Wheel disc backflow type precise ball worm and gear

Abstract

A wheel disc backflow type precision ball worm gear belongs to the field of machinery. The device structurally comprises a worm gear, a worm and a supporting part, wherein the worm gear structurally comprises a worm gear disc, a steel ball return channel and a worm gear shaft, and the worm structurally comprises a worm shaft and a spiral body; a groove with a semicircular section and a steel ball channel are processed on the peripheral cylindrical surface of the worm wheel disc, so that the steel balls can roll and circulate along a closed path formed by the steel ball channel, the ball guide pipe and the return channel; a spiral body of the worm is a columnar object with a spiral groove in the side face, and the spiral groove surrounds the columnar surface of the worm pair. The cover body restraining part of the supporting part covers all exposed groove parts of the worm gear, and the steel balls are restrained from being separated from the steel ball channels in the grooves; when power torque enables the worm to rotate, the steel balls generate tangential force advancing and retreating in the thread direction under the thrust of the threads, all the steel balls of the closed steel ball linear array generate follow-up queuing circulating displacement, and the power rotating disc can be widely used as a power rotating disc of a machine tool.

Description

Technical Field

[0001] The present invention belongs to the field of mechanical technology. Specifically, it is a worm and worm gear mechanism in which rolling steel balls embedded in a wheel disc are used as teeth-like contacts to improve the running accuracy and suppress high friction. Background Art

[0002] The worm and worm gear structure is often used to transmit motion and power between two intersecting shafts. The worm and the worm gear are equivalent to a gear and a rack in their intermediate plane, and the worm is also similar in shape to a screw.

[0003] Basic parameters: module m, pressure angle, worm diameter coefficient q, lead angle, number of worm heads, number of worm gear teeth, addendum coefficient (taking 1) and backlash coefficient (taking 0.2). Among them, the module m and the pressure angle refer to the module and pressure angle of the worm's axial plane, that is, the module and pressure angle of the worm gear's end face, and both are standard values; the worm diameter coefficient q is the ratio of the worm's pitch diameter to its module m.

[0004] Operating characteristics: 1. A large transmission ratio can be obtained, which is more compact than the intersecting-axis helical gear mechanism. 2. The meshing tooth surfaces of the two wheels are line contacts, and their load-carrying capacity is much higher than that of the intersecting-axis helical gear mechanism. 3. The worm drive is equivalent to a screw drive and is a multi-tooth meshing drive, so the transmission is stable and the noise is very small. 4. It has self-locking property. When the lead angle of the worm is less than the equivalent friction angle between the meshing teeth, the mechanism has self-locking property and can achieve reverse self-locking, that is, only the worm can drive the worm gear, and the worm gear cannot drive the worm. For example, the self-locking worm mechanism used in hoisting machinery, its reverse self-locking property can play a safety protection role. 5. The transmission efficiency is relatively low and the wear is relatively serious. When the worm and worm gear are meshing and transmitting power, the relative sliding speed between the meshing teeth is large, so the friction loss is large and the efficiency is low. On the other hand, the large relative sliding speed causes serious tooth surface wear and heat generation. In order to dissipate heat and reduce wear, materials with relatively expensive anti-friction and anti-wear properties and good lubrication devices are often used, so the cost is relatively high. 6. The axial force of the worm is relatively large.

[0005] General situation of advantages and disadvantages

[0006] Compared with other forms of gear transmission, the worm and worm gear transmission has the following advantages and disadvantages.

[0007] Advantages

[0008] Single-stage speed ratio is large

[0009] The single-stage speed ratio of cylindrical gear transmission and bevel gear transmission is generally up to about 1 / 10 at most, while the worm and worm gear transmission with a speed ratio of 1 / 70 - 1 / 100 is easy to manufacture. Therefore, the worm and worm gear transmission reducer can achieve a large speed ratio with a smaller overall dimension. The comparison between worm and worm gear reducers with speed ratios of 1 / 5, 1 / 25, 1 / 70, and 1 / 150 and helical gear reducers, their transmitted power is 30 horsepower and the input shaft speed is 1200 rpm.

[0010] Low noise and small vibration during operation: When cylindrical gears and bevel gears mesh, it is mainly rolling contact, while for worm gears, it is mainly sliding contact. Therefore, there are fewer factors causing noise and vibration. For this reason, worm and worm gear reducers are preferred for driving escalators, elevators, moving walkways, and machines for preventing public nuisances in recent years.

[0011] With a worm and worm gear reducer, the shafts can be arranged vertically without intersecting: The arrangement of the worm shaft and the worm gear shaft can sometimes save the installation area of the prime mover and the driven machine while being convenient and reasonable.

