JPH05164210A - Manufacture of ball screw - Google Patents

Abstract

PURPOSE:To easily obtain a ball screw which enables the feeding action with high accuracy by reducing the backlash. CONSTITUTION:When a ball screw is manufactured by screwing one pair of nut bodies 10, 20 into a screw shaft 2 and connecting these, preloaded groove parts 16, 26 are first formed on the outer circumferential part of the nut bodies 10, 20. Then, a pair of the nut bodies 10, 20 are brought into contact with each other on the screw shaft 2, and the connection phase is adjusted. Furthermore, the preloaded groove parts 16, 26 of a pair of the nut bodies are embedded with a resin material and fixed thereby so that the preloaded groove parts may be connected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ball screw which can easily apply a proper value of preload.

[0002]

2. Description of the Related Art Conventionally, ball screws are often used in sliding parts of industrial equipment such as machine tools and industrial robots in order to ensure smooth and precise operation even under a large load. ..

The conventional structure of this ball screw is shown in FIGS.
Prior art will be described with reference to these figures. Here, FIG. 5 is a front view showing a state in which a conventional ball screw is attached to a device, FIG. 6 is an exploded perspective view of the conventional ball screw, and FIG. 7 is a view showing the return tube implanting portion of FIG. FIG.

That is, in the conventional ball screw, as shown in these drawings, a large number of balls 3 are interposed between the screw shaft 2 and a pair of nut bodies 30 and 40 fitted to the screw shaft 2. The rotation of the ball 3 causes the nut body 30,
The unit 40 can be smoothly moved in the left-right direction in FIG. The return tubes 11 and 21 are fixed to the nut bodies 30 and 40 by the bolts 13 and 23 via the return tube retainers 32 and 42 so that the rotated balls 3 circulate in the nut body 3. The balls 11 are appropriately moved while being rotated by the tubes 11 and 21, and are circulated.

Further, when manufacturing this ball screw, a preload, which is a preload, is applied in order to eliminate backlash, enhance rigidity, and perform highly accurate positioning. The value of this preload is finely adjusted by grinding the thickness of the adjustment collar 4 so as to be sandwiched between the nut body 30 and the nut body 40, and the nut body 3
By fitting the key 8 into the key grooves 36, 46, 6 formed in the 0, 40 and the adjusting collar 4, respectively, and restricting the relative rotation between the pair of nut bodies 30, 40,
It is being adjusted and set.

[0006]

The preload value of the above-mentioned ball screw is obtained from JISB1192 by the following equation (1). In this equation, T represents preload torque (Nm), β represents lead angle (deg), Fa represents preload (preload) (N), L represents lead (mm),
As the measurement conditions, lubricating oil is used, and the rotation speed is 100 rpm
And

[0007]

## EQU1 ## T = 0.05 × (tan β) ^−0.5 × (Fa · L / 2π) × 10 ⁻³ (N · m)

That is, the adjusting collar 4 is processed into a trial thickness, assembled, torque is measured, and if the calculated value of the equation 1 is too large, the thickness of the adjusting collar 4 is driven to reduce the preload Fa. Similarly, if it is too small, the adjustment collar 4 is replaced with a thicker one to increase the preload Fa.

By changing the thickness of the adjusting collar 4 by 2 to 5 μm, the preload value changes by 10 N · m. Therefore, the above-mentioned current adjustment processing by the thickness of the adjustment collar 4 is difficult. Further, when the adjustment collar 4 is inserted between the nut body 30 and the nut body 40, a wedge is inserted between these to spread the adjustment collar. At this time, a load larger than the preload is applied to the screw shaft 2,
The screw shaft 2 may be damaged. Furthermore, adjustment color 4
When it was repeatedly taken in and out several times, dust had entered the abutting surface and the preload value was sometimes deviated.

[0010]

A method of manufacturing a ball screw according to the present invention is a method of manufacturing a ball screw in which a preload is applied by joining a pair of nut bodies screwed to a screw shaft, respectively. After adjusting the joining phase by abutting between the main bodies, the grooves formed in each of the nut main bodies are filled with a resin material so as to communicate with each other when the nut main bodies are in contact with each other, and the nut main bodies are fixed to each other. It is characterized by that.

[0011]

A ball screw having a preload is manufactured by joining a pair of nut main bodies on a screw shaft while applying a mutual force along the rotation direction of the nut main bodies. At this time, while the pair of nut bodies are in contact with each other, the pair of nut bodies are relatively rotated to adjust the preload, and then the resin material is injected into the groove portions of the respective nut bodies, so that the preload is kept constant by the resin material. These nut bodies are fixed to each other while maintaining the value of.

[0012]

1 to 4 show a ball screw manufactured by a method of manufacturing a ball screw according to an embodiment of the present invention, and this embodiment will be described based on these drawings. The same members as those described in the related art will be designated by the same reference numerals.

FIG. 1 is a front view of the ball screw, FIG. 2 is an exploded perspective view of the ball screw, and FIG. 3 is a sectional view of the ball screw. As shown in these drawings, a pair of circular nut-shaped nut bodies 10 each having a screw shaft 2 having a spiral thread groove 2a formed on its inner peripheral surface with a thread groove 5a facing the thread groove 2a, 20 is fitted. A plurality of balls 3 are interposed between the screw grooves 2a and 5a so as to be guided by the screw grooves 2a and 5a, and the balls 3 form the screw shaft 2 and the pair of nut bodies 10, 20.
The friction with the nut 5 formed by joining is reduced. On the other hand, the nut body 10 on the left side in FIG. 1 has a flange portion 10a, and the nut 5 is fixed by screwing between the flange 10a and the mounting seat 1 which is a part of a table of a machine tool or the like. It is fixed to the mounting seat 1.

