JP2000304028A - Manufacturing method of connecting rod and connecting rod - Google Patents

Abstract

(57) [Summary] [Problem] To reduce the weight of a connecting rod by eliminating the need for a conventional weight adjustment boss, and eliminate the need for a large-scale numerically controlled machine tool.
The step of loosening and tightening the bolt is omitted. A connecting rod (23) is provided without providing a weight adjusting boss.
The weight is adjusted by removing a desired number of the boring reference seat members 35 and 37 for clamping (for pressing during boring). Individual boring reference seat member 3
The need for a numerically controlled machine tool for finely adjusting the shaving amount of 5, 37 is eliminated. Individual boring reference seat members 35, 3
Since the volume and cross-sectional area of 7 are small and the stress at the time of shaving is smaller than that of the conventional single weight adjusting boss, a loosening step for releasing the stress is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting rod manufacturing method and a connecting rod for an internal combustion engine of an automobile or the like, and more particularly to a connecting rod manufacturing method and a connecting rod capable of easily adjusting the weight.

[0002]

2. Description of the Related Art A connecting rod in an internal combustion engine needs to be adjusted in weight for the purpose of reducing vibration during high-speed movement, and particularly in a V-type engine, very strict adjustment is required due to its vibration characteristics. Conventionally, as shown in FIG. 5, the cap 2 of the connecting rod 3 is provided with a cylindrical or rectangular parallelepiped weight adjusting boss 4 having a diameter of about 8 mm.
First, the weight of the connecting rod 3 obtained by forging is measured,
Next, the weight of the connecting rod 3 is adjusted to the target value by performing a so-called balance cutting step of precisely shaving the weight adjusting boss 4 by a numerically controlled machine tool by a length corresponding to a difference from a predetermined target value. It is configured.

In the conventional connecting rod manufacturing method of performing the balance cutting step, as shown in FIG. 6, first, rough boring is performed on the large end hole 12 (S101), and then the balance cutting step is performed (S102). Since a large stress is generated in the entire connecting rod 3 in the balance cutting step, the bolts 5 and the nuts 6 that fasten the rod 1 of the connecting rod 3 and the cap 2 are loosened and tightened to release this stress. Perform the loosening and tightening process (S
103), after performing finish boring and finish honing without stress (S104, S105) to eliminate the step of the mating surface 11, washing (S106) and measuring the weight / inner diameter (S107) to manufacture End the process. Each of the steps S101 to S107 is performed by one individual processing machine in each step.

In the series of manufacturing steps, in the balance cutting step of step S102, as shown in FIG. 7, first, the diameter of the large end hole 12 is measured in order to estimate the allowance (1 to 2 g) of the finished boring. (S102-1) Then, the height of the end face of the weight adjusting boss 4 is measured in order to consider the dimensional variation of the individual connecting rods 3 (S102-2), and then the weight of the connecting rod 3 is measured. The machining amount is calculated based on the difference between the measured weight value and the predetermined target value and the amount of finish boring that has been predicted previously (S10).
2-3), the weight adjustment boss 4 is cut by a necessary cutting depth based on the calculated machining amount (S102-).
4).

[0005]

However, the weight adjusting boss 4 is absolutely unnecessary except for adjusting the weight, and such a member should not be provided in consideration of reducing the weight of the entire engine. Is desirable.

On the other hand, in the above-described balance cutting process, the amount of shaving of the weight adjusting boss 4 is slightly different depending on the individual connecting rods 3, so that an expensive and large-scale numerically controlled machine tool must be used for the shaving. Furthermore, since a large stress is generated when the weight adjusting boss 4 is scraped, a dedicated device for performing the loosening and tightening step (S103) for releasing the stress is required.

The present invention has been made in view of the above problems, and has as its object to reduce the weight of a connecting rod by eliminating the need for a conventional weight adjusting boss, and to eliminate the need for a large-scale numerically controlled machine tool. An object of the present invention is to provide a means for simplifying the production by omitting the loosening step.

