Work assembly device

Abstract

To provide a workpiece assembly device which can hold a workpiece to be assembled to an assembly object properly despite having a compact and simple structure.SOLUTION: A workpiece assembly device 1 includes a holding part 11 for holding a workpiece (a lash adjuster 20). In the holding part 11, a cylindrical body 13 in which a workpiece is inserted into an inner periphery and a holding ring 14 which is annularly formed by an elastic material and fits in an outer periphery of the cylindrical body 13 with its diameter elastically expanding are provided. Cutouts 13e for allowing the holding ring 14 to partially protrude into the inner periphery of the cylindrical body 13 are provided at a portion, in which the holding ring 14 is fitted, of the cylindrical body 13. The workpiece is held by protruding parts 14a, which protrude into the inner periphery of the cylindrical body 13, of the holding ring 14.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a workpiece assembly device. [Background technology]

[0002] A known valve train for an internal combustion engine, such as an automobile engine, includes a cam connected to a camshaft, a rocker arm pressed by the cam, and a lash adjuster supporting one end of the rocker arm. In this valve train, the lash adjuster is assembled to a recess provided in the cylinder block.

[0003] Patent Document 1 listed below discloses a workpiece assembly device used when assembling a workpiece such as a lash adjuster to an assembly target. This workpiece assembly device includes a holding unit that holds the workpiece and a push-out unit that moves coaxially with the holding unit relative to the holding unit to push the workpiece held by the holding unit outward and assemble it to the assembly target. As described in paragraphs 0022-0023 and Figure 2 of the document, the holding unit includes a cylindrical body into whose inner periphery the workpiece is inserted, holding pins that are arranged at intervals at multiple locations (e.g., two locations) around the circumference of the cylindrical body and hold the workpiece at their tip ends, and pin biasing means that biases the holding pins radially inward so that their tip ends protrude into the inner periphery of the cylindrical body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-190215 Summary of the Invention [Problem to be solved by the invention]

[0005] In the workpiece assembly device of Patent Document 1, the retaining pins, which are spaced apart at two locations around the circumference of the cylindrical body, and the pin biasing means that bias the retaining pins radially inward are arranged in a row along the diameter of the cylindrical body, necessitating the use of a cylindrical body that is thick in the radial direction. As a result, it is difficult to use the workpiece assembly device of Patent Document 1, for example, when assembling a lash adjuster as a workpiece into a recessed portion provided in a recessed position of a cylinder block to which it is to be assembled. Therefore, the workpiece assembly device of Patent Document 1 is inevitably limited in its uses and has low versatility.

[0006] Furthermore, in the workpiece assembly device of Patent Document 1, the workpiece slides against the holding pins when it is attached to the holding part and when it is separated from the holding part (when the workpiece is assembled to the assembly target), so repeated use of the device can cause the holding pins to wear out and reduce the holding force of the workpiece. For this reason, the holding pins need to be replaced periodically, but because the holding pins are arranged at multiple locations around the circumference of the cylindrical body and pin biasing means for biasing the holding pins are also arranged on the cylindrical body, replacing the holding pins (maintenance work for the holding part) requires time and cost.

[0007] The present invention has been made to solve various problems associated with known work assembly devices (holding units), and its main purpose is to realize a holding unit that is compact and simple in configuration yet can properly hold a work to be assembled to an assembly target, thereby contributing to improving the versatility and maintainability of the work assembly device. [Means for solving the problem]

[0008] The present invention, which was invented to achieve the above object, provides a workpiece assembly device including a holding unit that holds a workpiece and a pusher that moves coaxially with the holding unit relative to the holding unit to push out the workpiece held in the holding unit and assemble it to an assembly target. The holding unit includes a cylindrical body into whose inner periphery the workpiece is inserted, and a retaining ring made of an elastic material and fitted around the outer periphery of the cylindrical body in an elastically expanded state. The portion of the cylindrical body into which the retaining ring is fitted has a notch that allows the retaining ring to partially protrude into the inner periphery of the cylindrical body, and the workpiece is held by the protruding portion of the retaining ring that protrudes into the inner periphery of the cylindrical body. The "elastic material" used here can be a soft material that is elastic (flexible), such as a rubber material or a thermoplastic elastomer.

