JPH08132165A - Roll forming method - Google Patents

Abstract

PURPOSE: To generate no stepped part on the forming face in the cross rolling method to roll by plural forming steps while the reduction of area is made larger in sequence. CONSTITUTION: Two step forming parts 3, 4 are formed on the outer peripheral face of a pair of rollers 2, 2, after an intermediate diameter shaft W1 of prescribed width L1 is formed by a first step forming part 3, a small diameter shaft W2 of prescribed width L2 is formed while rolling the intermediate diameter shaft W1 by a second forming part 4. Further, in forming the second step small diameter shaft W2, the formed tapered face T1 of end part of intermediate shaft W1 is spreaded in the axial direction, the prescribed width L1 of intermediate diameter shaft W1 is set so that at completion of forming the formed tapered face T2 of end part of small diameter shaft W1 coincides with the formed tapered face T1 of end part of intermediate diameter shaft W1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a cross-rolling method for forming a round shaft by processing a round bar in a plurality of forming parts.

[0002]

2. Description of the Related Art Conventionally, when a stepped shaft is machined, a method of continuously roll-forming with a roller having a plurality of stages of forming and processing is disclosed, for example, in Japanese Patent Publication No. 57-133. No. 107949, and the like. That is, these are a pair of parallel rollers provided with a plurality of stages of molding processing on the outer peripheral surface facing each other, by inserting a heated material round bar in parallel with the roller shaft and rotating the roll in the relative direction. The diameter of the material sandwiched between the molding parts is gradually reduced.

[0003]

By the way, by successively working in a plurality of stages of forming and processing, the reduction rate of the cross-section is gradually increased, and finally the stepped shaft of one stage whose processing length is fixed becomes large. In order to mold at a cross-section reduction rate, it was necessary to introduce new technology. That is, the above Japanese Patent Publication Sho 57-1
In the case of No. 33, the purpose is to form two stepped shafts from the beginning, and in the case of JP-A-49-107949, the outer peripheral portion of the material is pushed in the axial direction at the first-stage forming part. Since the second stage molding is started during the unfolding and working, it was not possible to work with a very large reduction in area.

Further, if the second step is started after the processing by the first step forming section is finished, the section reduction rate can be relatively large. There has been a problem that a step is likely to occur at the joint between the second-stage molding and the second-stage molding. That is, as shown in FIG. 8, a medium diameter shaft W1 having molding slopes T1 and T1 at both ends as shown in (b) in the first stage of the forming material W0 is formed as shown in FIG. After molding, and then starting processing in the second-stage molding processing section as shown in (c), (d)
Push the peripheral meat in the axial direction as shown in (e),
Finally, when the small-diameter shaft W2 is formed in a desired length L2 in the intermediate portion, a step d is formed between the forming slope T1 at the end of the medium-diameter shaft W1 and the forming slope T2 at the end of the small-diameter shaft W2. It was necessary to perform a process such as removing the step d later. On the other hand, if the forming slope T2 of the small-diameter shaft W2 catches up with the forming slope T1 of the medium-diameter shaft W1 too early in the middle of the processing, there is a possibility that further machining cannot be performed.

[0005]

In order to solve the above-mentioned problems, the present invention is a method for forming a stepped shaft by a parallel roller having an outer peripheral surface having a plurality of steps of forming processing. In the roll forming method, in which the medium diameter shaft is formed in the processing part and then the small diameter shaft having a predetermined width and a predetermined diameter is formed while the medium diameter shaft is expanded in the second processing part, The forming width of the radial shaft is adjusted so that the forming slope of the end of the middle diameter shaft coincides with the forming slope of the end of the small diameter shaft when the forming of the second stage small diameter shaft is completed.

