. While preventing the ball from being pressed against the outer race and holding the ball in an appropriate position in the radial direction with a ball holder, the ball is received on the center side of the rotational orbit at the center of the ball by a flange surface angled in the radial direction. In addition, this flange surface is rotatably supported by an angular contact bearing, so that the ball does not rotate fixedly, and by changing the contact position of the ball on the tapered surface of the outer race, the reduction can be adjusted. By integrating these parts with through bolts and attaching them to the rotating body, stable machining with a smooth surface for a long period of time is possible, and the miniaturization of the equipment enables high productivity due to high speed rotation. It is something.

The present invention will be explained in detail below based on examples.

(Embodiment) FIG. 1 shows an internal groove processing apparatus according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a tubular member to be processed, and as will be described later, a plug 2 with protrusions inserted into the inner surface is supported by a mandrel 3, and the tubular member 1 is rolled onto the plug 2 with protrusions by a ball 4, so that the inside of the pipe is Grooves are formed on the surface.

The balls 4 are held at equal intervals in the radial direction by a ball holder 6, and are formed of an outer race 5, which has a tapered end 5' on the inner surface of which the diameter on the entry side is smaller than the diameter on the exit side in the drawing direction. When the outer race 5 rotates at high speed, the balls 4 rotate and roll due to the downward friction force between the outer race 5 and the tubular member 1, forming grooves on the inner surface of the tube. ing.

Since the tubular member 1 is drawn with a force F while undergoing groove processing, a thrust force acts on the ball 4 and attempts to shift the machined part of the ball 4, so it is drawn at an angle to the radial direction. The bearing flange 7 with the flange surface 7' allows the contact point between the ball 4 and the bearing flange surface 7' to be received inside the center of the ball due to the rotation orbit of the center of the ball 4, and the bearing flange 7 is provided with an angle. It is rotatably supported by a Yulercontact bearing 8. This type of bearing can carry radial loads and unidirectional axial loads, and the angle between the balls and the inner and outer rings is 15°.
It has a contact angle of 25°, 30° or 40°. The larger the contact angle, the larger the axial load capacity, and the smaller the contact angle, the more advantageous it is to high-speed rotation. Generally, stamped steel plate cages are used, but polyamide molded cages are mainly used for high-precision bearings with a contact angle of 30° or less.

The bearing 8 is movable within the housing 10, and when the position of the bearing 8 is moved by the adjustment ring 9, the contact position of the ball 4 with the outer race via the flange 7 changes. The downward pressure of the ball 4 on the tubular member 1 can be controlled. Specifically, the adjustment ring 9 has a structure in which several rings having a certain thickness are stacked, and the thickness in the thrust direction can be adjusted by combining the number of rings. This adjustment ring 9 determines the position of the ball 4 in the thrust direction via the angular contact bearing 8 and the flange 7. Since the outer race 5 has a tapered surface 5' (the inclination is exaggerated in FIG. 1) that widens toward the end in the thrust direction, if the position in the thrust direction changes, the outer race 5 and Since the distance between the balls 4 in contact changes depending on the degree of taper, the reduction of the balls 4 with respect to the tubular member 1 can be controlled.

Note that with only the above-mentioned components, when the tubular member 1 is not inside the device, the relative positions of the ball 4, ball holder 6, etc. may shift and the ball 4 may fall off. A projection 12' is provided on the front flange 12. Here, the ball retainer 6 is for fixing the relative position of the balls 4, and has a ring-shaped structure with hole diameters slightly larger than the ball diameter at equal intervals, and is used as a bearing retainer. It is equivalent. The ball holder 6 holds the balls 4 at equal intervals when a radial force is applied to the balls 4, and when no radial force is applied (no load), the ball holder 6 holds the balls 4 at equal intervals. The ball holder 6 is tilted due to the clearance of the ball 4.
may fall off. Therefore, in order to prevent the ball 4 from falling off, the protrusion 12' is used to prevent the ball 4 from falling off.

Each of these members has a spigot structure so that their relative positions do not shift with respect to the axis, and are fixed to the rotating body 11 with through bolts 13. The rotary body 11 rotates at high speed while drawing the tubular member 1 to form grooves on the inner surface of the tube.

The rotating body 11 can be rotated at high speed by a power source (not shown), such as an electric motor or a hydraulic motor, and lubricating oil can be supplied into the processing equipment by attaching the lubricating oil to the tubular member 1 or directly into the equipment. This can also be done by spraying it on.

