JP3715038B2 - Backlash removal feed screw device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a feed screw device used in a mechanism or the like that converts rotational motion into linear reciprocating motion, and more particularly to a backlash removal feed screw device that attempts to remove the backlash.
[0002]
[Prior art]
Conventionally, various feed screw devices that have been provided with a pre-load by a compression spring have been proposed as a feed screw device for removing backlash. FIG. 5 shows an example of this. A main nut 52 and a sub-nut 53 that are screwed onto the screw shaft 51 are coupled to each other in the axial direction by a guide pin 54 in a non-rotating state, and are axially connected to each other by a compression spring 55. It is energized.
[0003]
[Problems to be solved by the invention]
However, in this type of feed screw device, the preload amount and the rotational torque tend to have a relationship as shown in FIG. 5B, and if the preload is applied too much, the rotational torque becomes heavy and wear increases.
In order to adjust the amount of preload, it is necessary to change the spring constant of the spring 55, and cannot be adjusted after being assembled in the apparatus. Therefore, it is necessary to remove and reassemble the nut. Moreover, it is necessary to make several kinds of things with different spring constants, and it is necessary to find an optimum value while reassembling several times.
[0004]
This invention solves the said subject, and provides the backlash removal feed screw apparatus which can adjust the preload amount for backlash removal easily, and can adjust the preload amount easily even after attaching to an apparatus. With the goal.
[0005]
[Means for Solving the Problems]
The backlash removal feed screw device according to the present invention includes a main nut and a sub-nut that are respectively screwed into a screw shaft, an elastic body that urges the main nut and the sub-nut in the axial direction, and the sub-nut as a main nut. On the other hand, there is provided an adjustable detent means for preventing the rotation by adjusting the relative rotation angle.
According to this configuration, since the main nut and the sub-nut are urged in the axial direction by the elastic body, the backlash is removed and preload is generated. In this case, by changing the rotation angle of the auxiliary nut with respect to the main nut by the adjustable detent means, the phase relationship of the thread grooves provided in these nuts changes, and the shaft of the main nut and the auxiliary nut relative to the screw shaft changes. The preload amount is adjusted because the direction position is shifted. This adjusted amount of preload is maintained by the detent action of the adjustable detent means. For this reason, even after this screw device is attached to various devices, the backlash can be removed and fine adjustment can be performed while confirming the backlash and the rotational torque.
[0006]
In this configuration, the adjustable detent means includes axial grooves provided at a plurality of locations in the circumferential direction of the outer diameter surface of the secondary nut, and an axial direction of the secondary nut provided in the main nut. It shall consist of a rotation stopper engaged with a groove | channel so that axial movement is possible. The rotation stopper is elastically detached from the axial groove and re-engaged by forced rotation of the sub-nut with respect to the main nut. Since the rotation stopper engages with the axial groove of the sub-nut so as to be axially movable, it does not hinder the axial movement for adjusting the pre-load of the sub-nut relative to the main nut. Thereby, the preload amount can be adjusted with a simple configuration.
[0007]
The rotation stopper may be a ball detent or the like having a ball that engages with the axial groove and a spring that biases the ball against the sub-nut. The ball detent is provided in a radial hole formed in a cylindrical portion on the outer periphery of the sub nut of the main nut. As described above, the rotation prevention of the auxiliary nut is facilitated by forming the rotation stopper with the ball and the spring.
[0008]
The sub-nut is provided inside the main nut. Thereby, it becomes a simple external shape, and handling etc. become easy. In this case, provided the elastic member receiving recess in the circumferential direction a plurality of locations in the sub-nut facing surface of the main nut, it may be the resilient member provided on the respective elastic member receiving recess. As a result, the elastic body is not exposed to the outside, and the appearance becomes simpler.
[0009]
In these configurations, the screw shaft may be made of metal, and the main nut and the sub-nut may be made of resin. By using resin as described above, good slip due to self-lubricating properties can be obtained, and the molding of the main nut and the sub-nut can be simplified.
