JP2921460B2 - Connecting rod splitting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting rod splitting method used for manufacturing a split split connecting rod, and more particularly to a connecting rod splitting method suitable for mass-producing the connecting rod.

[0002]

2. Description of the Related Art A connecting rod, which is one of the main parts of an automobile engine, is connected to a crankshaft.
The large end has a structure divided into a rod side and a cap side, and each member has conventionally been manufactured in a separate process. However, in light of the recent severe economic situation, the two parts are integrally molded, the large end of the molded product is broken and split into the rod side and the cap side, and the fracture split is combined without machining the fracture split surface The development of mold connecting rods is underway. As the material of the integrated connecting rod product, a sintered product or a sintered forged product that performs forging after sintering in order to ensure breakability is generally used. I have.

[0003] In the manufacture of the split-type connecting rod, it is important to have a technique of manufacturing a conrod integrated molded article in which the large end can be easily divided and a technique of easily dividing the large end.
Regarding the technique of dividing the large end, tension is generally used as described in JP-A-3-14904. In the tension splitting described in the publication, a splitting device that separates and drives a half split type jig inserted into a bearing hole at a large end by a hydraulic cylinder is used. That is, by setting the connecting rod integral molded product in the splitting device, a half-split type split jig is inserted into the bearing hole at the large end, and then the split jig is driven separately, so that the large end is a rod. It is pulled by the side and the cap side, and is divided by breaking.

[0004]

In such a dividing technique, the dividing device becomes expensive, and when performing a large amount of processing, many expensive devices are required. In addition, the work needs to be supplied to many devices in parallel, which complicates the line configuration. Therefore, in mass production of split-type connecting rods,
The division is costly, which is a major problem.
This is because the original purpose of development of the split-type connecting rod is to reduce the manufacturing cost, and if the cost is required for the division in mass production, the original purpose cannot be achieved.

An object of the present invention is to provide an economical and efficient connecting rod splitting method applied to mass production of a split split connecting rod.

[0006]

SUMMARY OF THE INVENTION In the case where the large end portion of the integrally formed connecting rod is divided into pieces by tension, it has been conventionally considered that an impactful tensile force is necessary to obtain a flat fracture surface. Therefore, as described in JP-A-3-14904, a half-split type jig inserted into the large end is momentarily separated and driven by one large-capacity hydraulic cylinder. The present inventors have investigated the relationship between tensile speed and breakability in order to find an economical split energy source that can replace hydraulic cylinders. As a result, the effect of the tensile speed is extremely small, and even in the case of a rolled forged product that is considered to be inferior in rupture properties to a sintered product or a sintered forged product, the same as the impact tensile fracture due to low-speed tension of about 0.05 mm / min. It was found that a flat fracture surface was obtained.

The connecting rod dividing method of the present invention has been developed on the basis of this finding. In the connecting rod dividing method for dividing the large end of the integrally formed connecting rod into a rod and a cap, A split jig is inserted into the bearing hole, and a relative diameter change is generated between the outer diameter of the split jig and the inner diameter of the large end by a material deformation accompanying a temperature change. There is a structural feature in that a tensile force in the dividing direction is added.

[0008] The connecting rod dividing method of the present invention is roughly classified into the following three. That is, there are a case where the outer diameter of the large end is reduced while the dividing jig is inserted into the large end, a case where the outer diameter of the divided jig is increased, and a case where both are used. When the outer diameter of the large end is reduced, the temperature of the large end is reduced. When increasing the outer diameter of the divided jig, there are cases where the temperature of the jig itself is increased and cases where the temperature of another member is changed.

In order to change the temperature of the separate member, a half-split type split jig inserted into the large end portion of the integrally formed connecting rod and divided into two in the split direction is used. (Heating expansion / cooling shrinkage) is transmitted to the dividing jig, and a pair of split pieces constituting the dividing jig perform a separating operation. In that case, only one of the pair of split pieces may be operated, or both may be operated.