[0009] In the workpiece assembly device according to the present invention having the above configuration, the workpiece holding function, which was obtained by the cooperation of the holding pins and pin biasing means incorporated inside the cylindrical body (arranged in a row along the radial direction inside the cylindrical body) in the conventional workpiece assembly device described in Patent Document 1, is obtained by a holding ring made of an elastic material that is fitted around the outer periphery of the cylindrical body in an elastically expanded diameter state. Therefore, according to the present invention, the radial thickness of the cylindrical body that constitutes the holding portion can be reduced to make the holding portion more compact, and the number of parts in the holding portion can be reduced to simplify the structure of the holding portion, making it possible to easily and smoothly perform maintenance work (replacement of the holding ring) to restore the workpiece holding ability, etc.

[0010] In the above configuration, it is preferable that the notches (protrusions) are provided at multiple locations spaced apart in the circumferential direction. In this way, the workpiece inserted into the inner circumference of the cylindrical body can be stably held only by the retaining ring made of an elastic material, which effectively reduces the possibility of defects such as scratches being formed on the workpiece when the workpiece is attached to the holding part and when the workpiece held by the holding part is pushed out by the pushing part (when it is assembled to an assembly target). [Effects of the Invention]

[0011] As described above, according to the present invention, it is possible to realize a holding section that is compact and simple in configuration yet is capable of properly holding a workpiece to be assembled to an assembly target, thereby realizing a workpiece assembly device that is highly versatile and has excellent maintenance workability, etc. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic perspective view of a workpiece assembling device according to an embodiment of the present invention, in an initial state, as viewed obliquely from above and in front thereof; [Figure 2] 1 is a schematic perspective view of the workpiece assembly device when the workpiece is attached to the attachment target, as viewed from diagonally above the front. FIG. [Figure 3] 2 is a schematic cross-sectional view of the workpiece assembly device shown in FIG. 1 taken along the AA plane in the same figure. [Figure 4] 1A and 1B are diagrams for explaining the process of mounting a workpiece on a workpiece assembly device, in which (a) is a diagram showing the start of the process, (b) is a cross-sectional view taken along line BB in (a), (c) is a diagram showing an intermediate stage of the process, (d) is a cross-sectional view taken along line BB in (c), (e) is a diagram showing the completion stage of the process, and (f) is a cross-sectional view taken along line BB in (e). [Figure 5] FIG. 10 is a diagram showing the start stage of the workpiece assembling process. [Figure 6] FIG. 10 is a diagram showing an intermediate stage of a workpiece assembling process. [Figure 7] FIG. 10 is a diagram showing the completed stage of the workpiece assembly process. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings (FIGS. 1 to 7).

[0014] The workpiece assembly apparatus 1 of this embodiment shown in FIG. 1 and other figures is installed (suspended) in an assembly line for automobile engines (here, an in-line three-cylinder engine) and is used to assemble a lash adjuster 20 (see FIG. 4(a) and other figures) into a recess 31 provided in a cylinder block 30 (see FIG. 5 and other figures). Therefore, in this embodiment, the lash adjuster 20 and the cylinder block 30 correspond to the "workpiece" and the "object to be assembled," respectively, as defined in the present invention. The lash adjuster 20 is a functional component that constitutes the engine's valve train in cooperation with a camshaft and rocker arm. The lash adjuster 20 includes a cylindrical, bottomed adjuster body 21 housed in the recess 31 of the cylinder block 30, and a hollow plunger 22 disposed on the inner periphery of the adjuster body 21 and displacing in the axial direction of the adjuster body 21.

[0015] The workpiece assembly device 1 includes a linear rail member 2, a first support member 4 fixed to a predetermined position on the rail member 2 (the center portion in the longitudinal direction in the illustrated example), a pair of second support members 5 disposed on either side of the first support member 4 and sliding along the rail member 2, and three workpiece chucks 10 each capable of holding (chucking) a lash adjuster 20, with one workpiece chuck 10 supported by the first support member 4 and one by the pair of second support members 5. Therefore, the workpiece assembly device 1 of this embodiment is capable of assembling three lash adjusters 20 to the cylinder block 30 at one time. Locking components 3 are fixed to both longitudinal ends of the rail member 2 and are engageable with the second support members 5 in the direction of movement. An operating handle 6 for the workpiece assembly device 1 is fixed to each second support member 5.

[0016] The following will provide a detailed description of the work chuck 10 that is provided with the characteristic configuration of the present invention and is included in the work assembly device 1. Since the work chucks 10 supported by the support members 4 and 5 basically have the same structure, the description will be given here by taking the work chuck 10 supported by the second support member 5 as a representative example.

