JP2012218044A - Method for manufacturing gear structure, and intermediate structure of the gear structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly maintain formation accuracy of a gear formed on a cylindrical member even when a portion of the outer shape of the cylindrical member is deformed upon fixing the gear of a gear structure by plastic flow.SOLUTION: In the method for manufacturing the gear structure 22, the gear structure is formed by having a first gear (one gear) 26 and a second gear (the other gear) 28 formed adjacent to each other in the axial direction on the outer periphery of a hollow shaft (cylindrical member) 24. The method includes: a first step for forming a basic tooth (groove) 26 for incorporating the first gear 26 on the outer periphery of the hollow shaft 24; a second step for forming the second gear 28 on the outer periphery of the hollow shaft 24, so that tooth bottom circle diameters 28d1, 28d2 are different from each other at both axial ends of the second gear 28; and a third step for forming the first gear 26 on the outer periphery of the basic tooth 26A by pressing a gear body 26 of the first gear 26 in the axial direction and fixing the gear body 26B by plastic flow on the outer periphery of the basic tooth 26A.

Description

  The present invention relates to a manufacturing method of a gear structure and an intermediate structure of the gear structure.

  In a power transmission device or the like, a gear structure is widely used to adjust a reduction ratio, for example. In this type of gear structure, normally two gears are formed adjacent to each other in the axial direction on the outer periphery of a shaft member. Then, the gear on one side is engaged with the gear on the front stage side of the gear structure, and the gear on the other side is engaged with the gear on the rear stage side of the gear structure. By changing the number of teeth of each gear, the reduction ratio of the entire power transmission device can be adjusted via the gear structure.

  As one of the methods for fixing the gear to the shaft member of the gear structure, for example, a reduction gear for driving a joint of an industrial robot or the like, in applications that do not like backlash, the gear is connected by using plastic flow (plastic connection). There has been proposed a method of fixing the shaft to the shaft member. This is because a groove is formed along the axial direction on the outer periphery of the shaft member, and the gear body is pushed into the outer periphery of the shaft member while applying a load in the axial direction, whereby the inner peripheral surface of the gear body is plastically flowed into the groove. It is something to be made.

  However, in this method, in the case of a gear structure in which two gears are formed adjacent to the shaft member in the axial direction, a step of forming a groove for plastic coupling to the shaft member and the adjacent groove Thus, it is necessary to carry out the step of forming the gear separately. Therefore, Patent Document 1 discloses a technique that can realize more efficient production by processing a groove for plastic bonding and a gear to be formed adjacent to the groove in a straight line (simultaneously). is doing.

JP 2010-167446 A (Claim 1, paragraph [0005])

  However, since the production method disclosed in Patent Document 1 inevitably performs plastic coupling after the adjacently formed gears are formed, the shaft member is a hollow cylindrical member. In this case, the cylindrical member may be deformed during the plastic coupling, and in particular, the formation accuracy of the gear (provided adjacent to the gear that performs the plastic coupling) may not be accurately maintained. There was a problem.

  This problem tends to become more prominent as the thickness of the cylindrical member is thinner than the outer diameter. In other words, this problem can be avoided to some extent by increasing the wall thickness of the tubular member. However, the increase in the thickness of the cylindrical member not only increases the weight and cost of the gear structure (and thus the power transmission device incorporating the gear structure), but also increases the space of the hollow portion to be secured. It means that it will become smaller, and there are great disadvantages.

  The present invention has been made to solve such a conventional problem, and accurately manufactures a gear structure in which a plurality of gears are formed adjacent to each other in the axial direction on the outer periphery of a cylindrical member. It is an object of the present invention to provide a gear structure manufacturing method that can be used, and an intermediate structure of a gear structure suitable for carrying out the manufacturing method.

  The present invention relates to a method for manufacturing a gear structure in which at least two gears are formed adjacent to each other in the axial direction on the outer periphery of a cylindrical member, and the outer periphery of the cylindrical member includes the two gears. A first step of forming a groove for incorporating one of the gears, and the other gear of the two gears on the outer periphery of the cylindrical member, and teeth at both axial ends of the other gear. A second step of forming different bottom circle diameters, and pushing the gear main body of the one gear into the outer periphery of the groove along the axial direction, and fixing the gear main body to the outer periphery of the groove by plastic flow. The above-mentioned problem is solved by including the third step of forming the one gear.