[0012] Reverse rotation can be prevented: When the lead angle of the worm is less than the friction angle, theoretically the worm cannot be driven by the worm gear, that is to say, a self-locking worm drive can be designed. However, in practice, the tooth surface friction coefficient changes from the static friction coefficient to the dynamic friction coefficient due to reasons such as vibration, so it may sometimes rotate slowly, and it is difficult to achieve complete self-locking.

[0013] Disadvantages: The existing worm and worm gear mechanisms all operate in a tooth contact mode with high friction. In addition to low transmission efficiency and tooth backlash, the contact area of the contact line between teeth is also very limited.

[0014] Low efficiency: Compared with other forms of gear transmission, the worm and worm gear transmission has large tooth surface friction losses and low efficiency when transmitting power. Currently, due to the improvement of manufacturing methods, an efficiency close to the theoretical value can be achieved. Some worm and worm gear transmissions can reach an efficiency of 98% when the speed ratio is 1 / 5 and the worm speed is 180 rpm. However, with the same center distance, when the speed ratio is 1 / 70 and the worm speed is 200 rpm, the efficiency is about 60%.

[0015] Easy to produce tooth surface adhesion: For involute tooth form cylindrical gears, when the tooth surface bears a load, due to the deformation of each part, the tooth contact state changes for the better, while for the worm and worm gear transmission, the tooth contact state changes for the worse, that is, it deforms in the direction of tooth surface oil film rupture, and tooth surface adhesion is easy to occur. Therefore, the tooth contact state and bearing clearance during assembly should be estimated considering the deformation amount. It is also necessary to be as careful as possible during the running-in operation.

[0016] Lifespan and cost issues: The worm and worm gear drive uses copper alloy materials. Since there is generally no dedicated gear cutting machine, the gear cutting processing efficiency is low, and it is very time-consuming to manually trim the tooth surface. Summary of the Invention

[0017] Object of the present invention:

[0018] To overcome the deficiencies of the prior art, improve the high-friction contact mode between the worm and the worm gear, and improve adverse factors such as low transmission efficiency and limited service life.

[0019] Features of the present invention: Compact structure, high transmission efficiency and transmission accuracy, and long service life.

[0020] Key technology of the present invention: Create the conditions for rolling friction, and cleverly use a string of steel balls in the closed-loop return on the wheel disc to achieve rolling friction of steel balls instead of sliding friction.

[0021] Specific content of the invention:

[0022] The wheel disc return type precision ball worm and worm gear is composed of three major components: including a worm gear, a worm and a support component; among them, the structure of the worm gear includes a worm gear disc, a steel ball return channel and a worm gear shaft, and the structure of the worm includes a worm shaft and a spiral body; the support component is provided with a worm shaft hole and a worm gear shaft hole for installing and restricting the worm shaft and the worm gear shaft of the worm and the worm gear to rotate freely under the support of bearings; since the support component connects the worm shaft hole and the worm gear shaft hole into a whole, a driving relationship is formed between the worm gear and the worm.

[0023] The structure of each component is as follows: The worm gear component includes a worm gear disc part and a worm gear shaft (power output shaft) part. On the peripheral cylindrical surface of the worm gear disc, a groove with a semicircular cross-section is processed. The groove surrounds the entire circumference of the worm gear disc to form a closed ring groove (semicircular cross-section) structure. The circumferential lines at both ends of the worm gear are equivalent to the two sides of the closed ring groove; on the bottom surface of the above-mentioned ring groove, a group of equally spaced and uniformly arranged non-intersecting steel ball channels are processed. The steel ball channels have a semicircular cross-section, and the channels obliquely span between the "two sides" of the groove; at both ends of the steel ball channels, ball return holes are opened, and the ball ducts connect the ball return holes and the return channels, so that the steel balls can roll and circulate along the closed path composed of the steel ball channels, the ball ducts and the return channels; when the steel balls fill the ratio and path, the steel balls are arranged to form a closed steel ball line array.

[0024] The worm (pair)'s spiral body is a cylindrical object with a spiral groove on its side. The spiral groove surrounds the cylindrical surface of the worm pair. The worm shaft and worm wheel shaft are constrained by the worm shaft hole and worm wheel shaft hole of the support component, and can rotate freely under the support of the bearing. The restraining cover of the support component covers all exposed grooves of the worm wheel, restraining the steel balls from falling out of the steel ball grooves on the grooves.