Further, when configuring the adjustable detent means as said in said axial groove and detent member, a leaf spring kicked set integrally molding the detent member in the sub-nut, the leaf spring It is good also as what consists of an engaging part which is provided in the front-end | tip of this and engages with the said axial groove | channel. Thereby, an adjustable rotation stop means becomes a simple structure.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIG. The backlash removal feed screw device includes a main nut 2 and a sub-nut 3 that are respectively screwed into the screw shaft 1, an elastic body 4 that urges the main nut 2 and the sub-nut 3 in the axial direction, and the sub-nut. 3 is provided with adjustable detent means 5 for derotating 3 with respect to the main nut 4 so that the relative rotation angle can be adjusted. The screw shaft 1 is made of metal, and the main nut 2 and the sub-nut 3 are made of resin.
[0011]
The main nut 2 is formed in a cylindrical shape having a flange portion 2a at one end, the inner diameter surface is formed in a stepped cylindrical surface shape, and the portion on the flange portion 2a side of the inner diameter surface is formed in a small-diameter female screw portion 2b. Has been. A portion of the main nut 2 on the side opposite to the flange portion 2a is a cylindrical portion 2c serving as a sub-nut accommodating recess having a large inner diameter surface. On the step surface of the main nut 2 that faces the sub-nut, round-hole-shaped elastic body accommodating recesses 6 are provided at a plurality of circumferential locations (for example, three locations), and a compression coil spring is provided in each recess 6. the elastic body 4 made that have been accommodated. The elastic body 4 may be rubber-like. Is different from the present invention, the elastic body accommodation recess 6 forms a circumferential groove instead of a local round holes as described above, the reference proposed example is shown in Figure 2 (A) ~ (C) as shown each example, the disc spring and the internal thread portion 2b concentrically, but it may also be those provided overlapping the ring-shaped spring member V-shaped or U-shaped cross-section in the axial direction.
[0012]
The adjustable detent means 5 has a ratchet mechanism-like shape, and has axial grooves 7 provided at equal pitches at a plurality of positions in the circumferential direction of the outer diameter surface of the sub-nut 3 that is formed into a cylindrical surface. It consists of the rotation stopper 8 which engages. The axial groove 7 has a semicircular cross-sectional shape as shown in FIG. 3B. However, as shown in FIGS. 3A and 3B, the axial groove 7 has a V-shaped cross section, a rectangular cross section, a trapezoidal shape, or the like. It may have a cross section. The rotation stopper 8 is provided on the main nut 2 and engages with the axial groove 7 of the sub-nut 3 so as to be axially movable, and is elastically moved from the axial groove 7 by the forced rotation of the sub-nut 3 with respect to the main nut 2. To disengage or re-engage. In this example, the detent 8 includes a ball detent (also referred to as “ball point”) having a ball 9 that engages with the axial groove 7 and a spring 10 that biases the ball 9 against the sub-nut 3. , And is accommodated in a screw cylinder-shaped rotation stopper main body 11 with a bottom. The rotation stopper main body 11 is screwed into a radial hole formed by a screw hole formed in the cylindrical portion 2 c on the outer periphery of the sub nut of the main nut 2. In this example, the rotation stoppers 8 are provided equally at a plurality of locations (for example, 3 locations) in the circumferential direction as shown in FIG.
[0013]
According to the screw device having this configuration, the main nut 2 and the sub-nut 3 are urged in the axial direction by the elastic body 4, so that the backlash is removed and preload is generated. In this case, by rotating the sub-nut 3 with respect to the main nut 2, the phase relationship between the thread grooves of the main nut 2 and the sub-nut 3 changes, and the shafts of the main nut 2 and the sub-nut 3 with respect to the screw shaft 1 are changed. The direction position will shift. Therefore, the preload amount is adjusted. When the sub-nut 3 is rotated with respect to the main nut 2, the ball 9 is retracted against the urging force of the spring 10 and detached from the axial groove 7. Therefore, the subnut 3 can be rotated. By this rotation, the ball 9 repeats the operation of being sequentially fitted into and removed from the axial grooves 7 of the sub-nut 3. The adjustment is finished in a state where the sub-nut 3 is turned to a desired rotation angle and the ball 9 is engaged with the axial groove 7. The rotation stop of the sub-nut 3 by the ball 9 is maintained in the rotation stop state and the adjusted preload amount is maintained in the normal feed operation by the relative rotation of the screw shaft 1 and the nuts 2 and 3.