By the way, in the above configuration, the reason why the inner tapered surface of the outer lace is widened towards the end is that
This is to prevent breakage due to biting due to peak thrust etc. at the start of drawing, and if this tapered surface is configured at 2 to 3 degrees with respect to the drawing direction, the thickness of the adjustment ring 9 can be adjusted in 0.1 mm increments. The amount of displacement of ball 4 in the radial direction is
Fine adjustment is possible from 0.00698 to 0.01048mm. In addition, in the case of reverse end widening, that is, a taper in which the diameter on the exit side is smaller than the diameter on the entry side in the drawing direction, at the start of drawing, when the thrust load reaches its peak, the ball 4 becomes outer than the steady state. The ball 4 moves toward the exit side of the race, that is, the distance between the centers of the balls 4 becomes smaller than in the steady state, and the rolling state becomes excessive, resulting in a decrease in the thickness of the workpiece and an increase in the drawing load, leading to breakage.

In addition, the contact area and contact angle of the bearing flange 7 with the ball 4 are most important for preventing fixed rotation of the ball 4 and eliminating local wear.
When the ball contacts the bearing flange 7 inside its center rotational orbit and the bearing flange 7 has an angle of 5 to 15 degrees with respect to the radial direction, local wear of the ball is eliminated and stable machining is possible. It is something to do.

Although the method for holding the plug 2 with protrusions is not illustrated in this embodiment, floating fixation using a floating plug is preferable for processing a long material.

(effect) The device described above works as follows.

The plug 2 is held on the inner surface of the tubular member 1 to be processed at an appropriate position on the lower surface of the ball 4 by the mandrel 3, and the tubular member 1 is drawn in the direction of the arrow with a force F while rotating the rotary body 11 at high speed. The ball 4 is stably held by the three-point support of the outer race 5, the tubular member 1, and the bearing flange 7, and the bearing flange 7 contacts the ball 4 at a position closer to the center than the rotational orbit of the center of the ball 4. The ball rotation direction is shifted by the applied thrust force, and the ball 4 rotates smoothly without local wear. Therefore, the inner surface can be grooved without substantially generating ripples on the outer surface. The reason for this is as follows: The force in the thrust direction of the ball 4 is divided between the force perpendicular to the flange surface and the force in the horizontal direction because the flange surface 7 that receives it has an angle of 5 to 15 degrees with respect to the radial direction. This horizontal force becomes a force that changes the rotation (rotation) direction of the ball 4.

If the direction of rotation of the ball 4 does not deviate, the ball 4 will be rotated by the outer race 5 around one point due to the thrust load, but since the diameters of the outer race 5 and the machined part are greatly different, a slip will occur in either one (outer (The degree of slip varies depending on the race 5 and the processed material), causing local wear on the ball 4 and making it impossible to maintain machining accuracy.

However, as the direction of rotation of the ball 4 changes, the slip location changes as needed, which reduces wear. Incidentally, if the flange surface has no angle, machining accuracy can only be maintained for about one hour, but if it has an angle, machining accuracy can be maintained for about 200 hours.

(Effects of the Invention) As described in detail above, according to the present invention, the ball causes local wear due to fixed rotation, and the thrust force is received by the angular contact bearing, so the ball rotates smoothly. There is little ripple on the surface, allowing stable processing for long periods of time.
Furthermore, since the structure is simple, it can be miniaturized, the device can be rotated at high speed, the drawing speed can be significantly increased, and the productivity of internally grooved tubes can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an internal groove processing apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views showing conventional pipe processing apparatuses. 1... Tubular member, 2... Plug with protrusion, 3...
Mandrel, 4...Ball, 5...Outer race, 5'...Tapered surface, 6...Ball holder,
7... Bearing flange, 7'... Flange surface,
8... Angular contact bearing, 9...
...Adjustment ring, 10...Housing, 11...Rotating body, 12...Front flange, 12'...Protrusion,
13...Through bolt.

Claims (1)

[Claims] 1. A plug 2 with protrusions on the outer surface is inserted into the inner surface of the tubular member to be drawn, and a plurality of balls 4 whose trajectories are determined by the outer race 5 are pressed down while being held at an appropriate distance in the radial direction. In a device for forming a groove on the inner surface of the tubular member by rotating an outer race at high speed, the inner surface is widened toward the drawing direction and has a taper of 2 to 3 degrees with respect to the axis, and the tapered surface 5' and an outer race 5 for ball trajectory holding which has a function to variably lower and adjust the contact position between the ball 4 and the ball 4. and a flange surface 7' that receives the thrust force applied to the ball 4 from the tubular member during machining inside the orbit of the center of the ball. It has a bearing flange 7 which has an angle of .degree. and is rotatably supported by an angular contact bearing 8, and these outer races 5 and ball retainers 6.
and a bearing flange 7 which is integrally attached to the rotating body by through bolts 13.