JPH07124675A - Thread rolling machine - Google Patents

Abstract

PURPOSE:To provide a thread rolling machine reduced in the dispersion of working precision and contributing the quality stability by eliminating uneven rotation between a rack and the work. CONSTITUTION:A thread rolling machine is provided with one pair of ball screws 7 supported by a frame, one pair of sliders 12 moving in parallel by rotation of each engaged ball screw 7, one pair of racks 6 fitted to each slider 12 and a servo-motor rotate-driving the ball screw 7. Both ends of the work are held by a center pin 3 and a drive center 4 rotating integrally with the work 2 and further, a motor 5 for speed control is driven preceding to start of the thread rolling by engaging the rack 6 with the work 2 by fitting the motor 5 for speed control rotate-driving the driving center 4, and the work 2 is rotated in accordance with the working speed of the rack 6 for this work 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling machine for manufacturing splines, screws and the like, and more particularly to a rolling machine for eliminating uneven rotation of a work at the start of rolling.

[0002]

2. Description of the Related Art Rolling is a method in which a rack, which is a work to be processed, is rolled while being pressed so that the reverse shape of the rack surface is transferred to the work and plastically deformed. Rolled splines, etc., have a continuous rolling structure that forms streamlines (fibers), and during rolling, the valleys are particularly stress-concentrated and work-hardened significantly, and the thread surface is smooth. Has become. For these reasons, rolled products are superior in mechanical strength and the like to cutting splines, and for processing spline shafts, etc.
Rolling machines have been used exclusively.

A rolling machine of this type has a structure in which a servomotor for rotating a ball screw is used in place of a hydraulic cylinder, and a pair of racks are moved in opposite directions to perform rolling. Proposed (Actual fair 3-18023)
JP-A-63-235036, etc.). Here, the center pins 3 and 3 support the centers of both sides of the work 2, and the pair of racks 6 and 6 are moved in opposite directions while being synchronized by the servomotor 16 via the ball screws 7 and 7. , The work 2 was rolled due to the friction between the rack 6 and the work 2 (FIG. 4, FIG.
Figure 5).

[0004]

The conventional rolling machine driven by the servomotor 16 has the following problems. The work 2 is supported by the center pins 3 and 3 at the centers of both ends of the work, but is in a stationary state until the rack 6 bites, and depends only on the friction generated between the rack 6 and the work 2. Since the workpiece 2 is rotated, the workpiece 2 becomes unstable when the workpiece 2 shifts from the stationary state to the rotating state. As a result, rack 6
And the work 2 slipped, causing uneven rotation of the work 2.

However, although the upper and lower racks 6 and 6 are perfectly synchronized by the servomotor 16, no consideration is given to the slip between the rack 6 and the work 2 as described above. Therefore, work 2
Due to the above-mentioned uneven rotation, it was not possible to maintain an appropriate feed speed, resulting in variations in processing accuracy. As a countermeasure against this, the sloped portion A of the rack 6 is processed by blast shot or the like to improve the biting friction and to improve the rack 6 and the work 2.
Although attempts have been made to improve the frictional force with the above, the above problems have not been solved yet.

The present invention solves the above problems, and an object of the present invention is to provide a rolling machine that eliminates uneven rotation between a rack and a work, reduces variations in processing accuracy, and contributes to stable quality. To do.

[0007]

SUMMARY OF THE INVENTION A rolling machine according to the present invention comprises a pair of ball screws rotatably supported by a frame, and a pair of sliders that mesh with the ball screws and move in parallel by the rotation of the ball screws. And a pair of racks mounted on each slider, and a servomotor that rotationally drives the ball screw so as to move the pair of racks in opposite directions, and rolls the work inserted between the racks. In the rolling machine for imprinting the blade shape of this rack, at least one of the center pins that rotatably clamps the work at both ends is replaced with a drive center that rotates integrally with the work. By attaching a speed control motor that drives the rotation of the machine, the speed control motor is driven before the rack engages with the work and starts rolling. Characterized in that as allowed to rotate the workpiece in accordance with the processing speed of the rack relative to the workpiece.

Here, the "drive center" refers to one that plays the role of a rotating center for a spindle that rotates integrally with a workpiece as a workpiece, and its shape does not matter.

[0009]

According to the rolling machine of the present invention, before the rack is engaged with the work and the rolling is started, the speed control motor is driven to adjust the work to the moving speed of the rack through the drive center. Rotate. Therefore, it is not necessary to rely on the friction of the rack to rotate the work, and the rotation of the work is uniform. By the rotation of the work, slippage between the rack and the work is suppressed, and a sudden load change at the rolling start time is alleviated.

[0010]

EXAMPLES The present invention will be described in detail below based on examples.
1 to 3 show an embodiment of a rolling machine according to the present invention.
1 is a front view of the rolling machine, FIG. 2 is a sectional view taken along line XX of FIG.
FIG. 3 shows an enlarged view around the work.

Reference numeral 1 is a frame of a rolling machine, which is manufactured by casting. As shown in FIG. 2, a work 2 which is a workpiece is rotatably held in the center of the frame 1 with its both ends sandwiched by a center pin 3 and a drive center 4 of a tailstock, as shown in FIG. . The drive center 4 has a locking claw 41 at its tip, is engaged with the work 2 and rotates integrally with the work 2. Locking claw 41
Are arranged at three positions at 120 degree intervals so as to surround the shaft core 42 (FIG. 3).

