JP2008018488A - Cracking groove machining method and apparatus for connecting rod - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machining method and apparatus for surely forming a pair of cracking grooves at a low cost in the inner peripheral surface of a large end hole of a connecting rod. <P>SOLUTION: The apparatus includes: a first fixed tool and a second fixed tool fixed to a placing table 14 and engaged with the large end hole 18 of the connecting rod 12; a pair of pressing members 34a, 34b, which displace in the opposite directions to be spaced from each other, and project the blade parts through slits radially outward by a predetermined length to press the inner peripheral surface of the large end hole 18, thereby forming a pair of cracking grooves; a wedge member 22 pressed in between the paired pressing members; and a load mechanism for applying impact load to the wedge member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  For example, the present invention provides a method for breaking and separating a connecting rod into a cap portion and a rod portion on an inner peripheral surface of a large end hole of the connecting rod after a connecting rod constituting a vehicle engine is integrally formed. The present invention relates to a method and apparatus for processing a cracking groove for a connecting rod that forms a cracking groove.

  Conventionally, a crankshaft of a vehicle engine and a piston are connected via a connecting rod (hereinafter simply referred to as a connecting rod), and the vertical movement of the piston is converted into a rotational movement of the crankshaft.

  This connecting rod has a bearing mounted on the inner surface of a large end hole formed at the large end portion on one end side thereof, supports the journal of the crankshaft, and is formed at the small end portion on the other end side. A piston pin that is inserted into the piston through a separate bearing is inserted into the small end hole.

  In general, the connecting rod is formed by forging, a method of separately manufacturing a shaft portion and a cap portion, each of which is a connecting rod body, and a shaft portion and the cap after the connecting rod is integrally manufactured. There is known a method for manufacturing cracking of a connecting rod that is separated into parts.

  For example, when separating the integrally manufactured connecting rod into the shaft portion and the cap portion, first, at the position that becomes the boundary between the shaft portion and the cap portion on the inner surface of the large end hole formed in the large end portion. The pair of breakage promoting grooves are formed to face each other. This groove is formed at a predetermined depth by broaching or laser processing with a cutting tool for processing at or after the connecting rod forming step.

  In such a processing apparatus, a broach blade is formed along the axial direction on the outer peripheral surface of the jig, the jig is inserted into the large end hole of the connecting rod, and the broach blade is applied to the inner peripheral surface of the large end hole. Displace while touching. Thereby, the broach groove | channel is formed in the internal peripheral surface of a large end hole along an axial direction (for example, refer patent document 1).

Japanese Patent No. 3012510

  By the way, in the case of performing broaching on the large end hole of the connecting rod by the connecting rod processing method disclosed in Patent Document 1, in order to break and separate the shaft portion and the cap portion equally and smoothly, the large end The position and depth of the groove for promoting breakage formed on the inner surface of the hole are substantially equal, in other words, the pair of grooves formed in the large end hole are formed in a symmetrical shape. Is required.

  When the groove for promoting breakage is formed by broaching, the broaching blade of the jig used for broaching has a substantially U-shaped cross section, so the groove shape formed by the jig Becomes substantially U-shaped. However, with the broaching blade of the jig, it is difficult to form a break-promoting groove into a substantially sharper, substantially v-shape, so that the connecting rod is connected to the shaft portion and the cap portion by the break-promoting groove. It is necessary to increase the impact load at the time of separation, and it is difficult to break and separate the connecting rod reliably and evenly.

  Further, in the tip processing method using a throw-away tip or the like, since the inner peripheral surface of the large end hole of the connecting rod is intermittently cut by a plurality of tips, the tops of the cutting blades of the plurality of tips wear, In grooving, it is difficult to process the groove angle at an acute angle, and there is a problem that stress concentration during cracking is low.

  Further, when a groove for promoting breakage is formed by laser processing, a hardened layer is formed in the vicinity of the groove on the inner peripheral surface of the large end hole. There is a concern that the strength may be affected, and there is a problem that dust such as sludge generated when the groove is formed adheres to the inner peripheral surface of the large end hole.

  The present invention has been made in consideration of the above-described various problems and the like, and is capable of reliably forming a pair of cracking grooves on the inner peripheral surface of the large end hole of the connecting rod at a low cost. An object of the present invention is to provide a method and apparatus for processing a cracking groove for a rod.

