Cases, gearboxes, robots

Abstract

To facilitate processing and enable reliable centering.SOLUTION: A case 210 for holding a shaft 226 via a main bearing 230 so as to be freely rotatable is constituted of two or more members 210A, 210B which are split in a direction of a spindle F0.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a case, a speed reducer, and a robot, and particularly to a technology suitable for use in a large-sized speed reducer. 【Background Art】 【0002】 In industrial robots, machine tools, etc., a large-sized speed reducer may be required. 【0003】 Patent Document 1 exemplifies a speed reducer including a case 2 provided with mounting holes 2b. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2018-009615 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2002-364717 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 In such a large-sized speed reducer, the machining of parts may become too large to exceed the machining limit of the current machining machine. In particular, when the axial dimension of the case becomes large, there is a risk that the machining of the mounting holes on the outer periphery cannot be performed. In that case, as a countermeasure, it is conceivable to divide the parts. A speed reducer with a divided case is described in Patent Document 2. 【0006】 However, as described in Patent Document 2, simply dividing the parts does not enable centering required for the speed reducer during assembly. For this reason, there is a problem that a jig for assembly enabling centering needs to be prepared, or the work during assembly becomes too complicated and is not practical. 【0007】 While it might be conceivable to manufacture machining equipment capable of handling larger speed reducers, in reality, machining equipment that can meet the required machining precision and other conditions for manufacturing speed reducers is not readily available. 【0008】 The present invention aims to achieve the objective of enabling the manufacture of large-scale speed reducers and the like using existing processing machines. [Means for solving the problem] 【0009】 One aspect of the present invention is a case that rotatably holds a shaft via a main bearing, It consists of two or more members that are divided in the direction of the main axis. 【0010】 According to one aspect of the present invention, in each part of the divided case, the dimension in the direction of the main axis becomes smaller than in the case without division. This allows for reducing the dimensions to be processed, making it possible to perform the processing using a machining center. 【0011】 It has a first case and a second case, The first case may have a stepped portion into which the main bearing is fitted. 【0012】 The outer ring of the main bearing can be used to position the second case. 【0013】 In the direction of the main bearing, the division position on the inner circumferential surface can coincide with the main bearing. 【0014】 The main bearing can be divided into three sections in the direction of the main axis, and a pair of main bearings can be arranged in the direction of the main axis. 【0015】 It is roughly cylindrical in shape, and its outer circumference may be provided with mounting grooves that extend parallel to the main axis direction. 【0016】 The mounting groove can be fastened by a fastening member. 【0017】 A speed reducer according to another aspect of the present invention includes a shaft, a main bearing, a case that rotatably holds the shaft via the main bearing, and the case is composed of two or more members divided in the main shaft direction and contacting the outside of the shaft from the main bearing. 【0018】 According to the speed reducer according to another aspect of the present invention, in each part of the divided case, the dimension in the main shaft direction is smaller than that in the case of not dividing. Thereby, the dimensions of the parts to be processed can be reduced, enabling processing by a processing machine. In particular, the ease can be increased for processing performed by operating the processing machine in the main shaft direction. 【0019】 the case has a first case and a second case, the first case can have a stepped portion into which the main bearing fits. 【0020】 The positioning of the second case can be performed by the outer ring of the main bearing. 【0021】 In the main shaft direction, the division position on the inner peripheral surface of the case and the main bearing can coincide. 【0022】 The case is divided into three parts in the main shaft direction, and a pair of the main bearings can be arranged in the main shaft direction. 【0023】 The case is substantially cylindrical, and can be provided with a mounting groove extending parallel to the main shaft direction on the outer periphery. 【0024】 The case can be fastened by a fastening member that fastens the mounting groove. 