[0014]
For this reason, even after this screw device is attached to various devices, the backlash can be removed and fine adjustment can be performed while checking the backlash and the rotational torque. Moreover, since the subnut 3 is stored in the main nut 2 in this screw device, the external appearance becomes a simple shape. When the adjustable detent means 5 urges the ball 9 with the spring 10 as described above, the ball 9 is easily detached from the axial groove 7 and the auxiliary nut 3 is easily rotated. When the main nut 2 and the sub-nut 3 are made of resin, good slippage between the screw shaft 1 and the self-lubricating property of the resin can be obtained.
[0015]
In the above embodiment, the anti-rotation device 8 of the adjustable anti-rotation means 5 is constituted by the ball 9 and the spring 10, but as shown in FIG. 4 (A), the anti-rotation device 8 is an integral rubber or resin. It is good also as what consists of a made pin-shaped elastic body. Further, as shown in FIG. 4 (B), the rotation stopper 8 includes a leaf spring 8a provided integrally with the sub-nut 3 and a distal end of the leaf spring 8a. It is good also as what consists of the hemispherical engaging part 8b to engage.
Furthermore, in all of the above embodiments, the axial grooves 7 are provided on the outer diameter surface of the sub-nut 3, but for example, axial grooves are provided at a plurality of locations in the circumferential direction of the inner diameter surface of the main nut 2 in the example of FIG. The sub-nut 3 may be provided with a rotation stopper that is elastically engageable and disengageable to constitute an adjustable detent means.
[0016]
【Example】
In the feed screw device having the configuration shown in FIG. 1, when the main nut 2 and the sub-nut 3 are made of resin, it is possible to use a material that can be injection-molded, has self-lubricating properties, and has excellent mechanical strength. preferable. Examples of such resins include polyimide resins, polyarylene sulfide resins, molten fluorine resins, epoxy resins, polyethylene resins, polyacetal resins, polyamide resins, and tetrafluoroethylene / ethylene copolymer resins (ETFE). ) Etc. As a material for the nuts 2 and 3, when selecting a material having mechanical strength and dimensional stability and good wear resistance, for example, a polyimide resin, a polyamideimide resin, a polyetherimide resin, Polyphenylene sulfide resin, epoxy resin, polyether ketone resin, polyether sulfone resin and the like can be used. In addition, when the nut 2, 3 resin is a thermoplastic resin, it has moderate rigidity, excellent mechanical strength, injection moldability is possible, a complex shape, excellent moldability such as precision dimension moldability, A polyphenylene sulfide resin having excellent performance on average, such as efficient mass productivity by injection molding, and price, is preferable.
[0017]
Various kinds of fillers, oils, and the like may be mixed in the respective resins. That is, in order to improve the self-lubricating property of the synthetic resin, it may be filled with a solid lubricant such as fluororesin, molybdenum disulfide, graphite, mica, lead, lead oxide, boron nitride, tungsten disulfide, Further, for the same reason, lubricating oil, for example, various synthetic oils such as fluorine oil and silicone oil, wax, grease and the like may be included. Moreover, in order to adjust the degree of elastic deformation and the sound absorption effect of the synthetic resin, as a modifier of mechanical properties to the above synthetic resin, for example, glass fiber, carbon fiber, potassium titanate fiber, talc, white carbon, metal, Metal oxide, ceramic powder, organic fiber, etc. may be filled. If at least one of these fillers is added, for example, 5 to 30% by weight, preferably 10 to 25% by weight, of a lubricant and a fiber, the slidability and strength can be improved.
The material of the synthetic resin can be appropriately selected depending on the use environment conditions. For example, a fluorine resin can be used in a chemical solution, and a polyimide resin can be used in a place where radiation is a problem.