[0008]

According to a first aspect of the present invention, there is provided a weight measuring step for measuring the weight of a connecting rod before weight adjustment, and a method for measuring the weight of the connecting rod based on the measured value obtained in the weight measuring step and a predetermined target value. A reference seat member removing step of removing a desired number of a plurality of boring reference seat members provided near the large end hole of the connecting rod large end and used for clamping when boring the large end hole. A method for manufacturing a connecting rod, comprising:

In the first aspect of the present invention, the connecting rod is provided near the large end hole at the large end of the connecting rod and is used for clamping when boring the large end hole, and is necessary in the manufacturing process but not particularly in the product. From the plurality of boring reference seat members,
The weight is adjusted by removing the desired number. Therefore, it is not necessary to provide a weight adjusting boss as in the related art, and it is possible to reduce the weight of the connecting rod and thus the entire engine.

The amount of adjustment of the weight is increased or decreased by changing the number of boring reference seat members to be shaved, so that it is not necessary to finely adjust the shaving amount of each boring reference seat member. Therefore, there is no need to use expensive and large-scale numerically controlled machine tools for this shaving.
For example, a simple processing device such as pushing out a boring reference seat member with a hydraulically driven cutting tool is sufficient. In addition, since a plurality of boring reference seat members are provided, the volume and cross-sectional area of each boring reference seat can be small, and the stress generated when cutting the same is less than that of a conventional weight adjusting boss. Therefore, the loosening step of releasing the stress as in the related art is not required, and the manufacturing process can be greatly simplified.

According to a second aspect of the present invention, a plurality of boring reference seat members used for clamping when boring the large end hole are provided near the large end hole at the large end of the connecting rod. The reference seat member for use is a connecting rod characterized by constituting a predetermined weight unit to be used for adjusting the weight of the connecting rod by removing a desired number of the plurality of boring reference seat members. .

According to the second aspect of the present invention, a desired number of boring reference seat members constituting a predetermined weight unit to be used for adjusting the weight of the connecting rod are removed to adjust the weight of the connecting rod. Therefore, the same effect as the first aspect of the present invention can be obtained.

According to a third aspect of the present invention, in the connecting rod according to the second aspect of the present invention, at least a part of the plurality of boring reference seat members is heavy, and at least one of the plurality of boring reference seat members is heavy. The boring reference seat member of the portion is a connecting rod characterized by a small weight.

In the third aspect of the present invention, a part of the boring reference seat member having a large weight and another part of the boring reference seat member having a small weight are provided. By shaving in combination, fine weight adjustment can be performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described in detail with reference to the drawings. In FIG. 1, a connecting rod 23 according to the embodiment of the present invention includes a rod 25 and a cap 22 connected to bolts 25.
The rod 21 has a small end 27 at the upper end in the figure, and the rod 21 and the cap 22 at the lower end in the figure.
Is formed. The small end 27 has a small end hole 26 for inserting a piston pin (not shown).
However, a large end hole 32 is formed in the large end portion 29 for inserting a crankpin (not shown). A characteristic feature of the connecting rod 23 of the present embodiment is that the weight adjusting boss 4 in the conventional connecting rod 3 does not exist.

A flat surface 33, which is smoothed by cutting, is formed on each of the front surface and the back surface around the large end hole 32, and two large portions of the flat surface 33 on the cap 22 side are formed. Boring reference seat member 35 used for clamping (for holding) when boring the end hole 32.
However, a boring reference seat member 37 is formed at each of two places on the rod 21 side of the flat surface 33.
These boring reference seat members 35 and 37 are used for adjusting the weight of the connecting rod 23 by removing a desired number in a balance cutting step described later. The weight of the boring reference seat member 35 is about 1 g and the rod 21
The weight of the side boring reference seat member 37 is about 0.5 g.