【0025】 A robot according to another aspect of the present invention includes the speed reducer according to any one of the above descriptions, a drive unit, A driven part that is driven by the driving force transmitted from the drive unit via the reduction gear, It is equipped with. 【0026】 According to one aspect of the present invention, the divided case of the reduction gear has a smaller dimension in the direction of the main axis in each part compared to when it is not divided. This allows for reducing the dimensions of the parts to be processed, making it possible to process them using a machining center. In particular, it increases the ease of processing when the machining center is operated in the direction of the main axis. [Effects of the Invention] 【0027】 According to the present invention, it becomes possible to easily process and manufacture cases using existing processing machines, thus achieving the desired effect. [Brief explanation of the drawing] 【0028】 [Figure 1] This is a cross-sectional view along the axial direction showing a first embodiment of the speed reducer according to the present invention. [Figure 2] This is an axial view of the first embodiment of the case according to the present invention. [Figure 3] This is an enlarged cross-sectional view of the first embodiment of the case according to the present invention. [Modes for carrying out the invention] 【0029】 Hereinafter, a first embodiment of the case, reducer, and robot according to the present invention will be described with reference to the drawings. Figure 1 is a cross-sectional view along the axial direction showing the gearbox in this embodiment, and Figure 2 is an end view of the gearbox in the axial direction showing the gearbox in this embodiment. In the figures, reference numeral 100 denotes the gearbox. 【0030】 As shown in Figures 1 to 3, the reduction gear 100 according to this embodiment comprises a housing cylinder 200, a gear section (external tooth member) 300, and three crank assemblies 400. The housing cylinder 200 houses the gear section 300 and the three crank assemblies 400. In this embodiment, the speed reducer 100 is an eccentric oscillating speed reducer. 【0031】 The housing cylinder 200 includes a case (outer cylinder portion) 210, a carrier portion (carrier) 220, and two main bearings 230. The carrier portion 220 is located inside the case (outer cylinder portion) 210. The two main bearings 230 are located between the case (outer cylinder portion) 210 and the carrier portion 220. The two main bearings 230 enable relative rotational motion between the case (outer cylinder portion) 210 and the carrier portion 220. In this embodiment, the output section of the reducer 100 is exemplified by either the case (outer cylinder portion) 210 or the carrier portion 220. 【0032】 Figure 1 shows the central axis (main shaft) F0 of the reducer 100, which is defined as the rotational axis of the two main bearings 230. When the case (outer cylinder) 210 is fixed, the carrier 220 rotates around the main shaft F0. When the carrier 220 is fixed, the case (outer cylinder) 210 rotates around the main shaft F0. That is, one of the case (outer cylinder) 210 and the carrier 220 can rotate relative to the other of the case (outer cylinder) 210 and the carrier 220 around the main shaft F0. In this embodiment, the direction along the central axis (main shaft) F0 of the reduction gear 100, which serves as the rotational axis of the two main bearings 230, is referred to as the axial direction. 【0033】 The cylindrical case (outer cylinder) 210 is divided in the direction of the main shaft F0 and consists of three roughly cylindrical parts: the first case 210A, the second case 210B, and the third case 210C. The first case 210A, the second case 210B, and the third case 210C all have the same diameter and are arranged so that they share the same spindle F0 as their axis. Furthermore, they are assembled in the order of second case 210B, first case 210A, and third case 210C in the direction of spindle F0. 【0034】 The case (outer cylinder portion) 210 includes an outer cylinder 211 and a plurality of internal tooth pins (internal teeth) 212. The outer cylinder 211 defines a cylindrical internal space in which the carrier portion 220, the gear portion 300, and the crank assembly 400 are housed. Each internal tooth pin 212 is a cylindrical member extending substantially parallel to the main shaft F0. Each internal tooth pin 212 is fitted into a groove formed in the inner wall of the outer cylinder 211. Thus, each internal tooth pin 212 is properly held by the outer cylinder 211. 