[0025] To increase thrust, the spiral and grooves that accommodate the steel balls in the worm and worm wheel can be single-start or multi-start, and the number of corresponding return channels is also increased to multiple starts. The reason for considering multiple starts is that, under the mathematical geometric relationship of the relative uniform rotation of the spiral body and the closed annular groove of the worm wheel disc, only the steel balls in the local grooves and spiral grooves can meet the close contact relationship during operation without excessive gaps. Therefore, multiple worms are required in series to meet the requirements of high load torque.

[0026] Working principle of high rigidity precision ball worm gear system:

[0027] Because the supporting component connects the worm shaft hole and the worm wheel shaft hole into a whole, a driving relationship is formed between the worm wheel and the worm; the mechanical contact between the worm wheel and the worm is achieved through the steel ball clamped between the steel ball groove of the worm wheel and the spiral groove of the worm: It should be emphasized that the ball guide tube can be directly processed on the worm wheel; the worm component can be used alone, and can also be used in series to increase torque with multiple worm components.

[0028] When the spiral groove of the worm (pair) is matched with the steel ball groove of the worm wheel, the steel balls are just filled and sandwiched between the spiral groove of the worm body and the steel ball groove of the worm wheel. Like a conventional ball screw, when the worm (pair) is rotated, the torque is transmitted through the steel balls as a medium, thereby driving the worm wheel to rotate; the steel balls generate a tangential force that advances and retreats along the direction of the thread under the thrust of the thread, and the pushing effect between the various steel balls transmits force and torque, thereby driving the worm wheel to rotate, and at the same time, the steel balls also generate spiral motion along the spiral groove, and all the steel balls in the closed steel ball line produce follow-up queued cyclic displacement.

[0029] Furthermore, to increase the transmission torque of the speed reduction mechanism, multiple worm components can be used in series; that is, the worms in the high-rigidity precision ball worm and worm gear are connected in series. The worm shaft can extend to connect one end shaft of the shaft transmission component, and the other shaft end is then connected to the worm shaft of the next worm (forming a hand-in-hand form). The shaft transmission component consists of an end shaft, an off-axis orthogonal shaft body, and a hinge rod. The end shaft is a connecting piece rigidly connected to the power shaft and having a connection member perpendicular to the rotation shaft or shaft hole of the power shaft. The off-axis orthogonal shaft body is an intermediate body of two sets of rotation shafts (or off-axis rotation shafts) with orthogonal axes or an off-axis slideway of the shaft hole. The hinge rod is a component connecting two orthogonal shaft bodies through a hinge shaft or an off-axis hinge shaft (or a component of orthogonal shaft bodies with non-intersecting axes). Working principle: Since both of the two orthogonal shafts have the pointing function of a universal joint, any movement of the two shafts can be coordinated and completed through the intermediate body. The inserted shaft transmission component is a common one in the industry, including common ones such as a cross shaft, a constant velocity joint, a connecting rod shaft transmission component, etc.

[0030] The inserted shaft transmission component includes common ones such as a cross shaft, a constant velocity joint, a connecting rod shaft transmission component, or is composed of an end shaft, an off-axis cross shaft body, and a sliding piece. The end shaft is a connecting piece rigidly connected to the power shaft and having a connection member perpendicular to the rotation shaft or shaft hole of the power shaft. The off-axis cross shaft body is an intermediate body of two sets of rotation shafts with orthogonal axes or an off-axis slideway of the shaft hole. The two ends of the sliding piece are components connecting the cross shaft body through a hinge shaft or an off-axis hinge shaft (or components of cross shaft bodies with non-intersecting axes).

[0031] Furthermore, the ball conduit is a selective component and does not have to be adopted. There is a return channel directly machined inside the worm, passing through the two end faces of the worm, and the balls can be directly connected to the end of the spiral groove.

[0032] Furthermore, the structure of the closed path of the steel balls on the worm gear can be directly machined on the worm gear, or a pre-machined steel ball return channel component can be used as an independently machined component and installed in a groove reserved in advance on the edge of the worm gear; this can facilitate machining, reduce the machining difficulty, and improve the machining accuracy.

[0033] The technical progress of the present invention: It completely overcomes the working principle defects of the gear system and the high-friction worm and worm gear system; it provides a rotational power transmission module comparable to the ball screw for linear displacement, and at the same time has the advantages of high precision, high rigidity (transmission torque), and high service life. [Description of the Drawings]

[0034] The following further describes the present invention with reference to the preferred embodiments of the present invention in conjunction with the drawings:

[0035] Figure 1 Front, elevation, and oblique views of the high-rigidity precision ball worm and worm gear.