In order to achieve the above object, the present invention has a large end and a small end, in order to break and separate the integrally formed connecting rod into a cap portion and a rod portion. In a processing apparatus for a cracking groove for a connecting rod that forms a pair of cracking grooves at opposite positions of an inner peripheral surface in an end hole,
A fixing jig that engages with a large end hole of the connecting rod and fixes the large end,
Disposed in the large end hole so as to face each other and displaced in opposite directions away from each other, the blade portion protrudes from the slit formed in the fixing jig by a predetermined length in the radially outward direction. A pair of pressing members;
A wedge member that can be press-fitted between the pair of pressing members;
A load mechanism for applying an impact load to the wedge member;
It is characterized by providing.

  In this case, the protrusion amount of the blade portion of the pair of pressing members may be set by a clearance formed between the inner wall of the fixing jig and the outer wall of the pressing member.

  According to the present invention, first, the connecting rod is fixed by setting the large end hole of the connecting rod to the fixing jig. Subsequently, an impact load is applied to the wedge member via a load mechanism, and the wedge member is press-fitted between the pair of pressing members.

  In this case, when the wedge member is press-fitted, the pair of pressing members are displaced in the opposite directions away from each other, and the blade portions formed on the pair of pressing members enter the slits of the fixing jig. By projecting a predetermined length from the slit in the radially outward direction, the inner peripheral surface of the large end hole is pressed to form a pair of cracking grooves.

  As described above, in the present invention, the pair of cracking grooves is surely provided in a simple direction by applying an impact load to the wedge member and displacing the pair of pressing members in a direction away from each other to form the pair of cracking grooves. Can be formed.

  According to the present invention, the following effects can be obtained.

  That is, an impact load is applied to the wedge member to displace the pair of pressing members in a direction away from each other, and the blade portions of the pair of pressing members press the inner peripheral surface of the large end hole, thereby connecting A pair of cracking grooves can be reliably and inexpensively formed on the inner peripheral surface of the large end hole of the rod.

  A method for processing a cracking groove for a connecting rod according to the present invention will be described in detail below with reference to the accompanying drawings by giving a preferred embodiment in connection with a processing apparatus for performing the method.

  In FIG. 1, reference numeral 10 indicates a processing apparatus for performing a method of processing a cracking groove for a connecting rod according to an embodiment of the present invention.

  The processing apparatus 10 includes a fixing mechanism 16 that positions and fixes a connecting rod 12 (hereinafter simply referred to as a connecting rod 12) to the upper surface of the mounting table 14, and a first fixing jig that engages with a large end hole 18 of the connecting rod 12. A groove processing portion 24 including a wedge member 22 that is press-fitted in order to expand 20a and the second fixing jig 20b in a direction away from each other; and a lower portion of the mounting table 14; On the other hand, a load mechanism 26 (see FIGS. 7 and 8) is provided that applies an impact load in the vertical downward direction and displaces the wedge member 22 in the vertical direction.

  As shown in FIGS. 2 and 3, the groove processing portion 24 has an outer peripheral shape that substantially corresponds to the inner diameter of the large end hole 18 of the connecting rod 12, and is fixed to the upper surface of the mounting table 14. The first fixing jig 20a and the second fixing jig 20b that hold the large end hole 18, and the through hole formed between the first fixing jig 20a and the second fixing jig 20b and the mounting table 14 are formed. A wedge member 22 provided with a pair of tapered surfaces 28 which are provided so as to be displaceable along the through-holes and which are gradually reduced in width toward the lower side on both side surfaces substantially orthogonal to the axis of the connecting rod 12; A pair of pressing members 34a and 34b that simultaneously form a pair of cracking grooves 32 (see FIG. 10A) by pressing the inner peripheral surfaces of the large end hole 18 opposite to each other with a blade portion 30 having an acute cross section. To. In this case, the inclination angles of the pair of tapered surfaces 28 formed on both side surfaces of the wedge member 22 are set to be the same.

  A pair of narrow slits 36 facing each other is formed between the first fixing jig 20a and the second fixing jig 20b in a direction substantially orthogonal to the axis of the connecting rod 12 (see FIG. 3). ), And the cutting edge 30 of the pressing member 34a, 34b is provided so as to be able to enter the slit 36 and protrude from the slit 36 by a predetermined length along the radially outward direction. In this case, the protrusion amount T (see FIG. 4) of the blade portion 30 protruding from the slit 36 corresponds to the groove depth of the cracking groove 32 having a v-shaped cross section.