【0035】 Multiple internal tooth pins 212 are arranged at approximately constant intervals around the main spindle F0. The half-circumferential surface of each internal tooth pin 212 protrudes from the inner wall of the outer cylinder 211 toward the main spindle F0. Therefore, the multiple internal tooth pins 212 function as internal teeth that mesh with the gear section 300. The inner wall of the first case 210A has grooves formed in the outer cylinder 211 into which each internal tooth pin 212 is fitted. The second case 210B and the third case 210C are designed so that the internal tooth pins 212 do not come into contact with each other. 【0036】 The second case 210B and the third case 210C are combined with the first case 210A in the outward direction along the spindle F0. The dividing surface of case 210, that is, the contact surface between the first case 210A and the second case 210B, is aligned at least in a direction perpendicular to the spindle F0. The contact surface between the first case 210A and the third case 210C is aligned at least in a direction perpendicular to the spindle F0. A sealing portion 211s, consisting of a sealing member such as an O-ring and a sealing groove, is formed around the entire circumference of the main shaft F0 on the contact surface between the first case 210A and the second case 210B. A sealing portion 211s, consisting of a sealing member such as an O-ring and a sealing groove, is formed around the entire circumference of the main shaft F0 on the contact surface between the first case 210A and the third case 2103. 【0037】 The division point on the inner circumferential surface of case 210 is in contact with the main bearing 230. In other words, in the direction along the main shaft F0, the division point on the inner circumferential surface of case 210 and the main bearing 230 coincide. That is, on the inner circumferential surface of case 210, the outer circumference of one main bearing 230 is in contact with the boundary position between the first case 210A and the second case 210B. Also, on the inner circumferential surface of case 210, the outer circumference of the other main bearing 230 is in contact with the boundary position between the first case 210A and the third case 210C. 【0038】 On the inner circumferential surface of the first case 210A, stepped portions 211b and 211c are formed corresponding to the ends of the main bearing 230 in the direction along the main shaft F0. A main bearing 230, which contacts the second case 210B, is fitted into the stepped portion 211b. The main bearing 230, which contacts the third case 210C, is fitted into the stepped portion 211c. In the direction along the main spindle F0, the inner circumference of the first case 210A is configured to have a smaller diameter in the portion between the stepped portion 211b and the stepped portion 211c. 【0039】 As shown in Figure 2, a flange portion (mounting flange) 215 is provided around the outer circumference of the cylindrical case (outer cylinder portion) 210. Multiple mounting holes (mounting grooves) 216 are formed on the periphery of the flange portion 215, extending in the direction along the main shaft F0. The mounting holes (mounting grooves) 216 are spaced apart from each other in the circumferential direction of the flange portion 215. The flange portion 215 is used when attaching the case 210 of the reduction gear 100 to a robot or the like, which will be described later. 【0040】 Furthermore, the flange portion 215 is used when assembling the first case 210A, the second case 210B, and the third case 210C. The first case 210A is provided with a flange portion 215A around its circumference. The second case 210B is provided with a flange portion 215B around its circumference. The third case 210C is provided with a flange portion 215C around its circumference. 【0041】 Flange portion 215A and flange portion 215B are in contact with the dividing surface of the case (outer cylinder portion) 210. Flange portion 215A and flange portion 215C are in contact with the dividing surface of the case (outer cylinder portion) 210. 【0042】 In this embodiment, the mounting hole (mounting groove) 216 is formed as a through hole that penetrates along the main shaft F0, but it can also be formed as a groove that opens in the outer circumferential direction of the case 210. A large-diameter bolt (fastening member) B1 is installed in the mounting hole (mounting groove) 216 in a direction along the main axis F0, and the large-diameter bolt (fastening member) B1 fastens the first case 210A, the second case 210B, and the third case 210C. 【0043】 The mounting holes (mounting grooves) 216 are located in the same positions in the first case 210A, the second case 210B, and the third case 210C when viewed in the direction along the spindle F0. Specifically, the first case 210A has a mounting hole (mounting groove) 216A extending along the spindle F0. The second case 210B has a mounting hole (mounting groove) 216B extending along the spindle F0. The third case 210C has a mounting hole (mounting groove) 216C extending along the spindle F0. 