  According to the inventor's observation, in the gear structure in which two (or more) gears are formed adjacent to each other in the axial direction on the outer periphery of the cylindrical member, in particular, when at least one gear is formed by plastic coupling, particularly plastic coupling The gear (the other gear) adjacent to the gear to be moved tends to be inclined with respect to the axis of the cylindrical member due to the deformation of the cylindrical member.

  Based on this knowledge, the present invention forms at least the adjacent gears (the other gears) so that the root diameters at both ends in the axial direction are different. In other words, this means that the other gear is formed such that the pitch circle is different between one end side and the other end side in the axial direction (although the reference pitch and the module are unchanged). . That is, in the present invention, in anticipation that the other gear is inclined due to the deformation of the cylindrical member, the other gear is formed in a state of being reversely inclined in advance with respect to the cylindrical member.

  As a result, even if a part of the cylindrical member is deformed when it is plastically connected by pushing the gear body into the groove on the outer periphery of the cylindrical member with a strong load, the other gear is fixed correctly after "deformation". A state (formation state) can be maintained as a result, and a highly accurate gear structure can be manufactured.

  According to the present invention, when the gear of the gear structure is fixed by plastic flow, even if a part of the outer shape of the tubular member is deformed, the formation accuracy of the gear formed on the tubular member is maintained high. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS The manufacturing process in the manufacturing method of the gear structure which concerns on an example of embodiment of this invention is shown, (A) is sectional drawing which showed the gear blank before gear cutting, (B) is the gear main body after gear cutting. Sectional view of intermediate structure before pushing in, (C) is a sectional view of gear structure after pushing in the gear body The structure of the reduction gear device in which the gear structure to be manufactured by the above manufacturing method is incorporated is shown. (A) is an overall sectional view, (B) is a sectional view taken along IIB-IIB in (A), (C ) Is an IIC-IIC sectional view of (A), and (D) is an enlarged sectional view of the IID portion of (A). The manufacturing process in the manufacturing method of the conventional gear structure is shown, (A) is sectional drawing after pushing a gear main body after gear cutting, (B) is sectional drawing after pushing a gear main body.

  Hereinafter, an example of an embodiment of the present invention will be described in detail based on the drawings.

  FIG. 2 shows a reduction device for joint drive of an industrial robot in which a gear structure to be manufactured by a method for manufacturing a gear structure according to an example of the embodiment of the present invention is incorporated.

  2A is an overall cross-sectional view, FIG. 2B is a cross-sectional view taken along the line IIB-IIB in FIG. 2A, FIG. 2C is a cross-sectional view taken along the line IIC-IIC in FIG. FIG.

  The reduction gear G1 includes an input unit 12, a reduction ratio adjustment unit 14, and a main reduction mechanism unit 16.

  The input unit 12 is a portion that receives rotation from a motor (not shown). In this embodiment, the input unit 12 includes an input shaft 18 and a pinion 20 integrated with the input shaft 18.

  The reduction ratio adjustment unit 14 is configured by a gear structure 22.

  The gear structure 22 has a total of two gears, a first gear 26 and a second gear 28, formed adjacent to each other in the axial direction on the outer periphery of a hollow shaft (tubular member) 24. A more specific configuration of the gear structure 22 will be described in detail later when a method for manufacturing the gear structure 22 is described.