The case where the deformation of another member is transmitted to the dividing jig is divided into a case where the deformation of the other member is directly transmitted to the dividing jig and a case where the deformation is transmitted via a direction changing machine or an amplification mechanism. Is done. The direction change is to change the pushing force due to the expansion of another member into a pulling force by a lever or the like.
Amplification is to amplify the amount of deformation of another member using a lever or the like and transmit it to the dividing jig. The levers can serve both as a direction change mechanism and an amplification mechanism.

The heating of the dividing jig and other members is preferably performed by direct current heating or high-frequency induction heating mainly from the viewpoint of efficiency. For cooling the large end portion of the separate member or the connecting rod integrally molded product, forced cooling by a fan and liquid cooling are desirable in terms of efficiency and economy.

In any case, in the connecting rod dividing method of the present invention, heating and cooling are performed at a fixed position while continuously transferring the integrated connecting rod product in series,
Efficient division work can be performed with simple equipment.

The connecting rod-integrated molded product may be any of a sintered product, a sintered forged product, and a rolled forged product, and does not matter the material and the type of manufacturing method.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 1 is a configuration diagram of a line suitable for carrying out the method of the present invention, FIG. 2 is a plan view of a pallet used in the line, FIG. 3 is a side view of the pallet, and FIG. FIG.

In the present method, as shown in FIG. 1, a large number of pallets 1 on which a connecting rod integrated molded product 20 is placed and conveyed are mounted.
0, 10... Are used. Many pallets 10,10 ...
Are arranged at predetermined intervals, move in one direction in the alignment direction at a predetermined speed, and sequentially pass through a heating zone, a material setting position X, a cooling zone, and a material removal position Y on the way. After moving in one direction, it moves in the opposite direction, and passes through the heating zone, the material setting position X, the cooling zone, and the material removing position Y in the middle thereof.

As shown in FIGS. 2 to 4, each pallet 10 has a base plate 11 which is long in a direction perpendicular to the moving direction.
And a round bar-shaped expansion / contraction member 12 horizontally supported on the base plate 11 over substantially the entire length thereof, and a material support table 13 provided on one end of the base 11.

On the material support 13, a connecting rod integrated product 20 is placed with the small end 21 facing one end and the large end 22 facing the other end. On one end of the material support 13, a support pin 14 to which the small end 21 is fitted is protruded, and on the other end, a columnar split jig 15 to which the large end 22 is fitted is protruded. Have been.

The column-shaped dividing jig 15 is a half-split type which is divided into two in the longitudinal direction of the base plate 11, and one of the split pieces 15 a is provided on a fixing portion 13 a of the material support 13.
The other split piece 15b is provided on the movable portion 13b of the material support 13. The movable portion 13b is a slide base that fits into a dovetail groove 13c provided on the upper surface of the other end of the fixed portion 13a, and can move in the longitudinal direction of the base plate 11. Then, in a state where the split pieces 15a and 15b are closely joined, the dividing jig 15
Is a cylindrical body having a circular cross section inserted into the large end portion 22.

The expansion / contraction member 12 is made of a metal having a large linear expansion coefficient.
b. The other end of the expansion / contraction member 12 is connected to a block 16 provided at the other end of the base plate 11. When the expansion and contraction member 12 is at room temperature, the movable portion 13b of the material support 13 is moved to the other end of the material support 13 and separates the split pieces 15a and 15b. When heated, the movable portion 13b moves to one end side of the material support base 13 due to the thermal expansion in the longitudinal direction to unite the split pieces 15a and 15b.

Next, the working procedure of the present method will be described.

In the actual operation, the aligned pallets 10,
Move in one direction in the alignment direction. Thus, the pallet 10 sequentially passes through the heating zone, the material setting position X, the cooling zone, and the material removing position Y. Two parallel electrodes 3 extending in the transport direction of the pallet 10 are provided in the heating zone.
0, 30 are installed. Electrode 3 connected to power supply
Reference numerals 0 and 30 contact both ends of the expansion and contraction member 12 of the pallet 10 moving in the heating zone from above.