【0044】 Mounting holes (mounting grooves) 216A, 216B, and 216C are all of the same diameter. Mounting holes (mounting grooves) 216A, 216B, and 216C are positioned so that their axes align when the case 210 is assembled. 【0045】 As shown in Figure 2, temporary fixing holes 216E are formed in the flange portion (mounting flange) 215 of the case (outer cylinder portion) 210 at positions between the mounting holes (mounting grooves) 216 in the circumferential direction. The temporary fastening holes 216E are used to temporarily fasten the first case 210A, the second case 210B, and the third case 210C when assembling the case 210 and the carrier section 220. 【0046】 The temporary fixing holes 216E are smaller in diameter than the mounting holes (mounting grooves) 216, and the first case 210A, the second case 210B, and the third case 210C are temporarily fixed with small temporary fixing bolts (fastening members) B2 (see Figure 2). The temporary fastening hole 216E of the first case 210A is a through hole. The temporary fastening hole 216E of the second case 210B, or the temporary fastening hole 216E of the third case 210C, has a female threaded portion that corresponds to the male threaded portion at the tip of the temporary fastening bolt (fastening member) B2. The first case 210A, the second case 210B, and the third case 210C are temporarily fastened together by the temporary fastening bolt (fastening member) B2. 【0047】 Furthermore, as shown in Figure 2, a suspension ring 216D is formed on the flange portion (mounting flange) 215 of the case (outer cylinder portion) 210 at a position between the mounting holes (mounting grooves) 216 in the circumferential direction. At the inner circumference end of the second case 210B, a sealing member 210s is positioned between it and the carrier portion 220, and is located outside the main bearing 230, around the entire circumference of the main shaft F0. 【0048】 As shown in Figures 1 and 3, the main bearing 230 has balls 231, an inner race 232, and an outer race 233. The inner race (inner ring) 232 has its inner circumference in contact with the carrier portion 220. The inner race (inner ring) 232 has its inner circumference fitted into the stepped portions 221b and 221c of the base (first member) 221. Alternatively, the corners of the inner race (inner ring) 232 are embedded in the stepped portion 222c of the end plate (hold) 222. The outer race (outer ring) 233 has its outer circumference in contact with the case 210. The outer race (outer ring) 233 is fitted into the stepped portions 211b and 211c of the first case 210A. 【0049】 The outer circumferential surfaces of the outer race (outer ring) 233 are in contact with the inner circumferential surfaces of the stepped portions 211b and 211c of the first case 210A, respectively. The outer surface of the outer race (outer ring) 233 is in contact with the inner surface of the second case 210B and the inner surface of the third case 210C, respectively. The surfaces of the outer race (outer ring) 233 that are close to the gear portion 300 are in contact with the stepped portions 211b and 211c of the first case 210A, respectively. 【0050】 In this way, the outer race (outer ring) 233 is in contact with the stepped portions 211b and 211c of the first case 210A, the inner circumferential surface of the second case 210B, and the inner circumferential surface of the third case 210C, respectively, allowing the first case 210A, the second case 210B, and the third case 210C to be assembled concentrically and centered. 【0051】 The carrier section 220 includes a base (first member) 221, an end plate (second member) 222, a positioning pin 223, and a support bolt (fixing bolt) 224. The carrier section 220 has an overall cylindrical shape. A through hole is formed in the carrier section 220 that is concentric with the main shaft F0. 【0052】 The base (first member) 221 includes a substrate portion 225 and three shaft portions (shafts) 226. Each of the three shaft portions 226 extends from the substrate portion 225 toward the end plate portion (second member) 222. Screw holes 227 and reamer holes are formed on the tip surface of each of the three shaft portions 226. Positioning pins are inserted into the reamer holes. As a result, the end plate portion (second member) 222 is precisely positioned relative to the base (first member) 221. In the base portion (first member) 221, a mounting hole 228 is formed on the end face opposite to that of the end plate portion (second member) 222. 【0053】 The support bolt 224 is fastened into the screw hole 227. As a result, the end plate portion (second member) 222 is properly fixed to the base portion (first member) 221. The base (first member) 221 and the end plate (second member) 222 are fixed together by the support bolts 224 so that they are concentric. The end plate (second member) 222 is called a hold. 