In each of the pair of nut bodies 10 and 20, inside the nut bodies 10 and 20, return tubes 11 and 21, which are U-shaped metal tubes, intersect with the thread groove 2a. It is installed in. Therefore, the return tubes 11 and 21 jump over the single thread groove 2a to connect the two thread grooves 2a, and the balls 3 pass through the return tubes 11 and 21 to circulate the balls 3. ..

That is, each nut body 10, 20 has
Two insertion groove portions 14 and 24 are formed by processing, and the return tube 11 and the return tube 11 are formed in the insertion groove portions 14 and 24, respectively.
21 is buried. Then, in order to press the return tubes 11 and 21 and fix them to the nut bodies 10 and 20, the return tube retainers 12 and 22 are fixed to the fixing groove portions 15 and 25 formed on the outer peripheral surfaces of the nut bodies 10 and 20, respectively.
And the bolts 13 and 23 are screwed into the nut bodies 10 and 20 via the return tube retainers 12 and 22.

On the other hand, as shown in FIGS. 2 and 4, on the outer peripheral surface of each nut body 10, 20, each nut body 10,
20 along the contact surface of the preload groove 16, 2 for preload
6 is formed, and when the nut bodies 10 and 20 are brought into contact with each other, the preload groove portions 16 and 26 are positioned to communicate with each other.

Next, the assembling work of the ball screw of this embodiment will be described.

First, the screw shaft 2 is attached to the nut bodies 10 and 20.
And the ball 3 is filled between the thread grooves 2a and 5a between the screw shaft 2 and the nut bodies 10 and 20.
After this, the return tube 1 is inserted into the nut bodies 10 and 20.
1, 21 are installed, and the return tube retainer 1
2, 22 are fixed to the nut bodies 10, 20 with bolts 13, 23. Then, the molten resin material 40 is injected into the insertion groove portions 14 and 24 and the fixing groove portions 15 and 25 of the nut bodies 10 and 20 to be cured, and the return tube 1
The return tube retainers 12 and 22 are embedded together with the valves 1 and 21 to prevent rattling and vibration of these.

On the other hand, each nut body 10, 2
0 is moved along the screw shaft 2 and brought into contact therewith, and is further pressed with a force f ₁ by a pinching tool (not shown) so that Δ parts A shown in FIG.
The preload is applied by changing the joining phase, which is the phase in the rotational direction between the nut bodies 10 and 20. This work is called load-up work.

On the contrary, when lowering the preload,
The force f _{2 is applied} by the pinching tool so that parts B approach each other.
Press to change the mutual phase of the nut bodies 10 and 20 in the opposite direction to the above to reduce the preload. This work is called free work.

After the preload adjustment is completed by performing such an operation, the resin material 30 is injected into the preload groove portions 16 and 26, hardened, and filled. Therefore, the resin material 30 fixedly connects and bonds the pair of nut bodies 10 and 20.

A comparison between the adjustment of the thickness of the adjusting collar 4 in the prior art and this embodiment is as follows. That is, in order to apply the same preload that changes the thickness of the adjusting collar 4 by 2 to 5 μm with the ball screw having the lead of 10 mm, the phase in the rotation direction of 7.2 to 18.0 deg obtained by the following formula 2 is obtained. It is necessary to adjust the angle θ.

[0023]

## EQU2 ## θ deg = 360 deg × (2-5) μm × 10 mm × 1 mm / 1000 μm = 7.2-18.0 deg

Therefore, the adjustment of the phase angle θ is comparatively large, and as a result, the adjustment becomes easy.
Since 6 and 26 are provided and adjustment is performed with the sandwiching tool, the adjustment can be further facilitated.

[0025]

According to the method of manufacturing a ball screw of the present invention, after adjusting the preload using the groove portions formed in the pair of nut bodies, the resin material is injected into the groove portions to fix the nut body. As a result, it becomes possible to easily and quickly adjust and set the preload on the torque measuring machine. Further, since the resin material is injected into the groove and hardened, the joint phase between the nut bodies is sufficiently maintained even when the ball screw is used. Further, it has an effect of reducing the number of parts as compared with the conventional ball screw.

[Brief description of drawings]

FIG. 1 is a front view showing a state in which a ball screw manufactured by a ball screw manufacturing method according to an embodiment of the present invention is attached to a device.

FIG. 2 is a partially cutaway exploded perspective view of a ball screw manufactured by a method of manufacturing a ball screw according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a return tube implanting portion of a ball screw manufactured by a ball screw manufacturing method according to an embodiment of the present invention.

FIG. 4 is a diagram showing a preload adjusting method in the method of manufacturing the ball screw according to the embodiment of the present invention.

FIG. 5 is a front view showing a state where a ball screw manufactured by a ball screw manufacturing method according to a conventional technique is attached to a device.

FIG. 6 is a partially cutaway exploded perspective view of a ball screw manufactured by a ball screw manufacturing method according to a conventional technique.

FIG. 7 is a cross-sectional view of a return tube implanting portion of a ball screw manufactured by a ball screw manufacturing method according to a conventional technique.

[Explanation of symbols]

 1 Mounting Seat 2 Screw Shaft 3 Ball 4 Adjustment Collar 5 Nut 10, 20, 30, 40 Nut Main Body 11, 21 Return Tube 14, 24 Insertion Groove 16, 26 Preload Groove 30, 40 Resin Material

Claims (1)

[Claims] 1. A method of manufacturing a ball screw for applying a preload by joining a pair of nut bodies, each of which is screwed to a screw shaft, wherein the nut bodies are brought into contact with each other to adjust a joining phase. A method for manufacturing a ball screw, wherein grooves formed in each of the nut bodies are filled with a resin material so as to communicate with each other when the nut bodies are in contact with each other, and the nut bodies are fixed to each other.