[0036] Figure 2 Explosion schematic diagram of a high-rigidity precision ball worm and worm wheel.

[0037] Figure 3 Schematic diagram of the ball raceway of the worm wheel

[0038] Figure 4 Schematic diagram of the structure of the shaft transmission assembly

[0039] Figure 5 Schematic diagram of the worm wheel with a split ball raceway component

[0040] Explanation of the reference numerals in the figure:

[0041] 1 Worm wheel

[0042] 1-1 Ball raceway

[0043] 1-2 Worm wheel shaft (power output shaft)

[0044] 1-3 Worm wheel disc

[0045] 1-4 Bottom of the groove

[0046] 1-5 Ball guide tube

[0047] 1-6 Ball return hole

[0048] 1-7 Return channel

[0049] 1-8 Ball line array

[0050] 2 Worm

[0051] 2-1 Spiral groove

[0052] 2-2 Worm shaft (power input shaft)

[0053] 2-3 Spiral body

[0054] 3 Support component

[0055] 3-1 Constraint housing

[0056] 3-2 Connection structure

[0057] 3-3 Worm wheel shaft hole

[0058] 3-4 Worm shaft hole

[0059] 4 Shaft transmission assembly

[0060] 4-1 End shaft

[0061] 4-2 Hinge rod

[0062] 4-3 (With an off-axis) Orthogonal shaft body 4-4 Ring notch protrusion

[0063] 4-5 Ring notch groove

[0064] Axis 2 between 4 - 6

[0065] Axis 3 between 4 - 7

[0066] Axis 1 between 4 - 8

[0067] 5 steel balls

[0068] Linear array of 6 steel balls

[0069] 7 motors

[0070] Worm wheel of the 8 - rear - inlaid steel ball circulating component

[0071] Steel ball return channel component of 8 - 1

[0072] 8 - 2 groove

[0073] 9 connecting screw heads

[0074] 10 fixing screws [Specific implementation manner]

[0075] As Figure 1 、 Figure 2 、 Figure 3 shown:

[0076] Figure 1 The front view of the disk - return - type precision ball worm and worm wheel is at the lower left, the rear view is on the right; the top view is at the upper left. Figure 2 is an exploded view placed in the oblique - square - azimuth. Figure 3 The perspective view of the worm wheel is at the upper left of , and the partial enlarged view of a free steel ball in a ball channel is on the right.

[0077] The disk - return - type precision ball worm and worm wheel consists of three major components: worm wheel component 1, worm component 2, and support component 3. When necessary, an axial transmission component 4 is added to increase its transmission torque;

[0078] The structural details of each component are as follows: the worm wheel component 1 is composed of a worm wheel disc 1-3 and a worm wheel shaft (power output shaft) 1-2 rigidly connected thereto. A groove with a semicircular cross-section is machined on the peripheral cylindrical surface of the worm wheel disc 1-3. The bottom of the groove 1-4 surrounds the circumference of the entire worm wheel disc 1-2 to form a closed ring groove. The circumferential lines of the two circumferential surfaces at both ends of the worm wheel are equivalent to the two sides of the closed ring groove; a steel ball groove 1-1 is machined in the groove around the worm wheel disc 1-3. The steel ball groove is A family of semicircular cross-section channels are arranged at equal intervals and do not intersect each other, obliquely spanning the groove. Ball return holes 1-6 are provided at both ends of the steel ball channel 1-1, and a ball guide 1-5 connects the ball return holes 1-6 with the return channel 1-7, so that the steel balls can roll and circulate along the closed path formed by the steel ball channel 1-1, the ball guide 1-5, and the return channel 1-7. When the steel balls fill the path, the steel balls are arranged to form a closed steel ball line 1-8.

[0079] The worm 2 is an object having a volute 2-3 with a spiral groove 2-1, and the spiral groove 2-1 surrounds the "saddle-shaped" circumferential surface of the volute 2-3; the worm shaft (power input shaft) 2-1 and the worm wheel shaft (power output shaft) 1-2 are both constrained and supported by the worm shaft hole 3-4 and the worm wheel shaft hole 3-3 of the support component 3 to rotate freely; the constraint cover 3-1 of the support component 3 covers all exposed groove parts of the worm wheel 1, constraining the steel ball 5 from falling out of the groove; specifically, it is connected by screws, as shown in the fixing screw (10) and the connecting screw head (9).