When the bullet 10 enters the heating zone,
The electrodes 30, 30 contact both ends of the thermal expansion / contraction member 12. As a result, current flows through the expansion / contraction member 12, and the expansion / contraction member 12 generates heat. By continuing this energization while the expansion and contraction member 12 advances in the heating zone, the expansion and contraction member 12 is heated to a predetermined temperature. Due to this heating, the expansion / contraction member 12 expands in the longitudinal direction, and the split pieces 15a and 15b on the material support table 13 are united. Then, at the material setting position X, the connecting rod integrated molded product 20 is set on the material support table 13, the support pin 14 is inserted into the bearing hole of the small end 21, and the split pieces are combined with the bearing hole of the large end 21. 15a,
15b is inserted.

Here, the connecting rod integrally molded product has been finished, and screw holes for bolting the cap to the rod-side member are formed on both sides of the large end 22. Then, with the bolts 23, 23 loosely screwed into the screw holes on both sides, the conrod-integrated product is set on the material support 13 of the pallet 10.

The pallet 10 on which the connecting rod integral molded product 20 has been set enters a cooling zone, and while passing through this zone, the expansion / contraction member 12 is forcibly cooled by a fan or the like. As a result, the expansion / contraction member 12 contracts in the longitudinal direction, and the movable portion 13b of the material support 13 moves to the other end, so that the split pieces 15a and 15b open. As a result, the large end 22 is pulled and split by the rod side and the cap side. That is, with the contraction of the expansion / contraction member 12, the dividing jig 1 composed of the split pieces 15a and 15b
5 has a large end 22
Is split. The cap separated from the rod side
Since the bolts 23, 23 are mounted in advance, falling off is prevented.

The material after the fracture division of the large end portion 22 is finished
The pallet 10 is removed from the pallet 10 when it reaches the material removal position Y.

When the material is completely removed from the final pallet 10, all the pallets 10, 10,... Are moved in the opposite direction. Also in the backward movement, the breaking division of the large end portion 22 is continuously performed in the same manner as described above.

As described above, in the present method, the break division of the large end portion 22 is continuously and automatically performed only by sequentially setting the connecting rod integral molded products 20 on the moving pallets 10, 10,.... There is no need to provide a drive source for the dividing jig 15 on each pallet 10, and the expansion and contraction members 1
Since a device for heating and cooling 2 may be installed, the equipment is extremely simple.

The condition for breaking and dividing the large end portion 22 of the connecting rod integral molded product 20 is represented by the diameter expansion ratio of the large end portion 22 in the rod longitudinal direction. This diameter expansion rate is determined by the mechanical properties of the material constituting the connecting rod-integrated product 20, particularly the elongation. Therefore, in this method, it is necessary to set the diameter expansion ratio of the split jig 15 in the rod longitudinal direction so that the large end portion 22 expands in the rod longitudinal direction beyond the limit diameter expansion ratio determined by the material.

The connecting rod integral molded product is 0.3C-0.7Si
-1.2Mn-0.07P-0.05S-0.2Cr-0.2V-
In the case of a rolled forged product having a steel composition of 0.15 Pb and an inner diameter at the large end of 50 mm, the elongation of the steel is 4 mm in the parallel portion of the test piece, 22 mm in the parallel portion length, 20 mm in GL, and the tensile speed of the test piece ( Since the strain rate is 5% under the test condition of 1.5 × 10 ^-2 / S, in order to split the large end by breaking, the inner diameter of the large end should be 5% or more, and the absolute value should be 2.5 mm or more. Need to increase.

Therefore, an outer diameter of 50 mm is used as the expansion / contraction member.
Using an S45C round bar having a length of 3 m, the distance between the electrodes was set to 2 m, and this range was directly heated by heating to 300 ° C. After setting the material, the material was cooled by air to shrink the expansion / contraction member. Since the linear expansion coefficient of S45C is 11.7 × 10 ⁻⁶ / deg, the expansion / contraction member expands in the longitudinal direction by about 7 mm by heating, and then contracts by about 7 mm by cooling. Part of the shrinkage is absorbed by the rattling of the device, etc., but when the shrinkage exceeds the limit expansion ratio at the large end, the split jig expands, causing the large end to break into the rod side and the cap side. Was done. The outer diameter of the split jig was 49 mm in a united state.