  The main reduction mechanism 16 is composed of a swinging intermeshing planetary gear mechanism. The main reduction mechanism unit 16 includes a third gear 30 that meshes with the first gear 26 of the gear structure 22 as an input gear. The third gear 30 is fixed to the eccentric body shaft 32. In FIG. 2, only one set of the third gear 30 and the eccentric body shaft 32 is depicted, but three sets of the third gear 30 and the eccentric body shaft 32 are actually arranged. Two eccentric bodies 34 are integrally formed on the eccentric body shaft 32, and an external gear 38 is assembled via rollers 36 so as to be eccentric (oscillating) and rotatable. The external gear 38 is in mesh with the internal gear 40. The internal gear 40 is integrated with the casing 42, and the number of teeth is slightly (for example, 1) more than the number of teeth of the external gear 38. The eccentric body shaft 32 is rotatably supported by a pair of first and second carriers 43 and 44 via tapered roller bearings 46 and 47. The first and second carriers 43 and 44 are integrated by a bolt 48 and are rotatably supported by the casing 42 via a pair of angular ball bearings 50 and 51.

  The operation of the main reduction mechanism 16 will be briefly described. For example, when the casing 42 (internal gear 40) is fixed, the external gear 38 is inscribed in the internal gear 40 by the rotation of the eccentric body shaft 32. It rotates slowly, and this rotation is taken out as revolution around the axis O1 of the eccentric body shaft 32, that is, rotation (rotation) of the first carrier 43 (and the second carrier 44). On the other hand, when the first carrier 43 (and the second carrier 44) is fixed, the revolution of the eccentric body shaft 32 is restricted, and the external gear 38 does not rotate (cannot). Therefore, the external gear 38 only swings while being inscribed in the internal gear 40 by the rotation (spinning) of the eccentric body shaft 32 constrained to revolve. By this swinging, the internal gear 40 rotates and the casing 42 integrated with the internal gear 40 rotates (so-called frame rotation).

  The reduction gear G1 according to this embodiment is incorporated into an industrial robot for driving its joint, and one of the casing 42 and the first carrier 43 is a member on the front arm side, and the other is a member on the rear arm side (whichever Are also fixed to each other). Thereby, a back | latter stage arm can be rotated relatively with respect to a front | former stage arm.

  In the present invention, the specific configuration of the device in which the gear structure is incorporated (in this embodiment, the reduction gear G1 in which the gear structure 22 is incorporated) is not particularly limited.

  Next, a detailed configuration of the gear structure 22 will be described.

  As described above, the gear structure 22 is formed by forming the first gear 26 and the second gear 28 adjacent to each other in the axial direction on the outer periphery of the hollow shaft (tubular member) 24. Of these, the first gear 26 is formed by plastic coupling of the gear body 26B to the basic teeth (grooves) 26A. Here, in this embodiment, since the “groove” for incorporating the first gear 26 is formed by gear cutting with the same tool as the second gear 28, it is referred to as “basic tooth 26 A”. The basic teeth 26A do not have to be so-called gear teeth, and may be grooves that allow the inner circumference of the first gear 26 to flow plastically. The gear body 26B is a ring-shaped member having a tooth portion 26B1 on the outer periphery and a hollow portion 26B2 in the center portion in the radial direction. The second gear 28 is formed integrally with the hollow shaft 24. The hollow shaft 24 is rotatably supported by a second carrier 44 and a member on the front stage (not shown) via a pair of bearings 25 and 27.

  In the gear structure 22 according to this embodiment, the second gear 28 meshes with the pinion 20 of the input unit 12, and the first gear 26 meshes with the third gear 30 that is the input shaft of the main reduction mechanism unit 16. ing. The engagement between the pinion 20 and the second gear 28 is “deceleration”, and the engagement between the first gear 26 and the third gear 30 is “speed increase”. By adjusting the number of teeth of each gear, particularly the first gear 26 (and the number of teeth of the third gear 30 meshing with the first gear 26), the reduction ratio of the entire reduction gear G1 can be adjusted.

  The gear structure 22 is manufactured as follows.