[0017] 3, work chuck 10 includes a holding portion 11 that holds lash adjuster 20, and a push rod 12 that is disposed coaxially with holding portion 11 and is capable of moving up and down relatively to holding portion 11, and that pushes lash adjuster 20 held by holding portion 11 outward (downward) of holding portion 11 (to be assembled into recess 31 of cylinder block 30) as the push rod 12 moves downward relative to holding portion 11. Push rod 12 is fixed to second support member 5 by fastening a nut to a thread formed on one longitudinal end (upper end) of push rod 12, and an accommodation recess 12a is formed on the other longitudinal end (lower end) of push rod 12 in which a portion of lash adjuster 20 (plunger 22) is accommodated.

[0018] The retaining portion 11 comprises a cylindrical body 13 having a cylindrical tube portion 13a into the inner periphery at the bottom end into which (part of) the lash adjuster 20 is inserted, and a flange portion 13b integrally formed with the cylindrical body 13a and projecting radially outward from the upper end of the cylindrical portion 13a, and a retaining ring 14 fitted onto the outer periphery at the bottom end of the cylindrical portion 13a (the outer periphery of the portion into which the lash adjuster 20 is inserted). The retaining ring 14 is formed into an annular shape from an elastic material whose main component is rubber or a thermoplastic elastomer, and is fitted onto the outer periphery of the cylindrical portion 13a in an elastically expanded diameter state. The inner diameter of each portion of the cylindrical portion 13a in the axial direction into which the lash adjuster 20 is inserted is set to be larger by a predetermined amount than the outer diameter of the lash adjuster 20 (the portion of the lash adjuster 20 that is disposed on the inner periphery of the cylindrical portion 13a). Therefore, when lash adjuster 20 is inserted into the inner periphery of the lower end of cylindrical portion 13a of cylindrical body 13, the fit between them is what is known as a loose fit (see JIS B 0401-1).

[0019] The work chuck 10 is attached to the outer periphery of the push rod 12 and further includes a spring member 15 interposed in a compressed state between the support member (second support member 5) and the flange portion 13b of the cylindrical body 13, and a guide shaft 16 having one longitudinal end (upper end) slidably inserted into the second support member 5 and the other longitudinal end (lower end) fixed to the flange portion 13b of the cylindrical body 13. Therefore, in this embodiment, the holding portion 11 forms the movable side of the work chuck 10, and the push rod 12 forms the stationary (fixed) side of the work chuck 10.

[0020] An annular positioning portion 13c for positioning the retaining ring 14 (preventing displacement of the retaining ring 14) is formed in the portion of the cylindrical portion 13a of the cylindrical body 13 where the retaining ring 14 is fitted. As shown in Figures 4(b), 4(d), and 4(f), this positioning portion 13c is formed by arranging two arc-shaped circumferential grooves 13d formed on the outer peripheral surface of the cylindrical portion 13a and two notches 13e that allow a portion (a partial circumferential region) of the retaining ring 14 fitted into the positioning portion 13c to protrude toward the inner circumference of the cylindrical portion 13a of the cylindrical body 13, alternately in the circumferential direction.

[0021] Because the above-described positioning portion 13c is formed on the cylindrical portion 13a of the cylindrical body 13, when the retaining ring 14 is fitted into the positioning portion 13c (fitted in a state in which the diameter is elastically expanded), the retaining ring 14 is deformed into a generally elliptical shape, and protruding portions 14a that protrude radially inward beyond the inner circumferential surface of the cylindrical portion 13a are formed on the retaining ring 14 [see FIG. 4(b)]. The protruding portions 14a are arranged in two opposing locations across the hollow portion of the cylindrical portion 13a, and the distance D between the opposing surfaces of the two protruding portions 14a (the diameter of the inscribed circle that contacts the inner diameter end of each protruding portion 14a) is set to be smaller than the diameter of the portion of the lash adjuster 20 that faces the retaining ring 14 (protruding portions 14a) when the lash adjuster 20 is held by the holder 11. With the above configuration, when lash adjuster 20 is held by retaining portion 11, lash adjuster 20 is held by protruding portion 14a of retaining ring 14 without coming into contact with cylindrical portion 13a of cylindrical body 13 (see FIGS. 4(e) and 4(f)).

[0022] The work of assembling the lash adjuster 20 to the cylinder block 30 using the workpiece assembling device 1 having the above configuration is performed as follows. The work of assembling the lash adjuster 20 is performed by a worker engaged in assembly work on an engine assembly line manually operating the workpiece assembling device 1 while holding the operating handles 6 fixed to each of the pair of second support members 5.