The inner diameter of the large end when the two members after the division were fastened was measured in the rod longitudinal direction and the rod width direction, and the accuracy of the inner diameter after the division was evaluated by (longitudinal diameter-width direction diameter). The result was 0.05 to 0.10 mm. Here, the integrally formed connecting rod is a rolled and forged product which is considered to be inferior in breakability to a sintered product and a sintered forged product. The tensile speed is estimated to be about 2.3 × 10 ⁻³ / S in terms of strain rate. Nevertheless, the fracture split surfaces showed practically sufficient flatness.

By changing the heating temperature and heating range of the expansion / contraction member, or by changing the material to stainless steel having a large linear expansion coefficient, the diameter expansion ratio of the split jig can be arbitrarily adjusted.

In the above example, the diameter of the dividing jig 15 is increased by the cooling and shrinking deformation of the expanding and contracting member 12, and the split piece 15b of the dividing jig 15 on the side close to the expanding and contracting member 12 is fixed, and the expanding and contracting member 12 is fixed. If the expansion / contraction member 12 is connected to the movable split piece 15a that is separated from the expansion jig 15, the split jig 15 can be expanded by the thermal expansion / deformation of the expansion / contraction member 12. Also, when the expansion / contraction member 12 is connected to the movable split piece 15b via a lever, the diameter of the split jig 15 can be increased when the expansion / contraction member 12 expands. Since the amount of deformation of the member 12 can be amplified and transmitted to the split piece 15b, the expansion and contraction member 12 can be downsized.

In the above example, the deformation of the expansion / contraction member is transmitted to a half-split type split jig to change the diameter of the split jig. As shown in FIG. 5, an integrated split jig 15 is used. The large end 22 may be pulled toward the rod side and the cap side by the thermal expansion of the jig itself. Integrated split jig 1
5 is shaped so that both sides are removed so that the expanding deformation generates an effective tensile force in the longitudinal direction of the rod.
Also, using the same integrated jig 15, the large end 22 is reduced in diameter by cooling after heating the large end 22, so that a tensile force in the rod longitudinal direction is applied to the large end 22. You may.

In any case, the connecting rod integral molded product 2
0, a relative diameter change is generated between the outer diameter of the split jig 15 inserted into the large end part 22 and the inner diameter of the large end part 22 by material deformation due to temperature change. Since a tensile force is applied, the large end 22 can be divided by a single heating / cooling device provided at a fixed position while the molded product 20 is conveyed in series.

[0036]

As described above, according to the connecting rod dividing method of the present invention, since the large end portion is tensile-divided due to material deformation due to temperature change, a driving source corresponding to the dividing jig is not required, and a large amount of processing is performed. The processing can be economically performed with simple equipment. Therefore, it is very effective in reducing the manufacturing cost in mass production of the split-type connecting rod.

[Brief description of the drawings]

FIG. 1 is a block diagram of a line suitable for carrying out the method of the present invention.

FIG. 2 is a plan view of a pallet used in the same line.

FIG. 3 is a side view of the pallet.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a plan view showing another apparatus configuration suitable for carrying out the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pallet 12 Expansion / contraction member 15 Split jig 15a, 15b Split piece 20 Connecting rod integral molded product 22 Large end part 30 Electrode

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B26F 3/06 B23P 13/00 F16C 7/02

Claims (1)

(57) [Claims] In a connecting rod dividing method for dividing a large end portion of an integrally formed connecting rod into a rod side and a cap side, a dividing jig is inserted into a bearing hole of the large end portion, and an outer diameter of the dividing jig is determined. A connecting rod dividing method, wherein a relative diameter change is generated between the inside diameter of the large end and a material deformation due to a temperature change to apply a tensile force in a dividing direction to the large end.