A process for manufacturing such a connecting rod 21 will be described below. As shown in the flowchart of FIG. 2, first, rough boring is performed on the large end hole 32 (S201), and then finishing boring and finishing honing are performed (S201).
202, S203) to perform the operation of eliminating the step on the mating surface 31. In each of the rough boring (S201), the finishing boring (S202), and the finishing honing (S203), the boring reference seat members 35 and 37 are used for clamping (pressing) the connecting rod 23.
Next, balance cut and weight / inner diameter measurement are performed (S2
04) Then, the manufacturing process is completed by performing washing (S205). These steps S201 to S205
Are performed by one individual processing machine for each process.

In this series of manufacturing steps, the balance cutting and weight / inner diameter measuring steps in S204 are performed according to the procedure shown in FIG. That is, first, the weight of the connecting rod 23 is measured, and based on the difference between the measured weight value and the optimum value as the target value, the boring reference seat member 3 is used.
Which and which of 5 and 37 are to be removed, that is, the processing location is determined (S204-1). This determination is made in S204
The following processing is performed in a calculation unit built in a processing machine that performs the balance cut and weight / inner diameter measurement processes.

For example, as shown by A in FIG. 4, the difference between the measured weight value and the optimum value is 0.5 g to 1.0 g.
Is determined, it is determined that one boring reference seat member 37 corresponding to 0.5 g is to be removed.

As shown by B, the difference from the optimum value is 1.
If it is within the range of 5 g to 2.5 g, it is determined that two boring reference seat members 35 corresponding to 1.0 g are to be removed.

As shown by C, the difference from the optimum value is 2.
If it is within the range of 5 g to 3.5 g, two boring reference seat members 35 corresponding to 1.0 g and 0.5 g
It is determined that one boring reference seat member 37 corresponding to g is to be removed.

Although not shown, the difference from the optimal value is the allowable upper limit plus the optimal value plus 1.5 g, and the adjustable range (total weight of all boring reference seat members 35 and 37). Optimum value that is the sum of 6.0 g and 7.5 g
Is exceeded, such a connecting rod 23 is excluded from the manufacturing process by a suitable means as a defective product. On the other hand, although not shown, if the weight value is lower than the allowable lower limit value of less than the optimum value minus 1.5 g, the weight value is similarly excluded from the manufacturing process as a defective product.

It should be noted that depending on the required adjustment accuracy, there is a case where no more strict adjustment is required as long as it is within the allowable value (the optimum value plus 1.5 g). In such a case, if the difference from the optimum value is within the allowable value of 1.5 g as shown by A, for example, it is determined that no adjustment is performed. If the difference is within the range of 1.5 g to 2.5 g, it may be determined that only one boring reference seat member 35 corresponding to 1.0 g is to be removed. Thereby, the subsequent weight adjustment step can be simplified. In addition, since the boring reference seat member 37 on the rod 21 is located in a portion that is relatively difficult to process, the boring reference seat member 37 is not used for adjustment, and adjustment is performed using only the boring reference seat member 35. It may be configured.

Based on the information on the processing location determined in this manner, finally, as a weight adjustment step, the boring reference seat member 35 or 37 at the determined location is cut from a position indicated by a substantially dotted line in FIG. Remove (S204-
2). For this cutting, not a numerically controlled machine tool capable of finely adjusting the cutting depth, but a simple processing device such as pushing off the boring reference seat member 35 or 37 with a hydraulically driven cutting tool, for example.

Finally, as described above, the weight and inner diameter of the connecting rod 23 after the weight adjustment are measured (S204-3), and if within the allowable value as a product, the above-described cleaning step (S2).
05), and shift to shipment.

As described above, in the present embodiment, of the plurality of boring reference seat members 35 and 37 used for clamping (pressing) when boring the large end hole 32 of the large end 29 of the connecting rod 23. The weight is adjusted by removing a desired number from the above. Therefore, it is not necessary to provide the weight adjusting boss 4 as in the prior art, and the weight of the connecting rod 23 and the entire engine can be reduced.

Since the amount of weight adjustment is increased or decreased by changing the number of boring reference seat members 35 and 37 to be shaved, the shaving amounts of the individual boring reference seat members 35 and 37 are finely adjusted. No need. Therefore, it is not necessary to use an expensive and large-scale numerically controlled machine tool for the shaving, and a simple processing device such as pushing out the boring reference seat members 35 and 37 with a hydraulically driven cutting tool is sufficient.