  Further, a substantially v-shaped clearance 38 is formed between the inner walls of the first fixing jig 20a and the second fixing jig 20b and the outer walls of the pair of pressing members 34a, 34b (see FIG. 2). By appropriately adjusting the clearance 38, the protruding amount of the blade portion 30 protruding from the slit 36 is determined, and consequently the groove depth of the cracking groove 32 is set.

  The pair of pressing members 34 a and 34 b are formed, for example, from a super hard material in a substantially equilateral triangular shape in cross section, and a blade portion 30 having an acute angle cross section is provided at the apex adjacent to the large end hole 18. Further, a guide surface 40 is formed on the side surface opposite to the blade portion 30 so as to be in sliding contact with the tapered surface 28 of the wedge member 22 and to gradually reduce the width toward the lower side. The inclination angles of the guide surfaces 40 respectively formed on the pair of pressing members 34a and 34b are set to be the same.

  The inner wall surfaces of the first fixing jig 20a and the second fixing jig 20b facing the taper surface 28 of the wedge member 22 are not inclined surfaces but are formed as vertical surfaces. A predetermined gap 41 is formed between the taper surface 28 and the vertical surfaces of the first fixing jig 20a and the second fixing jig 20b so that the wedge member 22 can be displaced along the vertical direction. .

  The fixing mechanism 16 includes a first fixing member 42a that fixes a substantially central portion of the connecting rod 12 and a second fixing member 44b that fixes the large end portion 46 of the connecting rod 12 by a bolt 44a that applies a pressing force.

  As shown in FIG. 10A, the connecting rod 12 is composed of a large end portion 46 formed wide on one end side and a small end portion 48 formed narrow on the other end side. A large end hole 18 through which a journal of a crankshaft (not shown) is inserted is formed in 46.

  The load mechanism 26 includes a preliminary load applying mechanism 50, and the preliminary load applying mechanism 50 is provided with a first hydraulic cylinder 56 that generates a preliminary load applied to the wedge member 22. The first hydraulic cylinder 56 includes a piston rod 62 connected to the end of the wedge member 22 via a connecting mechanism 60 including a connecting pin 58 and the like, and an annular step surface 62a formed on the piston rod 62. A piston 64 having a stepped portion 64a to be engaged is provided.

  The piston rod 62 penetrates the central part of the piston 64 and is slidable with respect to the piston 64. Accordingly, the piston 64 of the first hydraulic cylinder 56 is integrally displaced with respect to the piston rod 62 in the press-fitting direction of the wedge member 22 and can be separated in the direction opposite to the press-fitting direction of the wedge member 22. ing. In other words, the first hydraulic cylinder 56 can apply the preliminary load only in one direction (vertically downward) of the piston rod 62 via the piston 64.

  The first hydraulic cylinder 56 and the load mechanism 26 are provided with a common load transmission shaft 66 connected to the wedge member 22 via a piston rod 62. The shaft 66 is formed integrally with the piston rod 62 on the step surface 62a side. A flange portion 66 a is provided on the other end side of the shaft 66, and the position of the flange portion 66 a can be adjusted in the axial direction of the shaft 66.

  On the load mechanism 26, a weight 57 is placed, and a lift table 68 for generating an impact load applied to the wedge member 22 through the shaft 66 by contacting the flange portion 66a from above, and the lift A set of guide members 70a and 70b that slidably support the table 68 along the vertical vertical direction, and a set of buffer members 72a and 72b that alleviate the impact of the falling lift table 68 are provided. .

  The load mechanism 26 includes a stopper mechanism (not shown) that can adjust the lower limit position of the drop stroke of the lift table 68, and a lift table return mechanism (not shown) that returns the dropped lift table 68 to the upper drop standby position. And a returning cylinder (not shown) for returning the wedge member 22 displaced toward the lower side to the initial position.

  The processing apparatus 10 that performs the method of processing a cracking groove for a connecting rod according to an embodiment of the present invention is basically configured as described above. Next, its operation and effects will be described.

  First, as shown in FIG. 1, the connecting rod 12 in which the cracking groove 32 is formed is fixed to the upper surface of the mounting table 14 via the first fixing member 42a and the second fixing member 42b.