The screw shaft 1 is formed of a metal material such as steel or an aluminum alloy, but the screw surface may be coated with a resin layer having a small friction coefficient, such as polytetrafluoroethylene. In that case, better sliding performance can be obtained by the self-lubricating property of the resin layer. The surface roughness / shape of the sliding portion is about 25 μm or less, preferably JIS definition such as maximum roughness (Rmax), arithmetic average roughness (Ra), ten-point average roughness (Rz), etc. , About 8 μm or less, and more preferably about 3.2 μm or less. If the surface roughness / shape is too large, it is considered to cause wear. The lower limit is not particularly limited, but may be 0.1 μm or more and 1 μm or more in consideration of workability efficiency. Smaller surface roughness / shape may be better, but it will take a lot of time for the processing work, and if there is no significant difference depending on the specifications / conditions, the surface roughness / shape processing work, In order to omit the management work, the surface roughness / shape may be about 3 to 10 μm.
[0018]
【The invention's effect】
The backlash removal feed screw device according to the present invention includes a main nut and a sub-nut that are respectively screwed into a screw shaft, an elastic body that urges the main nut and the sub-nut in the axial direction, and the sub-nut as a main nut. Because it is equipped with adjustable detent means for preventing rotation by adjusting the relative rotation angle, it is easy to adjust the amount of preload for removing backlash, and it is easy to preload even after assembly Ru can adjust the amount.
Since the secondary nut is provided inside the main nut, it has a simple external shape and is easy to handle. In addition, since the elastic body accommodating recesses are provided at a plurality of locations in the circumferential direction on the sub nut facing surface of the main nut, and the elastic bodies are provided in each of these elastic body accommodating recesses, the elastic body is not exposed to the outside, and a simpler appearance It becomes.
[Brief description of the drawings]
FIG. 1A is a sectional view of a feed screw device according to an embodiment of the present invention, and FIG.
FIGS. 2A to 2C are cross-sectional views of a peripheral portion of an elastic body showing modifications of the elastic body of the feed screw device as reference proposal examples .
FIGS. 3A and 3B are cross-sectional views showing modifications of the axial groove in the sub-nut.
4A and 4B are cross-sectional views showing modifications of the adjustable detent means, respectively.
5A is a cross-sectional view of a conventional example, and FIG. 5B is a graph showing the relationship between the amount of preload and rotational torque.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Screw shaft 6 ... Elastic body accommodation recessed part 2 ... Main nut 7 ... Axial groove 3 ... Sub nut 8 ... Anti-rotation tool 4 ... Elastic body 9 ... Ball 5 ... Adjustable anti-rotation means 10 ... Spring

Claims (4)

A main nut and a sub-nut that are respectively screwed to the screw shaft, an elastic body that urges the main nut and the sub-nut in the axial direction, and a relative rotation angle of the sub-nut with respect to the main nut can be adjusted. e Bei the adjustable detent means for the detent, the adjustable detent means, said axial groove provided in the circumferential direction a plurality of locations of a cylindrical surface shape and has an outer diameter surface of the secondary nut, the main A rotation stopper provided on the nut and engaged with an axial groove of the auxiliary nut so as to be axially movable, and elastically released from the axial groove and re-engaged by forced rotation of the auxiliary nut with respect to the main nut; The auxiliary nut is provided inside the main nut, and elastic body receiving recesses are provided at a plurality of locations in the circumferential direction on the surface of the main nut facing the sub nut, and the elastic body is provided in each elastic body receiving recess. Crushing removal feed screw device. The detent includes a ball that engages with the axial groove and a spring that biases the ball against the sub-nut, and is provided in a radial hole formed in a cylindrical portion on the outer periphery of the sub-nut of the main nut. The backlash removal feed screw device according to claim 1 . The backlash removal feed screw device according to claim 1 or 2 , wherein the screw shaft is made of metal, and the main nut and the sub-nut are made of resin. The screw shaft is made of metal, the main nut and secondary nut is made of resin, a plate spring provided integrally molded before Symbol rotation stop said secondary nut, provided at the tip of the leaf spring The backlash removal feed screw device according to claim 1, further comprising an engaging portion that engages with the axial groove.

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