The boring reference seat members 35, 37
Is provided, the volume and cross-sectional area of each of the boring reference seat members 35 and 37 need only be small, and the stress generated when the boring reference seat members 35 and 37 are cut is reduced by the conventional single weight adjusting boss 4.
In this case, the loosening step (S103 in FIG. 7) for releasing the stress as in the related art becomes unnecessary, and the manufacturing process can be greatly simplified.

A boring machine and a honing machine for performing a finishing boring process and a finishing honing process are as follows:
Each of them is a device having a special structure, and it is structurally difficult to integrate functions of other processing machines (for example, a function of performing a loosening tightening process and a weight / inner diameter measuring process). Since the tightening step becomes unnecessary, the finishing boring step and the finishing honing step (S202, S20
After performing 3), the balance cutting step (S204) can be performed.
The function of performing the inner diameter measuring step can be integrated (S204), and both steps can be performed by one processing machine. Therefore, the number of processing machines required for the manufacturing process can be reduced,
There is an advantage that the transfer time and the transfer device can be saved.

Further, in the present embodiment, as a result of eliminating the conventional weight adjusting boss 4, the conventional balance cutting step (FIG. 7)
Large end hole diameter measurement step (S102-
Neither 1) nor the boss end surface height measurement (S102-2) is required.

In the present embodiment, of the plurality of boring reference seat members 35 and 37, some of the boring reference seat members 35 are heavy, and some of the other boring reference seat members 37 are heavy. Since the configuration is such that the weight is small, it is possible to finely adjust the weight by appropriately combining and shaving them as described above.

Although the boring reference seat members 35 and 37 are provided on both surfaces of the connecting rod 23 in the present embodiment, they may be provided on only one surface. Also,
Although the weight of the boring reference seat members 35 and 37 is configured so that the latter is half of the former, for example, the latter is 3% of the former.
It is also possible to consider various deformations such as two-half. Further, three or more different boring reference seat members having different weights may be provided. In addition, the configuration may be such that the boring reference seat members 35 and 37 to be removed are determined in consideration of maintaining the balance in the width direction and the thickness direction of the connecting rod 23, and such a configuration is also included in the scope of the present invention. Belong to.

[Brief description of the drawings]

FIG. 1 is a side view and a plan view of a connecting rod according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a manufacturing process of a connecting rod according to the embodiment of the present invention.

FIG. 3 is a flowchart showing details of a balance cutting / measuring process according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a weight distribution of a connecting rod and a weight adjustment amount in the embodiment of the present invention.

FIG. 5 is a plan view showing a conventional connecting rod.

FIG. 6 is a flowchart showing a conventional connecting rod manufacturing process.

FIG. 7 is a flowchart showing details of a conventional balance cutting step.

[Explanation of symbols]

1,21 rod, 2,22 cap, 3,23 connecting rod, 4 weight adjustment boss, 12,32 large end hole, 2
9 Large end, 35, 37 Reference seat member for boring.

Claims (3)

[Claims] 1. A weight measuring step for measuring the weight of a connecting rod before weight adjustment, and a vicinity of a large end hole at a large end of the connecting rod based on a measured value obtained in the weight measuring step and a predetermined target value. A step of removing a desired number of a plurality of boring reference seat members used for clamping when boring the large end hole. 2. A plurality of boring reference seat members, which are used for clamping at the time of boring the large end hole, are provided in the vicinity of the large end hole at the large end of the connecting rod. A connecting rod, wherein a predetermined weight unit to be used for adjusting the weight of the connecting rod is formed by removing a desired number of the plurality of boring reference seat members. 3. The connecting rod according to claim 2, wherein
At least some of the boring reference seat members among the plurality of boring reference seat members are heavy, and at least some of the other boring reference seat members are light in weight. Item 3. A connecting rod according to Item 2.