Ball worm gear pair

Abstract

The invention belongs to the field of mechanical transmission. Ball worm gear pairs are broadly applied to transmission between two spacially crossed axles; movement can be decelerated or accelerated; decelerated movement, of which the crossed axis angle sigma is equal to 90 degrees, is the most common one; the ball worm gear pairs are used in various types of mechanical transmission, including heavy-duty power transmission, and are frequently applied to precise indexing transmission between machine tools and precise instruments. The invention particularly relates to a ball worm gear pair which can be a single-head enveloping ball worm gear pair with a ball circulating in the worm and a multi-head enveloping ball worm gear pair with a ball circulating in the worm. The two embodiments of the ball worm gear pair provided by the invention are simple in structure, convenient to process, and safe and reliable in work, so as to meet needs of different types and purposes; the ball worm gear pair is provided on the basis of the key technique in ball worm gear transmission--the approach and method for the circulating reflux of balls.

Description

technical field [0001] The invention belongs to the field of mechanical transmission and is widely used in the transmission between two spatially interleaved axes. The movement can be deceleration or acceleration. The most common is the deceleration movement with the axis angle Σ=90 degrees. The traces are all over various types of machinery. Among them, there are heavy-duty power transmissions, and they are also commonly used in the precision indexing transmission of machine tools and precision instruments, specifically involving a ball-worm pair. Background technique [0002] Worm gear transmission is widely used in mechanical equipment. The main advantages are stable transmission, small vibration impact, low noise, simple and compact structure, large transmission speed ratio, and the primary reduction ratio is generally 5 to 70, and the maximum can reach hundreds. [0003] The main disadvantage of worm drive is: during the transmission process, the sliding friction betwee...

AI Technical Summary

Problems solved by technology

[0003] The main disadvantages of worm drive are: during the transmission process, the sliding friction between the worm thread and the side of the worm wheel thread is very large, resulting in rapid heating, high temperature rise, high energy consumption, and low efficiency, which is also the root cause of the failure of worm and worm drive.

[0014] Second, the practical scope is strictly limited

It is not applicable to the ball-worm worm gear pair with the characteristics described in this case, because the edge of its disc-shaped end cover can only reach the maximum diameter of the ball, and cannot go deep into the bottom of the spiral groove of the worm, and cannot guide the ball to circulate and return

[0015] Documents ③ and ④ are all schemes of ball circulation in the worm, and there are also some shortcomings. For example, the inner cavity of the worm in document ③ has some accessories. The ball circulation channel is too complicated, which has an adverse effect on the transmission efficiency, and the production and processing volume Increase, also need to increase the diameter of the worm and the assembly size of one end

[0016] The first ball circulation method in document ④ comes from the ball screw pair. The ball screw and the nut are in full-circle contact, and there are 3 to 5 rows of balls loaded at the same time. The ratio is very small, which has little effect on the bearing capacity of the screw pair, and the centrifugal force on the balls on the worm is not conducive to the orbit-changing movement, which is just the opposite of the ball screw, so it is necessary to reduce the orbit-changing inclination angle and increase the changing orbit rail length, and the spiral groove on the worm wheel is very short, the reduction of the bearing capacity due to the rail change cannot be underestimated. The second type of circular ball return, that is, the intubation type, will cause a greater loss of load capacity than the first type. This is the worm A solution that is difficult for designers to accept

The third circulation method, the keyed bead returner, seems to be better in theory, but the worm should be divided into two parts, the worm sleeve and the worm. effectively fixed

Before work, the spiral groove is full of balls, and this phenomenon will appear when the worm rotates: the balls before the midpoint move forward faster, and if there is no block in front, the distance between the balls will also increase as they go forward; on the contrary, Since the moving speed of the ball at the midpoint is the slowest, after the midpoint, the moving speed should be faster as it moves backwards, but it cannot move forward due to the obstruction of the front balls, so the balls in the second half will inevitably be squeezed tightly and cause the worm- The pure rolling friction between the ball and the worm wheel cannot be realized, and there must be accompanying sliding friction, thereby increasing energy consumption and reducing transmission efficiency

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