JPH0361751A - Backlash removing method for involute worm driving mechanism and device - Google Patents

Abstract

PURPOSE:To facilitate machining, improve precision, and surely remove backlash by using a flat gear assembled with split wheel sections divided into two in the teeth width direction for a wheel engaged with an involute worm. CONSTITUTION:A worm wheel 14 is constituted of split wheel sections 14a and 14b divided into two from the center in the teeth width direction, and the wheel section 14b is coupled with the boss section 16 of 14a and fixed with a screw 17. A pin 31 screwed and fixed on one wheel section 14a and a pin 30 screwed and fixed on the other wheel section 14b are provided, head sections 32 and 33 are coupled with both pins 31 and 30 respectively, and a turnbuckle 34 cut with the right and left opposite threads on both ends is screwed in screw holes provided on both head sections 32 and 33 face to face respectively. After an involute worm 15 and the wheel 14 are installed at the preset positions, the turnbuckle 34 is rotated and adjusted, thus the interval between pins 30 and 31 is adjusted, wheels 14a and 14b are rotated around the shaft of the wheel 14, and backlash can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for eliminating backlash in an involute worm drive mechanism.

(Conventional technology) There are various types of reduction mechanisms that use gears, but
In particular, when attempting to obtain a large reduction ratio between two orthogonal axes that are not on the same plane, a worm reduction gear is used.

FIG. 10 is an example. In the case of such a reducer consisting of the worm 1 and the spear wheel 2, processing is relatively easy if there is a worm hob of the same shape as the worm 1, but since it cannot be manufactured by grinding, In order to obtain high-precision products, a high-precision worm hob is required as well as precision control of the processing machine. Moreover, this type of reducer requires a fairly large pack lash, so when using a conventional worm reducer to servo drive an NC machine, etc., there is a problem that the loop gain cannot be increased. did.

In order to solve these problems, various methods of removing backlash have been attempted in the prior art, as described below.

FIG. 11 shows a method in which two worms 3 and 4 are engaged with the worm wheel 2 from both sides, and the left and right tooth surfaces are driven to eliminate backlash.

Figure 12 shows the worm 1 with different leads jl+t2 (
t+ ≠ t2) [double lead], this warm 1
This method reduces backlash by moving the worm wheel in the axial direction with respect to the worm wheel.

Furthermore, FIG. 13 shows that the worm 1 is divided into two parts, one worm part 5 is provided with a threaded part 7, and the other worm part 6 is screwed into this, and this is engaged with the worm wheel 2. By rotating one of the two worm parts 6 relative to the other worm part 5, the distance between the two worm parts 5 and 6 can be adjusted, and the tooth surface of the worm wheel 2 can be moved back and forth. This is a method to reduce the backlash by sandwiching it between the two sides.

However, all of the above-mentioned backlash removal mechanisms are not easy to work with and have various structural limitations, so there is a problem in that it is difficult to sufficiently reduce backlash.

(Problems to be Solved by the Invention) As mentioned above, the prior art has various problems in terms of workmanship and accuracy. The present invention uses an involute worm as the worm, and a mating wheel that meshes with the worm.
It uses a spur gear that combines two divided wheel parts in the tooth width direction, and by rotating these gears relative to each other around the wheel axis, backlash can be removed, making it easy to work. Moreover, it is an object of the present invention to provide a practically useful method and device for removing backlash, which is highly accurate and capable of reliably removing backlash.

[Structure of the invention]

(Means for Solving the Problems) The method for removing backlash in an involute worm drive mechanism of the present invention includes the following means to achieve the above object.

An involute worm is used as the worm, and the other worm wheel that meshes with the spur gear is divided into two in the tooth width direction, and these are rotated relatively around the wheel axis to create a phase difference between the two divided wheel parts. to remove backlash.

Further, the backlash removal device for an involute worm drive mechanism of the present invention is comprised of the following means to achieve the above object.

The mating wheel that meshes with the involute worm is constructed by combining spur gears divided into two in the tooth width direction.

An operating member is fixed to each of these split wheel parts,
An adjusting member that can freely adjust the distance between these two fixed operating members is connected to the two fixed operating members, and by adjusting the adjusting member, the two movable members are adjusted relative to each other. , thereby changing the spacing between them, so that the split wheel portions rotate relative to each other around the wheel axis.

thing.

(Function) When there is backlash in the engagement between the wheel and the involute worm, which are divided into two in the tooth width direction, when the combined divided wheel parts are rotated relatively around the wheel axis, the two divisions occur. Eliminates backlash by creating a phase difference between the teeth of the wheel.

When the adjusting member of the backlash eliminator is adjusted, the two actuating members move in opposite directions to each other, and the two divided wheel parts are controlled to rotate relative to each other around the wheel axis via the two actuating members. This creates a phase difference between the teeth of the two divided wheel parts, eliminating backlash between the teeth and the meshing wheel.

(Example) As shown in Fig. 1, when a plane P is rolled on a cylindrical surface with a diameter d, the thread surface drawn in space by a straight line with an inclination angle β in the P plane is an involute helicoid, This cylinder is called the basic cylinder.

The curve drawn by point A on the axis-perpendicular cross section M of the involute helicoid is an involute curve AA'.

If we consider these properties in reverse, if the involute helicoid surface is cut by the facet P to the basic cylinder, a generatrix A'-B will appear as the cross-sectional contour, so it is The cross-sectional contour is a straight line with a pressure angle β1.

This involute helicoid surface belongs to the truncation curved surface among developable surfaces, and has characteristics that are particularly convenient for machining, such as grinding.