  First, as shown in FIG. 1A, a gear blank (material before gear cutting) 58 in which the first and second protrusions 54 and 56 are integrally formed is prepared. The first protrusion 54 has a height 54h corresponding to the tooth height 26h of the basic tooth 26A of the first gear 26, and an axial width 54w corresponding to the tooth width 26w of the basic tooth 26A. Here, the “tooth height of the basic tooth 26 </ b> A” corresponds to the height of the crest of the basic tooth (groove) 26 </ b> A, and specifically, the inner periphery of the hollow shaft 24 and the tooth tip (groove of the groove) of the basic tooth 26 </ b> A. It means the distance to the top of the mountain). The “tooth height of the basic tooth 26 </ b> A” may be defined as the distance from the axial center of the hollow shaft 24 to the tooth tip. Further, the second protrusion 56 has a height 56 h corresponding to the tooth height 28 h of the second gear 28 and an axial width 56 w corresponding to the tooth width 28 w of the second gear 28. The “tooth height of the second gear 28” corresponds to the height of the crest of the second gear 28, specifically, the inner circumference of the hollow shaft 24 and the teeth of the second gear 28, as described above. It means the distance to the destination. The “tooth height of the second gear 28” may also be defined as the distance from the axial center of the hollow shaft 24 to the tooth tip. A gap δ1 is provided between the first protrusion 54 and the second protrusion 56. The gap δ1 between the first and second protrusions 54 and 56 remains as a gap δ2 between the basic tooth 26A of the first gear 26 and the second gear 28 after gear cutting.

  As apparent from FIG. 1A, in this embodiment, the heights 54h and 56h of the first and second protrusions 54 and 56 are higher on the side where the gear body 26B is inserted. It is not constant in direction. As a result, the tooth heights 26h and 28h of the first and second gears 26 and 28 are also formed higher on the side where the gear body 26B is inserted. However, the slopes of the heights 54h and 56h of the first and second protrusions 54 and 56 are not directly related to “the root diameter is not constant in the axial direction” to be described later.

  Next, as shown in FIG. 1 (B), the basic teeth 26A of the first gear 26 are formed on the first protrusion 54 (first step), and the second tool is continuously used with the same tool as it is. A tooth portion of the second gear 28 is formed on the protrusion 56 (second step).

  At this time, at least the tooth portions of the second gear 28 are formed so that the root diameters 28d at both ends in the axial direction are different. That is, the root circle diameter on the first gear side of the second gear 28 is 28d1, the root circle diameter on the anti-first gear side is 28d2, and the root circle diameter 28d1 on the first gear side is Is larger (28d1> 28d2). This means that the reference pitch and the module are the same, but the pitch circle 28p increases toward the first gear.

  In this embodiment, the basic tooth 26A of the first gear 26 also has a root circular diameter (diameter at the bottom of the groove: that is, between the axis of the hollow shaft 24 and the bottom of the groove at both axial ends thereof. The distances 26d are different. In other words, in this embodiment, the root diameter on the anti-second gear side of the basic tooth 26A of the first gear 26 is 26d1, the root diameter on the second gear side is 26d2, and the anti-second The tooth root circle diameter 26d1 on the gear side is larger (26d1> 26d2).

  Further, as described above, in this embodiment, the base teeth 26A of the first gear 26 are caused by the fact that the heights 54h and 56h of the first and second protrusions 54 and 56 are not constant in the axial direction. The tooth height 26h of the second gear 28 and the tooth height 28h of the second gear 28 are not constant in the axial direction, and have inclinations along the inclinations of the root diameters 26d and 28d, respectively.

  In this embodiment, the tooth height 26h on the second gear 28 side of the basic tooth 26A of the first gear 26 is formed to be lower by Δh than the tooth height 28h on the first gear 26 side of the second gear 28. . The step portion 60 generated due to the tooth height difference Δh functions as a “stop portion” when the gear body 26B of the first gear 26 is pushed into the basic teeth 26A.

  The “intermediate structure 62” of the gear structure 22 in the state of FIG. 1B can be used as an intermediate product of the gear structure 22 and subject to inventory management (or distribution). This is because the gear structure 22 capable of adjusting various reduction ratios can be easily manufactured by appropriately selecting the gear body (26B) to be pushed in based on the intermediate structure 62.