【0054】 The gear section 300 is positioned between the base plate section 225 and the end plate section (second member) 222. The three shaft sections 226 pass through the gear section 300 and are connected to the end plate section (second member) 222. 【0055】 The gear section 300 includes two gears 310 and 320. Gear 310 is positioned between the base plate section 225 and gear 320. Gear 320 is positioned between the end plate section (second member) 222 and gear 310. 【0056】 Gear 310 is approximately identical to gear 320 in shape and size. Gears 310 and 320 rotate around the outer cylinder 211 while meshing with the internal tooth pin 212. Therefore, the centers of gears 310 and 320 rotate around the main shaft F0. 【0057】 The rotational phase of gear 310 is shifted by approximately 180° from the rotational phase of gear 320. Gear 310 meshes with half of the internal tooth pins 212 of the case (outer cylinder portion) 210, while gear 320 meshes with the remaining half of the internal tooth pins 212. Therefore, the gear portion 300 can rotate the case (outer cylinder portion) 210 or the carrier portion 220. 【0058】 In this embodiment, the gear section 300 includes two gears 310 and 320. Alternatively, the gear section may use more than two gears. Furthermore, alternatively, the gear section may use one gear. 【0059】 Each of the three crank assemblies 400 includes a crankshaft 410, four bearings 421, 422, 423, and 424, and a transmission gear (external teeth) 430. The transmission gear 430 may be a general spur gear. In the reduction gear 100 of this embodiment, the transmission gear 430 is not limited to a particular type. 【0060】 The transmission gear 430 receives the driving force generated by the drive source (e.g., a motor) directly or indirectly. The reduction gear 100 can appropriately set the transmission path of the driving force from the drive source to the transmission gear 430 according to its operating environment and conditions. Therefore, this embodiment is not limited to a specific drive transmission path from the drive source to the transmission gear 430. 【0061】 Figure 1 shows the crank axis (transmission axis) F2. The transmission axis F2 is approximately parallel to the main shaft F0. The crankshaft 410 rotates around the transmission axis F2. The crankshaft 410 includes two journals (crank journals) 411, 412 and two eccentric sections (eccentric bodies) 413, 414. The journals 411, 412 extend along the transmission shaft F2. The central axes of the journals 411, 412 coincide with the transmission shaft F2. The eccentric sections 413, 414 are formed between the journals 411, 412. Each of the eccentric sections 413, 414 is eccentric from the transmission shaft F2. 【0062】 Journal 411 is inserted into bearing 421. Bearing 421 is positioned between journal 411 and end plate portion (second member) 222. Therefore, journal 411 is supported by end plate portion (second member) 222 and bearing 421. Journal 412 is inserted into bearing 422. Bearing 422 is positioned between journal 412 and base portion (first member) 221. Therefore, journal 412 is supported by base portion (first member) 221 and bearing 422. 【0063】 In this embodiment, bearing 421 is a needle bearing, with a plurality of rollers 431, an inner race 411a, and an outer race 411b arranged around the journal 411. Bearing 422 is a needle bearing, with a plurality of rollers 432, an inner race 412a, an outer race 412b, and a journal 412 arranged around the journal 412. 【0064】 The eccentric portion 413 is inserted into the bearing 423. The bearing 423 is positioned between the eccentric portion 413 and the gear 310. The eccentric portion 414 is inserted into the bearing 424. The bearing 424 is positioned between the eccentric portion 414 and the gear 320. In this embodiment, bearing 423 is a needle bearing, with a plurality of rollers 433 arranged around the eccentric portion (eccentric body) 413. Bearing 424 is a needle bearing, with a plurality of rollers 434 arranged around the eccentric portion (eccentric body) 414. 【0065】 When a driving force is applied to the transmission gear 430, the crankshaft 410 rotates around the transmission shaft F2. As a result, the eccentric parts 413 and 414 rotate eccentrically around the transmission shaft F2. The gears 310 and 320, connected to the eccentric parts 413 and 414 via bearings 423 and 424, oscillate within the circular space defined by the case (outer cylinder) 210. Since the gears 310 and 320 mesh with the internal tooth pins 212, a relative rotational motion is caused between the case (outer cylinder) 210 and the carrier 220. 