[0006]

[Function] When the small-diameter shaft W1 processed in the first-stage molding part is machined in the second-stage molding part to form the small-diameter shaft W2, the small-diameter shaft W2 in FIG. V2> V1 where V2 is the traveling speed of the forming slope T2 in the axial direction, and V1 is the traveling speed of the medium diameter shaft W1 along the extension in the axial direction of the forming slope T1.
Becomes Therefore, when the final length L2 of the small-diameter shaft W2 is determined, the width of the medium-diameter shaft W1 in the first step is machined to a certain length L1, and the setting of this L1 is set in the second step. At the time when the processing of the length L2 is completed in the molding processing section, just the molding slope T2
Set the length so that can catch up with T1.

[0007]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a roll forming die according to the present roll forming method, (A) is a front view, (B) is a perspective view, and FIG. 2 is a development view of a forming portion on the outer peripheral surface of the roll, and corresponding thereto. It is a process drawing which shows the shape change of the forming material W. The roll forming method of the present invention is applied, for example, as a forming method for processing a middle diameter of a round bar into a small diameter shaft at a large area reduction rate R of 0.8 or more for manufacturing a connecting rod. Molding is performed using a roll mold 1 as shown. The cross-section reduction rate R is a value calculated by R = (first cross-sectional area-final cross-sectional area) / first cross-sectional area × 100 (%).

The roll mold 1 is provided with a pair of rollers 2 and 2 whose roller axes are parallel to each other.
Two wedge-shaped forming parts 3 and 4 are provided respectively. The rollers 2 and 2 are arranged so as to face each other so that the molding portions 3 and 4 face in opposite directions, and the heated molding material W0 is inserted therebetween to rotate the rollers 2 and 2 a little less than one revolution (for example, 3).
(00 °) Rotate the middle part of the material W0 to the small diameter shaft W2
To process. Then, at this time, the medium-diameter shaft W1 is molded by processing the cross-section reduction rate of, for example, about 55 to 60% in the first-stage molding process portion 3, and then the medium-diameter shaft W1 is formed in the second-stage molding process portion. No. 4 is processed at a cross-section reduction rate of about 55 to 60% to form a small diameter shaft W2 having a large cross-section reduction rate of 80% or more in total. In other words, it is not possible to obtain a large cross-section reduction rate by one-time processing, so it is performed multiple times. In the figure, 5 and 5 are guides.

Here, the forming parts 3 and 4 will be described with reference to FIG. The first-stage forming part 3 is a biting part A1 that first bites into the forming material W0, a spreading part B1 that spreads the outer peripheral meat of the forming material W0 in the axial direction, and presses it to a predetermined length. After unfolding, flatten both ends in the axial direction Parallel part C1
In addition, the middle portion of the forming material W0 is processed into the medium diameter shaft W1 in the first stage molding processing portion 3, and the forming slopes T1 and T1 are formed at both ends of the medium diameter shaft W1. . Further, the second-stage forming part 4 axially spreads the engagement part A2 that engages with the medium-diameter shaft W1 from the start position of the parallel part C1 of the first stage and the outer peripheral meat of the medium-diameter shaft W1. It is provided with a push-out portion B2 and a final shape portion D2 for forming the final shape, and the middle-diameter shaft W1 is further processed into a small-diameter shaft W2 at the second-stage forming portion 4 and both end portions of the small-diameter shaft W2 are formed. The forming slopes T2 and T2 'are formed.

Further, the advance angles α of the first-step engaging portion A1 and the second-step engaging portion A2 are the same, and each of the engaging portions A1,
A2 and left and right slope forming parts a1 and a2 of the spread parts B1 and B2,
b1 and b2 have a plurality of slip preventing grooves m ... (...).
The same applies below. ) Is formed. The slip preventing grooves m ... Are rounded as shown in the sectional view of FIG. Further, as shown in FIG. 4 which is a sectional view taken along the line XX of FIG. 2, FIG. 5 which is a sectional view taken along the line YY of FIG. 2, and FIG. 6 which is a sectional view taken along the line ZZ of FIG. Slope forming parts b1, c1,
The angles β of b2 are all the same, and the left and right slope forming portions d2 and d2 'of the final shape portion D2 are asymmetrical so as to form an unequal angle. That is, the wide-angle-side non-conformal slope forming portion d
By 2 ', the slope (T2') having a shallow angle β'is formed.