  Finally, as shown in FIG. 1C, the gear body 26B of the first gear 26 is placed on the stepped portion 60 of the second gear 28 along the axial direction on the outer periphery of the basic tooth 26A of the first gear 26. A pushing load is applied until contact (third step). As a result, the gear body 26B can be fixed to the outer periphery of the basic tooth 26A by the coupling by plastic flow without backlash, and the formation of the first gear 26 by the plastic coupling is completed.

  In this embodiment, the following effects can be obtained by manufacturing the gear structure 22 having such a configuration by such a manufacturing method. Prior to this description, in order to facilitate understanding, a conventional gear structure or a problem occurring in the manufacturing method thereof will be described as a comparative example with reference to FIG. In FIG. 3, for the sake of convenience, the same reference numerals as those in FIG.

  Referring to FIG. 3A, in the conventional method of manufacturing the gear structure 22r, the tooth heights 26Ahr and 28hr of the basic teeth 26Ar and the second gear 28r of the first gear 26r, the pitch circles 26Apr, 28pr, Further, the root diameter 26Adr, 28dr and the like were the same at each position in the axial direction. Therefore, in this state, when the gear body 26Br of the first gear 26 is pushed and loaded along the axial direction on the outer periphery of the basic tooth 26Ar of the first gear 26r, a state as shown exaggerated in FIG. It is formed. That is, in particular, the second gear 28r formed adjacently (which is not plastically coupled) is directly affected by the deformation of the hollow shaft 24r, and the pitch circles 26Apr, 28pr, etc., which should be the same in the axial direction. Is inclined with respect to the axis O1. In this state, as a result, so-called one-side contact is generated in meshing between the second gear 28r and its counterpart gear (in the above embodiment, the pinion 20), and smooth power transmission is hindered.

  On the other hand, according to the manufacturing method of the gear structure 22 in the above embodiment, as shown in FIGS. 1A and 1B, the deformation of the hollow shaft 24 at the time of plastic coupling is assumed in advance, and the gear structure The second gear 28 is formed such that the root diameters 28d1 and 28d2 of the intermediate gear 62 of the second gear 28 are different at both axial ends of the second gear 28 (28d1> 28d2). Therefore, as shown in FIG. 1C, after plastic coupling, as a result, in addition to the pitch circle 28p of the second gear 28, the root circle diameter 28d, the tooth height 28h, and the like are also at respective positions in the axial direction. It can be made the same and can prevent the one piece contact.

  In the first gear 26, the pitch circle 26Bp can be kept the same at each position in the axial direction due to the rigidity of the gear body 26B (even if the hollow shaft 24 is slightly deformed). Both the first and second gears 26 and 28 can maintain a precise formation accuracy with respect to the hollow shaft 24 (the axial center O1 thereof).

  As is apparent from this function and effect, in the second step of the present invention, “the other gear (the second gear 28 in the embodiment) is formed to have different root diameters at the axial end portions”. Is intended to make the pitch circle of the second gear, in particular, the pitch circle of the second gear the same at each position in the axial direction after plastically coupling the gear body of the first gear.

  By using the gear structure 22 manufactured in this way, the number of teeth of the gear main body 26B of the first gear 26 and the number of teeth of the third gear 30 of the main reduction mechanism 16 that meshes with the gear main body 26B is appropriately set. By selecting this, the reduction ratio of the reduction gear G1 can be arbitrarily adjusted (within a certain range). Since both the first gear 26 and the second gear 28 are completely integrated with the hollow shaft 24 without backlash, the gear structure 22 is, for example, the speed reduction device G1 of the industrial robot exemplified in this embodiment. It is particularly suitable for applications that hate such backlash.

  In the present invention, the “groove” for incorporating “one gear (the first gear 26 in the embodiment)” to which the gear body is plastically coupled is not necessarily provided at both ends in the axial direction in advance at the stage of the intermediate structure. It is not required to manufacture so that the root diameter is different. This is because the gear that is plastically coupled can utilize the rigidity of the gear body itself, so that a pitch circle with a certain degree of accuracy can be maintained at each position in the axial direction even after plastic coupling. However, as shown in the above embodiment, in the present invention, it is not prohibited to adopt a configuration in anticipation of such deformation for the groove of the gear to be plastically coupled. In this case, as is apparent from the comparison of the depictions in FIGS. 3B and 1C, the effect that the plastic coupling between the groove and the gear body can be performed better is obtained.