  Subsequently, by driving the first hydraulic cylinder 56 of the preliminary load applying mechanism 50, the piston 64 is urged downward, and is engaged with the stepped portion 64a as the piston 64 descends. The piston rod 62 is similarly actuated downward via the step surface 62a (see FIG. 7). At the same time, the wedge member 22 connected to the piston rod 62 is biased downward, and a preliminary load is applied to the wedge member 22.

  In this case, the preliminary load applied to the wedge member 22 is set such that the blade portion 30 of the pair of pressing members 34 a and 34 b enters the slit 36 and the blade portion 30 does not protrude from the slit 36. .

  Thus, in a state where the preload is applied to the large end hole 18 of the large end portion 46 of the connecting rod 12, the lift table 68 is moved together with the weight 57 to the guide member 70a after the stopper for the lift table 68 is released. , 70b (see FIG. 8). Therefore, when the dropped lift table 68 contacts the flange portion 66a of the shaft 66, the shaft 66 is urged downward and an impact load is applied to the wedge member 22 in the vertically downward direction. .

  By applying a predetermined impact load to the wedge member 22, the wedge member 22 is press-fitted between the pair of pressing members 34a and 34b, and the tapered surface 28 of the wedge member 22 and the pair of pressing members 34a, Under the sliding action of the guide surface 40 of 34b, the pair of pressing members 34a, 34b slides in the horizontal direction and in the opposite directions apart from each other (see FIG. 6).

  When the pair of pressing members 34a and 34b slide in a direction away from each other, the blade portion 30 of the pressing members 34a and 34b enters the slit 36, and from the slit 36 toward the radially outward direction. It protrudes by a length (see FIG. 4). At that time, a pair of cracking grooves 32 having a substantially uniform depth are formed on the inner peripheral surfaces of the large end hole 18 of the connecting rod 12 facing each other by the blade portions 30 of the pressing members 34 a and 34 b protruding from the slit 36. Formed simultaneously. The pair of cracking grooves 32 are formed to face each other in a direction substantially orthogonal to the axis of the connecting rod 12, and the groove shape is formed in a substantially v-shaped cross section by the blade portions 30 of the pressing members 34a and 34b.

  After the cracking groove 32 is formed, the wedge member 22 is raised and returned to the initial position via a return cylinder (not shown), and a pair of pressing members 34a and 34b approach each other under the action of a return mechanism (not shown). Then, the blade part 30 returns to the initial position separated from the slit 36.

  As a result, a pair of cracking grooves 32 opposed to each other on the inner peripheral surface of the large end hole 18 of the connecting rod 12 fixed to the upper surface of the mounting table are approximately in position and depth with respect to the axis of the connecting rod 12. It is formed in a uniform symmetrical shape.

  As described above, in the present embodiment, a predetermined impact load is applied to the wedge member 22 by the load mechanism 26 and the wedge member 22 is lowered to separate the pair of pressing members 34a and 34b from each other. When the blades 30 of the pressing members 34a and 34b are simultaneously displaced in the radially outward direction and press the inner peripheral surface of the large end hole 18, an optimal breakage promotion consisting of a linearly extending groove is provided. A pair of cracking grooves 32 having a v-shaped cross section can be press-molded. The pair of cracked grooves 32 that have been press-molded are each work hardened.

  For this reason, in a subsequent process, for example, a fracture separating jig or the like (not shown) is inserted into the large end hole 18 of the connecting rod 12 in which a pair of cracking grooves 32 are formed, and a radius is formed on the inner peripheral surface of the large end hole 18. By pressing outwardly, the connecting rod 12 can be reliably controlled with the pair of cracking grooves 32 as starting points of breakage, and the rod portion 74a and the cap portion 74b can be reliably and accurately broken. Can be separated (see FIG. 10B). At that time, the connecting rod 12 can be reliably and accurately separated from the cracking groove 32 by the fracture separating jig with a smaller pressure than in the past.

  Furthermore, compared with the case where a groove is formed in the large end hole 18 by conventional broaching or laser processing, the equipment cost can be reduced.

  According to the present embodiment, by forming the cracking groove 32 for promoting the optimal breakage, it is possible to reduce the breaking load when splitting into the cap part 74b and the rod part 74a, and the optimum part. From the above, it is possible to perform a fracture having an optimum fracture surface. Therefore, the temporary recombination of the cap part 74b and the rod part 74a, which are broken and divided in the subsequent process, can be reliably performed.