【0066】 In the gearbox 100 according to this embodiment, as shown in Figures 1 to 3, the case (outer cylinder) 210 is divided in the direction of the main shaft F0 and consists of a first case 210A, a second case 210B, and a third case 210C. Steps 211b and 211c are formed on the inner circumferential surface of the first case 210A. The outer race (outer ring) 233 of the main bearing 230 is in contact with the steps 211b and 211c of the first case 210A, the inner circumferential surface of the second case 210B, and the inner circumferential surface of the third case 210C, respectively. 【0067】 Furthermore, in the direction of the main shaft F0, the main bearing 230 covers the dividing line on the inner circumferential surface of case 210. In other words, the dividing line on the inner circumferential surface of case 210 coincides with the main bearing 230. Specifically, the outer circumference of the outer race (outer ring) 233 of the main bearing 230 is in contact with the boundary between the first case 210A and the second case 210B. Also, the outer circumference of the outer race (outer ring) 233 of the main bearing 230 is in contact with the boundary between the first case 210A and the third case 210C. 【0068】 The dimensions of the first case 210A in the spindle F0 direction are smaller than the dimensions of the first case 210 in the spindle F0 direction. The dimensions of the second case 210B in the spindle F0 direction are smaller than the dimensions of the second case 210 in the spindle F0 direction. The dimensions of the third case 210C in the spindle F0 direction are smaller than the dimensions of the second case 210 in the spindle F0 direction. 【0069】 Therefore, in the manufacturing process of the reducer 100, the dimensions of each part of the divided case 210 in the direction of the main shaft F0 can be made smaller compared to when it is not divided. As a result, the dimensions of each of the first case 210A, second case 210B, and third case 210C to be machined are small, making it possible to machine each of them using a machining center. In particular, it is possible to increase the ease of machining when the machining center is operated in the direction of the main spindle F0. 【0070】 In particular, it will be possible to perform the machining of a mounting hole (mounting groove) 216A extending along the spindle F0 in the first case 210A using the current machining equipment. Similarly, it will be possible to perform the machining of a mounting hole (mounting groove) 216B extending along the spindle F0 in the second case 210B using the current machining equipment. It will also be possible to perform the machining of a mounting hole (mounting groove) 216C extending along the spindle F0 in the third case 210C using the current machining equipment. 【0071】 This configuration allows the first case 210A, the second case 210B, and the third case 210C to be assembled concentrically and centered. At the same time, the case (outer cylinder) 210 and the carrier (carrier) 220 can be assembled concentrically and centered. In other words, by providing stepped sections 211b and 211c, the main bearing 230 fits into the first case 210A, enabling centering. In other words, the outer race (outer ring) 233 of the main bearing 230 can be used to position the second case 210B. Similarly, the outer race (outer ring) 233 of the main bearing 230 can be used to position the third case 210C. 【0072】 Because the division position on the inner circumferential surface of case 210 coincides with the main bearing 230, the centering of the first case 210A, the second case 210B, and the third case 210C can be performed using the outer race (outer ring) 233 of the main bearing 230. 【0073】 Since the case 210 is divided into three sections in the direction of the main spindle F0, and a pair of main bearings 230 are arranged in the direction of the main spindle F0, the centering of the first case 210A, the second case 210B, and the third case 210C can be performed using the outer race (outer ring) 233 of the main bearing 230. 【0074】 The case 210 is roughly cylindrical, with flange portions 215A, 215B, and 215C on its outer circumference in contact with each other. Mounting holes (mounting grooves) 216A, 216B, and 216C are formed parallel to the direction of the main axis F0, and these can be fastened by passing large-diameter bolts (fastening members) B1 through them, allowing the first case 210A, the second case 210B, and the third case 210C to be assembled in a centered state. By fastening the mounting grooves 216A, 216B, and 216C with large-diameter bolts (fastening members) B1, the case 210 can be assembled concentrically. At the same time, in this state, the case (outer cylinder part) 210 and the carrier part (carrier) 220 can be assembled concentrically and centered. 【0075】 The gearbox 100 according to this embodiment can, for example, have a diameter larger than 50 mm. 