  Moreover, in the said embodiment, it is comprised so that the tooth height of the 2nd gear side edge part of the basic gear (groove) of a 1st gear gear may be formed lower than the tooth height of the 1st gear wheel side edge part of a 2nd gear wheel. However, the stepped portion generated thereby functions as a stopping portion of the gear body at the time of plastic coupling in the third step. However, in the present invention, for example, a separate member that functions as a stopping portion can be used. If so, this configuration is not always necessary.

  Furthermore, in the above embodiment, the basic tooth (groove) in the first step and the tooth portion of the second gear in the second step are continuously processed with the same tool. The first step groove and the second gear tooth portion of the second step need not be continuously machined by the same tool, for example, in separate steps using different machining tools. It may be processed. When the tooth portions are separately formed in the independent process as described above, the deformation mechanism of the cylindrical member can be reflected more accurately, and as a result, a gear structure having higher formation accuracy can be obtained. it can.

  In the above-described embodiment, the second gear is used as it is as the second gear as it is in the cylindrical member. However, in the present invention, the second gear is used as a groove as the second gear. The gear body of the gear may be joined by plastic flow or may be fixed by other methods. That is, the “form a gear” in the present invention includes not only the direct formation on the cylindrical member but also a configuration in which a separate gear main body is fixed to the cylindrical member. Even in this case, after the second gear is formed (fixed), the same effect is obtained that the inclination of the second gear after the gear body of the first gear is plastically coupled can be reduced. Further, the groove (basic tooth 26A) is not limited to the one directly formed on the cylindrical member, and may be formed by fixing the ring-shaped member with the groove formed on the cylindrical member.

  Moreover, in the said embodiment, although the example in which only two gears of the 1st and 2nd gearwheel were formed in the cylindrical member was shown, in this invention, another gearwheel is further added to a cylindrical member. The present invention can also be applied when formed adjacent in the axial direction. In this case, the other gear may be designed out of the scope of the present invention, and the other gear is also formed as a “second gear of the present invention” with a design in consideration of the root diameter. You may do it.

G1 ... Deceleration device 12 ... Input unit 14 ... Reduction ratio adjustment unit 16 ... Main reduction mechanism unit 18 ... Input shaft 20 ... Pinion 22 ... Gear structure 24 ... Hollow shaft (tubular member)
26 ... 1st gear 26A ... Groove 26B ... Gear body 28 ... 2nd gear 28d1, 28d2 ... Tooth root circle diameter of axial direction end part of 2nd gear

Claims (5)

A method of manufacturing a gear structure, wherein at least two gears are formed adjacent to each other in the axial direction on the outer periphery of a cylindrical member,
Forming a groove for incorporating one of the two gears on the outer periphery of the cylindrical member; and
A second step of forming, on the outer periphery of the cylindrical member, the other gear of the two gears such that the root diameter at the axial end portions of the other gear is different;
A third step of forming the one gear by pushing the gear main body of the one gear along the axial direction into the outer periphery of the groove and fixing the gear main body to the outer periphery of the groove by plastic flow;
The manufacturing method of the gear structure characterized by including. In claim 1,
The groove in the first step is also formed such that the diameter of the bottom of the groove at both axial ends of the groove is different. In claim 1 or 2,
A gear structure characterized in that the height of the crest at the end on the other gear side of the groove is lower than the tooth height of the end on the one gear side of the other gear. Manufacturing method. The gear structure according to any one of claims 1 to 3, wherein the groove in the first step and the tooth portion of the other gear in the second step are continuously processed with the same tool. Manufacturing method. A gear having a first gear in which a gear body is coupled by plastic flow in a groove provided on an outer periphery of a cylindrical member, and a second gear formed adjacent to the first gear in the axial direction. An intermediate structure used to manufacture the structure,
An intermediate structure of a gear structure in which the groove and the second gear formed so as to have different root diameters at both axial ends are adjacent to each other in the axial direction.

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