[0080] The working principle of the wheel-type recirculation precision ball worm gear: First, the connecting structure 3-2 of the support component 3 connects the worm shaft hole 3-4 and the worm wheel shaft hole 3-3 into a single unit, forming a driving relationship between the worm gear and the worm gear. When the power torque causes the worm gear 2 to rotate, it pushes the steel balls 5 to roll and circulate along the closed path formed by the steel ball channel 1-1, the ball guide tube 1-5, and the return channel 1-7. The pushing action between the individual steel balls further drives the worm wheel to rotate, and all the steel balls in the closed steel ball array produce a follow-up displacement. The drive motor 7 drives the worm shaft to rotate, which can then drive the next worm gear through the shaft transmission assembly 4. Multiple worm gears can be driven in series in a hand-in-hand manner, increasing the worm gear's capacity to transmit torque.

[0081] like Figure 4 As shown:

[0082] They are respectively the front view, the perspective view, and the exploded view of the shaft transmission component. The shaft transmission component 4 is composed of an end shaft 4-1, an off-axis orthogonal shaft body 4-3 with an off-axis, and a hinge rod 4-2; the end shaft 4-1 is a connecting piece that is rigidly connected to the power shaft and has a rotating shaft or shaft hole perpendicular to the power shaft. The off-axis orthogonal shaft body 4-3 is an intermediate body of two sets of rotating shafts (or off-axis rotating shafts) with orthogonal axes or an off-axis slideway of the shaft hole. The hinge rod 4-2 is a component that connects two orthogonal shaft bodies through a hinge shaft or an off-axis hinge shaft (or a component of orthogonal shaft bodies with non-intersecting axes); Working principle: Since both of the two orthogonal shafts have the pointing function of a universal joint, any of the two shafts can be coordinated and completed through the intermediate body. The ring notch protrusion 4-2 of the hinge rod 4-2 and the ring notch groove 4-5 on the orthogonal shaft body 4-3 are hinged off-axis, which is equivalent to rotating around the axis 24-6 and forming a cross shaft assembly with the axis 34-7; The axes 14-8 are respectively two shafts that need to transmit torque connected by the end shaft 4-1.

[0083] Such as Figure 5 shown:

[0084] The worm wheel with a split steel ball raceway component adopts: a worm wheel 8 with a post-inserted steel ball circulation component. The steel ball return channel component 8-1 is an independently processed component, which is installed into the groove 8-2 reserved in advance on the worm wheel 8 after manufacturing.

[0085] This can facilitate processing, reduce the processing difficulty, and improve the processing accuracy.

Claims

1. The wheel-disc reflow precision ball worm gear consists of three major components: a worm wheel, a worm, and a support component. The worm wheel comprises a worm wheel disc, a steel ball return channel, and a worm wheel shaft, while the worm comprises a worm shaft and a spiral body. The support component is provided with a worm shaft hole and a worm wheel shaft hole, which are used to mount and constrain the worm and worm wheel. The worm shaft and worm wheel shaft can rotate freely under the support of bearings. Because the support component connects the worm shaft hole and the worm wheel shaft hole into a whole, a driving relationship is formed between the worm wheel and the worm. Features: A groove with a semicircular cross-section is machined on the peripheral cylindrical surface of the worm wheel disc. The groove surrounds the entire circumference of the worm wheel disc to form a closed ring groove structure. The circumferential lines at both ends of the worm wheel correspond to the two sides of the closed ring groove. A group of equally spaced and evenly arranged non-intersecting steel ball grooves are machined on the groove bottom surface of the above-mentioned ring groove. The steel ball grooves have a semicircular cross-section and are obliquely across the groove. Ball return holes are opened at both ends of the steel ball grooves, and ball guide tubes connect the ball return holes and the return channel, so that the steel balls can roll and circulate along the closed path formed by the steel ball grooves, ball guide tubes and return channel. When the closed path is filled with steel balls, the steel balls are arranged to form a closed steel ball line. The spiral body of the worm is a cylindrical object with a spiral groove on the side, and the spiral groove surrounds the cylindrical surface of the worm pair; the worm shaft and the worm wheel shaft are constrained by the worm shaft hole and the worm wheel shaft hole of the supporting component, and can rotate freely under the support of the bearing; the constraint cover part of the supporting component covers all the exposed groove parts of the worm wheel, constraining the steel balls from falling out of the steel ball grooves on the grooves; the worm component is used alone or in series with multiple worm components to increase torque.

2. The roulette reflux type precision ball worm and worm wheel according to claim 1, characterized in that: The side of the worm's spiral body is provided with a spiral groove; the ball guide tube is used as a return channel, or a curved channel is directly machined inside the worm, passing through the two end faces of the worm, and the ball at the end of the spiral groove is directly connected as the return channel.

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