  Further, in the present embodiment, the cracking groove 32 can be formed by inexpensive processing equipment, and the groove shape can be processed at substantially the same level as laser processing. As a result, in the present embodiment, it is possible to accurately control the groove shape of the cracking groove 32, and it is possible to easily obtain the optimum groove shape for promoting fracture.

  Furthermore, in the present embodiment, the cracking groove 32 is described as being press-molded with respect to the large end hole 18 of the connecting rod 12 based on the impact load due to the fall of heavy objects, but the present invention is not limited to this. For example, as shown in the processing apparatus 10a according to another embodiment of FIG. 9, the wedge member 22 is pulled downward by only the driving force of the hydraulic cylinder 80 functioning as a single actuator. An impact load may be applied to the wedge member 22.

It is a partially-omission perspective view of the processing apparatus which implements the processing method of the cracking groove for connecting rods concerning an embodiment of the invention. It is a partial top view of the processing apparatus shown in FIG. It is a partially broken perspective view which shows the groove processing part which comprises the processing apparatus of FIG. It is a partially omitted enlarged plan view showing a state where the blade portion of the pressing member slides and the inner peripheral surface of the large end hole of the connecting rod is pressed. It is a longitudinal cross-sectional view which shows the state before an impact load is provided with respect to a wedge member by a load mechanism. It is a longitudinal cross-sectional view which shows the state to which the impact load was provided with respect to the wedge member by the load mechanism, and a pair of press member slid to the mutually opposite direction. It is a longitudinal cross-section structure figure of the load mechanism which comprises the processing apparatus of FIG. FIG. 8 is a longitudinal sectional structural view showing a state in which the lifting table has dropped from the state shown in FIG. 7 and an impact load is applied to the wedge member. It is a longitudinal cross-sectional structure figure of the processing apparatus which concerns on other embodiment of this invention. FIG. 10A shows a state in which a pair of cracking grooves are formed in mutually opposing portions of the inner peripheral surface of the large end hole of the large end portion of the connecting rod, and FIG. 10B shows that the large end portion is a cap portion and a rod. It is a perspective view which shows the state fractured | rupture-divided into the part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a ... Processing apparatus 12 ... Connecting rod 14 ... Mounting stand 16 ... Fixing mechanism 18 ... Large end hole 20a, 20b ... Fixing jig 22 ... Wedge member 24 ... Groove processing part 26 ... Load mechanism 28 ... Tapered surface 30 ... Blade Portion 32 ... Cracking grooves 34a, 34b ... Pressing member 36 ... Slit 38 ... Clearance 40 ... Guide surface 50 ... Preloading mechanism 56, 80 ... Hydraulic cylinder 57 ... Weight 66 ... Shaft 68 ... Lifting table

Claims (3)

A pair of connecting rods having a large end portion and a small end portion, which are integrally molded, are arranged at positions opposed to the inner peripheral surface of the large end hole of the large end portion in order to break and separate the cap rod and the rod portion. In the processing device of the cracking groove for the connecting rod that forms the cracking groove,
A fixing jig that engages with a large end hole of the connecting rod and fixes the large end,
Disposed in the large end hole so as to face each other and displaced in opposite directions away from each other, the blade portion protrudes from the slit formed in the fixing jig by a predetermined length in the radially outward direction. A pair of pressing members;
A wedge member that can be press-fitted between the pair of pressing members;
A load mechanism for applying an impact load to the wedge member;
An apparatus for processing a cracking groove for a connecting rod, comprising: The apparatus of claim 1.
An apparatus for processing a cracking groove for a connecting rod, wherein the protruding amount of the blade portions of the pair of pressing members is set by a clearance formed between the inner wall of the fixing jig and the outer wall of the pressing member. A pair of connecting rods having a large end portion and a small end portion, which are integrally molded, are arranged at positions opposed to the inner peripheral surface of the large end hole of the large end portion in order to break and separate the cap rod and the rod portion. In a method of processing a cracking groove for a connecting rod that forms a cracking groove,
Fixing the connecting rod by setting a large end hole of the connecting rod in a fixing jig;
Applying an impact load to the wedge member and press-fitting between the pair of pressing members;
The pair of pressing members are displaced in the opposite directions away from each other by the wedge member, and the inner peripheral surface of the large end hole is pressed by a blade portion formed on the pair of pressing members to form a pair of cracking grooves. And a process of
A method of processing a cracking groove for a connecting rod, comprising:

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