[0023] First, as shown in Fig. 1, the workpiece assembly device 1 is placed in an initial state in which the pair of second support members 5 abuts against the first support member 4. In this initial state, the workpiece chucks 10 supported by the support members 4, 5 are arranged at regular intervals. Next, the workpiece assembly device 1 in the initial state is operated to hold the lash adjusters 20 in the holding portions 11 of the workpiece chucks 10.

[0024] Lash adjuster 20 is held by holding portion 11 in the following manner. First, as shown in Figure 4(a), the holding portion 11 provided on each work chuck 10 is arranged coaxially with the lash adjusters 20 aligned at regular intervals in a parts box in a vertical position (upright position) with the adjuster main body 21 positioned on the bottom, and then the work assembly device 1 is moved downward and the lash adjusters 20 are inserted into the inner periphery of the lower end of the cylindrical portion 13a of the cylindrical body 13. As the downward movement of the work assembly device 1 progresses and the lash adjusters 20 are inserted into the inner periphery of the cylindrical portion 13a, the portion of the retaining ring 14 fitted on the outer periphery (positioning portion 13c) of the cylindrical portion 13a is pushed radially outward, causing the retaining ring 14 to elastically deform [see Figures 4(c) and (d)].

[0025] Then, as shown in Figure 4(e), when the lower end of the push rod 12 abuts against the upper end surface of the adjuster main body 21 and the plunger 22 protruding upward from the adjuster main body 21 is accommodated in the accommodation recess 12a of the push rod 12, the elastic restoring force displaces the protruding portion 14a of the retaining ring 14 radially inward, and the protruding portion 14a abuts against the outer peripheral surface of the lash adjuster 20 (adjuster main body 21), as shown in Figure 4(f). As a result, the lash adjuster 20 is held by the holding portion 11 of each work chuck 10.

[0026] The workpiece assembly device 1, with the lash adjusters 20 held by each holding portion 11 in the above manner, is then moved upward away from the parts box in which the lash adjusters 20 are aligned, and is then positioned above the cylinder block 30 to which the lash adjusters 20 are to be assembled, as shown in Fig. 5. At this time, the second support member 5 is slid along the rail member 2 (see Fig. 2), so that the holding portions 11 of each workpiece chuck 10 are positioned above corresponding recesses 31 provided at predetermined intervals in the cylinder block 30.

[0027] As shown in Figure 5, a spacer 32 is placed on the cylinder block 30, and a guide member 33 is provided on the spacer 32 at a location adjacent to an extension of the center line of the recess 31. The guide member 33 guides the retaining portion 11 (cylindrical body 13) that is inserted into the cylinder block 30 when the lash adjuster 20 is assembled into the recess 31 that is provided in a recessed position in the cylinder block 30. The guide member 33 is provided with a stopper portion 34 that engages with the workpiece assembly device 1 in the insertion direction of the retaining portion 11.

[0028] 5 and 6, while guiding the holding portion 11 (cylindrical body 13) with the guide member 33, the workpiece assembly device 1 is moved downward until the flange portion 13b of the cylindrical body 13 engages with the guide member 33. When the flange portion 13b of the cylindrical body 13 engages with the guide member 33, a portion of the lash adjuster 20 held by the holding portion 11 (the portion protruding below the holding portion 11) is inserted into the recess 31.

[0029] 7, when the workpiece assembly device 1 is further moved downward from the above state until it engages with the stopper portion 34 of the guide member 33, the holding portion 11 (cylindrical body 13) moves upward against the elastic restoring force of the spring member 15, and the push rod 12 moves downward relative to the holding portion 11. When the push rod 12 moves downward relative to the holding portion 11, the lash adjuster 20 engaged with the push rod 12 (the plunger 22 is housed in the housing recess 12a of the push rod 12) also moves downward relative to the holding portion 11. As a result, the protruding portion 14a of the holding ring 14, which has been in contact with the outer peripheral surface of the lash adjuster 20, elastically deforms radially outward, and the state in which the lash adjuster 20 is held by the holding portion 11 is released. Therefore, when the workpiece assembly device 1 is moved upward, the lash adjuster 20 is pushed outward (downward) from the holding portion 11 and assembled into the recess 31 of the cylinder block 30.