【0076】 In the gearbox 100 according to this embodiment, for example, the spindle F0 dimension of the first case 210A is larger than the spindle F0 dimension of the second case 210B. The spindle F0 dimension of the first case 210A is larger than the spindle F0 dimension of the third case 210C. The spindle F0 dimension of case 1 210A is greater than the sum of the spindle F0 dimension of case 2 210B and the spindle F0 dimension of case 3 210C. The sum of the spindle F0 dimension of the second case 210B and the spindle F0 dimension of the third case 210C may be less than half of the spindle F0 dimension of the first case 210A. 【0077】 The alignment and assembly method of the gearbox 100 in this embodiment will be described. 【0078】 First, a base (first member) 221 equipped with a shaft portion 226 is prepared. In the alignment and assembly method of the reduction gear 100, specific parts, jigs, etc. can be used to support and hold each member, but these will not be explained here. 【0079】 Next, the inner race (inner ring) 232 of the main bearing 230 is fitted onto the outer circumference of the base (first member) 221. At this time, the corners of the inner race (inner ring) 232 come into contact with the stepped portion 221b of the base (first member) 221. As a result, the base (first member) 221 and the inner race (inner ring) 232 become concentric with respect to the main shaft F0. 【0080】 Next, multiple balls 231 are placed in the inner race 232. Then, the outer race 233 is assembled to the balls 231 to complete the main bearing 230 at the position in contact with the second case 210B. At this time, the base (first member) 221 and the outer race 233 are concentric with respect to the main shaft F0. Also, the base (first member) 221 and the main bearing 230 are concentric with respect to the main shaft F0. 【0081】 Next, the second case 210B is fitted onto the outer circumference of the main bearing 230, which is fitted onto the base (first member) 221. The inner circumference of the second case 210B contacts the outer race (outer ring) 233. 【0082】 Next, the first case 210A is fitted onto the outer circumference of the main bearing 230 fitted to the base (first member) 221 so as to be coaxial with the second case 210B. At this time, the inner circumference of the end of the first case 210A contacts the outer race (outer ring) 233. Simultaneously, the corner of the outer race (outer ring) 233 abuts against the stepped portion 211b of the first case 210A. The stepped portion 211b causes the first case 210A and the outer race 233 to be concentric with respect to the spindle F0. At the same time, the stepped portion 211b positions the first case 210A and the outer race 233 in the direction along the spindle F0. Furthermore, in the first case 210A, a sealing member such as an O-ring can be inserted in advance into the sealing groove of the sealing portion 211s on the surface that contacts the second case 210B. 【0083】 Next, the outer race 233, positioned to contact the third case 210C, is fitted into the stepped portion 211c of the first case 210A. At this time, the outer race 233, positioned to contact the third case 210C, may be fitted into the stepped portion 211c of the first case 210A in advance, and then fitted onto the outer circumference of the main bearing 230, which has the first case 210A fitted to the base (first member) 221. The stepped portion 211c ensures that the first case 210A and the outer race 233 are concentric with respect to the spindle F0. At the same time, the stepped portion 211c positions the first case 210A and the outer race 233 in the direction along the spindle F0. In other words, the stepped portions 211b and 211c position the first case 210A and the base (first member) 221 in a direction along the main axis F0. 【0084】 Next, the third case 210C is fitted onto the outer circumference of the outer race 233, which is fitted onto the stepped portion 211c of the first case 210A, so that it is coaxial with the first case 210A. At this time, the inner circumference of the end of the third case 210C is in contact with the outer race 233. Furthermore, in the first case 210A, a sealing member such as an O-ring can be inserted in advance into the sealing groove of the sealing portion 211s on the surface that contacts the third case 210C. 【0085】 Next, multiple balls 231 are placed in the outer race 233. Then, the inner race 232 is assembled onto the balls 231 to complete the main bearing 230 at the position where it contacts the third case 210C. At this time, The corner of the inner race (inner ring) 232 abuts against the stepped portion 222c of the end plate (hold) 222. As a result, the third case 210C, the base (first member) 221, and the inner race (inner ring) 232 are concentric with respect to the main spindle F0. Also, the third case 210C, the base (first member) 221, and the main bearing 230 are concentric with respect to the main spindle F0. 【0086】 At this time, the inner race (inner ring) 232 and the end plate (hold) 222 are pre-assembled together and then fitted into the base (first member) 221. 