Reference numeral 5 is a speed control motor connected to the drive center 4 (FIG. 2). Here, a servo motor directly connected to the drive center 4 is used.
The speed control motor 5 is a rotation-dedicated motor, and the rotation of the motor is controlled in synchronization so that the moving speed of the rack 6 described later and the outer peripheral speed of the workpiece 2 become the same speed. Specifically, by grasping the feed speed of the rack 6,
Open control is performed so that the peripheral speed of the work 2 and the peripheral speed of the work 2 are the same. Alternatively, feedback control may be used. The speed control motor 5 is driven to rotate the work 2 by the time when the rack 6 meshes with the work 2 and starts rolling.

Reference numeral 7 is a pair of ball screws 7 arranged in parallel at positions equidistant from the work 2, and the ball screws 7 are rotatably supported by bearings 8. The ball screw 7 is provided with a sliding body 9 which holds a large number of steel balls in a retainer and moves along the ball screw 7 by the rotation of the ball screw 7. A connecting member 10 is fixedly attached to the sliding body 9.

On the other hand, a pair of dovetail-shaped guide bars 11, 11 are fixed to the frame 1 in parallel with the ball screw 7 (FIG. 1). Further, a pair of sliders 12, 12 which are fitted in the dovetail grooves of the respective guide bars 11 and slidable are provided. A rack holder 13 is fixed to each slider 12. The racks 6 and 6 are detachably attached to the rack holders 13 and 13,
It is attached to the slider 12. The pair of racks 6, 6
It is located in a point object with respect to the center of the work 2. On the surface of the rack 6, a predetermined blade shape that is rolled into the work 2 is formed. Here, since the slider 12 is screw-connected to the connecting member 10, the rack 6 and the rack holder 1
3, the slider 12, the connecting member 10 and the sliding body 9 move integrally with the ball screw 7.

Reference numerals 14 and 14 denote toothed pulleys fixed to one side of the ball screws 7 and 7 supported by the bearing 8.
Brackets 15 and 15 are provided on the side surface of the frame 1 on the toothed pulley 14 side, and a pair of servo motors 16 and 16 are attached to the bracket 15. The toothed pulley 17 is also fixed to the shaft of the servomotor 16, and by rotating the toothed belt 18 between the toothed pulleys 14 and 17, the rotation of the servomotor 16 is accurately transmitted to the ball screw 7. When the servo motors 16 and 16 are activated, the ball screw 7 rotates and the pair of racks 6 and 6 move in opposite directions. The servomotor 16 has a torque sufficient for the rack 6 to provide a thrust force equal to or greater than the thrust force required to roll-form the workpiece 2.

An encoder 19 is attached to the servo motor 16, and an electric signal detected by the encoder 19 is fed back to an NC device (not shown) connected to each servo motor 16. Then, the electric signal subjected to the comparison processing inside the NC device controls the servo motor 16, and the pair of sliders 12 and 12 feeds the feed speed thereof.
The mutual positional relationship between the slider 12 and the center of the center pin 3 is synchronized. On the other hand, the electric signal is also sent to the speed control motor 5 so that the machining speed of the rack 6 and the peripheral speed of the work 2 are synchronized before the rack 6 meshes with the work 2. Therefore, the speed control motor 5 is driven.

In the rolling machine thus constructed, when the rack 6 and the work 2 are engaged with each other to start rolling, the speed control motor 5 causes the work 2 to rotate in accordance with the machining speed of the rack 6. The rotation irregularity of 2 itself disappeared, the instability as in the past was eliminated, and the processing speed became stable. Further, since the peripheral speed of the work 2 becomes the same as the moving speed of the rack 6, the load applied to the rack 6 at the start of rolling is reduced, and the life of the rack 6 is extended.
Further, since the rotation of the work 2 does not depend on the friction with the rack 6, shot blasting of the rack 6 is not necessary, which contributes to cost reduction.

The present invention is not limited to those shown in the above embodiment, but various modifications can be made within the scope of the present invention depending on the purpose and application. For example, the speed control motor 5 may be a servo motor, a spindle motor (spindle motor used in a lathe or the like), or any other general-purpose motor provided that it has a function to match the processing speed of the rack 6. . Further, the drive center 4 and the speed control motor 5 can be used not only in the case of being directly connected but also those having a transmission mechanism such as a toothed pulley and a toothed belt. The rotation of the work 2 by the speed control motor 5 includes not only rotation of the work 6 in synchronization with the processing speed of the rack 6, but also rotation of the work following the speed.

[0019]

As described above, the rolling machine according to the present invention is
There is little variation in the machining accuracy of the work piece, it exerts its power for stable quality, and it also contributes to reducing the load on the tool and extending the life of the rack, which is very effective.

[Brief description of drawings]

FIG. 1 is a front view of a rolling machine according to an embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is an enlarged side view of the periphery of the work in FIG.

FIG. 4 is a schematic explanatory diagram of a conventional technique.

5 is an enlarged side view around the work in FIG. 4. FIG.

FIG. 6 is an enlarged view of the work of FIG.

[Explanation of symbols]

 1 frame 2 work 3 center pin 4 drive center 5 speed control motor 6 rack 7 ball screw 12 slider 16 servo motor

Claims (1)

[Claims] 1. A pair of ball screws that are rotatably supported by a frame, a pair of sliders that mesh with the ball screws and move in parallel by the rotation of the ball screws, and a pair of racks attached to the sliders. A rolling machine that has a servomotor that rotationally drives the ball screw so as to move the pair of racks in opposite directions, rolls a work inserted between the racks, and imprints a blade shape of the racks. By replacing at least one of the center pins that rotatably clamp the work at both ends with a drive center that rotates integrally with the work, and further by mounting a speed control motor that drives the drive center to rotate. , Before the rack is engaged with the work and starts rolling.
A rolling machine characterized in that the speed control motor is driven to rotate the work according to the processing speed of the rack for the work.