[0030] To summarize the characteristic configuration of the workpiece assembly device 1 described above, the holding portion 11 that holds the lash adjuster 20 as the workpiece includes a cylindrical body 13 into whose inner periphery the lash adjuster 20 is inserted (loose fit), and a retaining ring 14 that is formed in an annular shape from an elastic material such as rubber and is fitted onto the outer periphery of the cylindrical body 13 in an elastically expanded diameter state, and the portion of the cylindrical body 13 (cylindrical portion 13a) into which the retaining ring 14 is fitted has a notch 13e that allows the retaining ring 14 to partially protrude into the inner periphery of the cylindrical portion 13a of the cylindrical body 13, and the lash adjuster 20 is held by the protruding portion 14a of the retaining ring 14 that protrudes into the inner periphery of the cylindrical portion 13a.

[0031] That is, in the workpiece assembly device 1 of this embodiment, the workpiece holding function, which was obtained by the cooperation of the holding pins and pin biasing means incorporated inside the cylindrical body (arranged in a row radially inside the cylindrical body) in the conventional workpiece assembly device described in Patent Document 1, is obtained by the retaining ring 14 made of an elastic material that is fitted around the outer periphery of the cylindrical portion 13a of the cylindrical body 13 in an elastically expanded diameter state. Therefore, according to the present invention, the radial thickness of the cylindrical portion 13a of the cylindrical body 13 that constitutes the retaining portion 11 can be reduced to make the retaining portion 11 more compact, and the number of parts of the retaining portion 11 can be reduced to simplify the structure of the retaining portion 11, which makes it possible to easily and smoothly perform maintenance work (replacement of the retaining ring 14) for, for example, restoring the holding ability of the workpiece (lash adjuster 20).

[0032] In particular, in this embodiment, since notches 13e provided in cylindrical body 13 are spaced equally apart in the circumferential direction, protrusions 14a of retaining ring 14 are also spaced equally apart in the circumferential direction. In this manner, lash adjuster 20, which is inserted (loose fit) into the inner periphery of cylindrical portion 13a of cylindrical body 13, can be stably held only by retaining ring 14, which is made of an elastic material, and therefore the possibility of defects such as scratches being formed in lash adjuster 20 when lash adjuster 20 is attached to retaining portion 11, and when lash adjuster 20 held in retaining portion 11 is pushed out by push rod 12.

[0033] As described above, according to the present invention, it is possible to realize a holding portion 11 that is compact and simple in configuration yet is capable of properly holding a lash adjuster 20, and therefore it is possible to realize a work assembly device 1 that is highly versatile and has excellent maintenance workability, etc., at low cost.

[0034] The workpiece assembly device 1 according to one embodiment of the present invention and the method for assembling a workpiece (lash adjuster 20) to an assembly target using the same have been described above, but the embodiments of the present invention are not limited to this.

[0035] For example, the notches 13e formed in the cylindrical body 13 that constitutes the holding portion 11 may be provided in three or more locations in the circumferential direction of the cylindrical body 13. Furthermore, the workpiece assembling apparatus 1 is not limited to being used when assembling the lash adjuster 20 into the recess 31 of the cylinder block 30 that is its assembling object, but can also be used when assembling other workpieces into the assembling object. Furthermore, the workpiece assembling apparatus 1 can also be used by attaching it to automated equipment such as a robot arm. [Explanation of symbols]

[0036] 1 Work assembly device 10 Work chuck 11 Holding part 12 Extrusion rod (extrusion part) 13 Cylinder 13a Cylinder part 13c Positioning part 13d circumferential groove 13e Notch 14 Retaining ring 14a Protrusion 20 Lash adjuster (work) 30 Cylinder block (mounting target) 31 Recess

Claims

1. A workpiece assembling device including a holding unit that holds a workpiece, and a push-out unit that moves coaxially with the holding unit relative to the holding unit to push out the workpiece held by the holding unit and assemble it to an assembly target, the holding portion includes a cylindrical body into whose inner periphery the workpiece is inserted, and a holding ring formed in an annular shape from an elastic material and held on the outer periphery of the cylindrical body in an elastically expanded state; A work assembly device characterized in that a notch is provided in the portion of the cylindrical body into which the retaining ring is fitted to allow the retaining ring to partially protrude into the inner circumference of the cylindrical body, and when the outer surface of the workpiece is held in contact with and held by the protruding portion of the retaining ring that protrudes into the inner circumference of the cylindrical body through the notch, the workpiece is not in contact with the cylindrical body.

2. 2. The workpiece assembly device according to claim 1, wherein the notches are provided at a plurality of locations spaced apart in the circumferential direction.

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