【0087】 Before assembling the end plate portion (hold) 222, the internal tooth pins 212, gear portion 300, crank assembly 400, etc. can be pre-assembled into the base portion (first member) 221 to form a shaft assembly. 【0088】 At this time, the end plate portion (hold) 222 and the inner race (inner ring) 232, and the base portion (first member) 221 and the outer race (outer ring) 233 are concentric with respect to the main spindle F0. Also, the third case 210C, the carrier portion 220, and the main bearing 230 are concentric with respect to the main spindle F0. 【0089】 In this state, the support bolt 224 is fastened into the screw hole 227. As a result, the end plate portion (second member) 222 is fixed to the base portion (first member) 221. At this time, the base (first member) 221 and the end plate (second member) 222 are fixed together by the support bolts 224, making them concentric. 【0090】 In this state, temporary fastening bolts (fastening members) B2 are passed through the temporary fastening holes 216E of the first case 210A, the second case 210B, and the third case 210C and fastened to them, thereby temporarily fastening the first case 210A, the second case 210B, and the third case 210C. This completes the alignment and assembly of the case (outer cylinder) 210, the carrier section (carrier) 220, and the two main bearings 230. At this time, it is not necessary to install the large-diameter bolts (fastening members) B1 in the mounting holes (mounting grooves) 216. Furthermore, necessary assembly processes are performed, such as fitting the sealing member 210s between the carrier portion 220 and the inner circumference end of the second case 210B, outside of the main bearing 230. 【0091】 For example, the reduction gear 100 can be transported for connection to the drive system of a robot or the like with all necessary parts assembled except for the large-diameter bolt (fastening member) B1. 【0092】 Furthermore, a large-diameter bolt (fastening member) B1 is passed through the mounting hole (mounting groove) 216, and the first case 210A, the second case 210B, and the third case 210C are assembled concentrically, and the reduction gear 100 is attached to a robot or the like. At this time, the mounting hole 228 can be used to mount the reduction gear 100. After this, the temporary fastening bolt (fastening member) B2 can be removed. 【0093】 This completes the alignment and assembly of the gearbox 100 in this embodiment. 【0094】 Among the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective. [Explanation of symbols] 【0095】 100...Reducer 210...Case (outer cylinder part) 210A…Case 1 210B…Case 2 210C…Case 3 215...Flange section (mounting flange) 216…Mounting holes (mounting grooves) 220…Career Department (Career) 221...Base (first member) 222...End plate section (second member) 224... Support bolt (fixing bolt) 230…Main bearing 232... Inner lace (inner lining) 233...Outer race (outer ring) B1... Bolt (fastening component) F0…Center axis (main axis)

Claims

[Claim 1] A case that rotatably holds a plurality of shafts provided on a carrier portion via two main bearings, The aforementioned case is composed of a first case, a second case, and a third case, which are divided in the direction of the main axis and are in contact with the main bearing on the outside of the shaft. In the direction of the main axis, the division position on the inner circumferential surface of the first case and the second case coincides with the main bearing, and the division position on the inner circumferential surface of the first case and the third case coincides with the main bearing, The step portion in the first case into which the main bearing is fitted allows the outer ring of the main bearing to position the second case. The step portion in the first case into which the main bearing is fitted allows the outer ring of the main bearing to position the third case. The carrier portion is positioned by the inner ring of the main bearing through the stepped portion into which the main bearing fits, provided on the carrier portion. The first case, the second case, the third case, and the carrier section can be centered. reducer. [Claim 2] The gearbox according to claim 1, wherein the case is substantially cylindrical and has a mounting groove on its outer circumference that extends parallel to the direction of the main axis. [Claim 3] The gearbox according to claim 2, wherein the case is fastened by a fastening member that fastens the mounting groove. [Claim 4] A flange portion is provided around the outer circumference of the case, The reduction gear according to claim 2, wherein a suspension ring is formed on the flange portion. [Claim 5] The gearbox according to claim 1, The drive unit and A robot comprising a driven part that is driven by a driving force transmitted from the drive unit via the reduction gear.