A screw grinder is used to process the involute worm. In this case, the grindstone 11 formed at the angle β1 is used, and the axis of the grindstone is held parallel to the same plane as the axis 13 of the workpiece 12 as shown in FIG. 2 without inclining the axis of the workpiece 12. Grinding is performed by synchronizing the rotation of No. 13 and the feed of the grindstone shaft.

Involute worm 1 formed as described above
The mating worm wheel 14 that meshes with the worm wheel 5 uses a spur gear as shown in FIG. Since this spur gear worm wheel 14 can be ground, it is much easier to process than the normal worm wheel 2 shown in FIG. 10, and moreover, it can be manufactured with high precision.

Involute worm 1 processed as described above
5 and the worm wheel 14 are engaged and driven, as shown in FIGS. 4 and 5, the tooth surfaces of both contact 21.
．． 22 occurs on the wheel tooth surface at a position offset from the axis 23 to the left and right by 1/2 of the base cylinder diameter d, that is, the radius of the base cylinder, from the axis 23 of the involute worm, and is located on the left tooth surface. is its surface,
The right tooth flank will occur tangentially to the base cylinder in its backing.

From the above facts, it is known that even if the worm wheel is divided into two from the center in the tooth width direction, the tooth portion of the divided portion will not be in the contact position. Therefore, even if the worm wheel is divided into two parts in the tooth width direction, no problem will occur in meshing transmission.

Based on the above facts, the present invention divides the worm wheel into two parts in the tooth width direction, and these divided wheel parts 14a,
14b is used in combination to eliminate backlash.

Embodiments of the method and apparatus for removing backlash according to the present invention will be explained with reference to FIGS. 6 to 8.

15 is an involute worm, and 14 is a worm wheel that meshes with the worm wheel, which consists of divided wheel parts 14g and 14b divided into two from the center in the tooth width direction, and the divided wheel part +4b is fitted into the boss part 16 of the divided wheel part +41. , are fixed by screws 15.

The involute worm 15 is connected via a coupling 25 to a motor 26 as a drive source.

Further, the worm wheel 14 is keyed to a main shaft 18 supported by a bearing 2o and fixed with a nut 19.

The adjustment mechanism for backlash removal is configured as follows. In FIG. 8, the pin 31 fixed to one split wheel part +41 with a screw and the other split wheel part +4b
There is a pin 30 fixed with a screw to the pin 30, heads 32 and 33 are respectively fitted to both pins, and opposite left and right threads are cut at both ends into screw holes provided opposite to these heads. A turnbuckle 34 is screwed together.

After installing the involute worm 15 and the worm wheel 14 as a drive mechanism at a predetermined operating position, by adjusting the rotation of the turnbuckle 34, the distance between the pin 3G and the pin 31 is adjusted. 14! and 14b are rotated relative to each other around the axis of the worm wheel 14, and backlash as shown in FIG. 9(g) can be removed as shown in FIG. 9(b).

〔Effect of the invention〕

Although the backlash removal device for the involute worm drive mechanism of the present invention is slightly inferior to a normal worm reduction mechanism in terms of load capacity, it is easy to manufacture high-precision products because both the involute worm and the worm wheel can be ground. At the same time, backlash can be significantly reduced when the load is light. Therefore, when the removal device of the invention is used to reduce the end of the drive part of a servomechanism, the predetermined motion state is transmitted very accurately and the servo gain can be significantly increased.

Furthermore, since the worm wheel is divided into two in the tooth width direction, backlash can be easily removed by relatively rotating the divided wheel portions around the wheel axis.

As mentioned above, both the involute worm and the worm wheel can be manufactured with high precision, so even if the backlash is suppressed to an extremely low level, there will be no problem with the engagement of the two, and therefore, extremely accurate operation can be achieved. It is possible to obtain a servo mechanism that

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an involute helicoid, Fig. 2 is an explanatory diagram showing the involute worm processing method of the present invention, and Fig. 3 is an explanatory diagram showing the involute worm drive mechanism of the present invention (0 is a partial front view). Figures 4 and 5 are for explaining the contact state of the tooth surfaces when the involute worm and worm wheel of the present invention are engaged. Partial cross section, 5th
The figure is a partial top view, Figures 6 to 8 show a backlash removal device for an involute worm drive mechanism of the present invention, Figure 6 is an overall view, and Figure 7 is a partial top view of Figure 6.
■Cross-sectional view, Figure 8 is the ■--■ cross-sectional view of Figure 6, Figure 9 (0
9(b) is an explanatory diagram of the situation of backlash, FIG.
Figure 0 shows an example of a conventional worm gear.
1 to 13 are explanatory diagrams showing different examples of conventional techniques for removing backlash. 14... Worm wheel, 14g, 14b...
Split wheel part, 15... Involute worm, 3
0, 31...Divided wheel part 14! , 14b respectively fixed pins as actuating members, 34... turnbuckles as adjusting members.

Claims (2)

[Claims] (1) The worm wheel on the other side that meshes with the involute worm is constructed by combining spur gears that are divided into two in the tooth width direction, and these are rotated relative to each other around the wheel axis to provide a phase difference to eliminate backlash. Backlash removal method for involute worm drive mechanism. (2) The other worm wheel that meshes with the involute worm is constructed by combining spur gears divided into two parts in the tooth width direction, and two actuating members fixed to each of these divided wheel parts are An adjustment member that can freely adjust the spacing between the members is connected, and by adjusting the adjustment member, the divided wheel portion can be relatively rotated around the wheel axis via the operating member. Backlash removal device for involute worm drive mechanism.