By the way, the molding material W0 is processed into the final product shape Ws through the shape change as shown in FIG.
It is necessary to set the length L2 of the small-diameter axis W2 of the above to a specified standard value. In addition, the final product shape Ws forming slope T2,
It is necessary to take care so that no step is formed between T2 'and the molding slopes T1 and T1 at both ends of the medium diameter shaft W1. For that purpose, if the length L1 of the medium-diameter shaft W1 by the first-stage forming part 3 is processed to a certain constant value, the forming slope T is finally obtained.
1 and T2 can be matched. Then, the length of the medium diameter axis L1 which satisfies this is obtained.

Now, as shown in FIG. 7B, the forming material W is
The cross-sectional area of 0 is S0, the cross-sectional area of the medium diameter axis W1 is S1, the small diameter axis W2
The cross-sectional area of S2 is S2, and as shown in FIG.
The axial expansion length Δq is expanded (broken line) by the expansion part B2 (FIG. 2) of the forming part 4 of the step, and accordingly, the end e of the forming slope T1 and the end part f of the material W are Δq ′. If it is assumed that it has moved (broken line) (this assumption is not accurate exactly as described later), the following equation holds between Δq and Δq ′, and Δq> Δq ′. . .DELTA.q '=. DELTA.q.times. (S1-S2) / S1 ...

The reason is that the amount of meat removed (hatched portion) when the medium diameter shaft W1 is processed by Δq is approximately Δq × (S1
-S2), and this amount is the volume increase Δq '× S0 due to the movement of the material end f by Δq' and the forming slope T1.
The amount of reduction Δq ′ × (S0−S1) is approximately the same as the subtraction amount of the volume due to the movement of the end e of Δq ′. That is, Δq × (S1−S2) = Δq ′ × S0−Δq ′ × (S0
−S1) = S1 × Δq ′, and the above equation is obtained. Then, (S1−S2) / S1 is smaller than 1, and if Δq is further advanced, the forming slope T2 should catch up with the forming slope T1, and if the forming is completed at the time of catching (Δ
q = L2 / 2), and at the same time when the molding of the small diameter shaft W2 is completed, the molding slopes T1 and T2 coincide with each other and no step is formed.

Further, when the forming slope T2 finally catches up with T1, the initial lengths L1, Δq and Δq of the medium diameter axis W1 are obtained.
The relation of L1 / 2 + Δq ′ = Δq holds between
At this time, considering the equation and Δq = L2 / 2, L1 + L2 × (S1−S2) / S1 = L2, and the following equation holds. L1 = L2 * (1- (S1-S2) / S1) = L2 * S2 / S1 ...

By the way, to express the calculation result based on the above assumption more simply, the medium diameter axis W before machining is
It can be rephrased that the volume of one portion and the volume of the small diameter shaft W2 portion after machining are invariant (that is, L1 × S1 = L2 × S2), and in the case of Japanese Patent Publication No. 57-133, this assumption (before and after machining) It is specified that the volume of is unchanged). However, practical tests have revealed that the above assumption is not precisely correct. That is, in conclusion, it is necessary to multiply the above equation by the coefficient K (usually larger than 1), and the following equation holds.・ L1 = K × L2 × S2 / S1 ...

The reason for this is that the moving amounts of the end e of the forming slope T1 and the end f of the material W both assumed in FIG.
It seems that there is a problem in assuming q ', and it is considered that the movement amount of the end e of the forming slope T1 is smaller than the movement amount of the material W end f. That is, in other words, it is considered that not all of the volume of the medium diameter axis W1 is converted into the volume of the small diameter axis W2, but a part of the volume is buried in the forming slope T1 so as to rise. Therefore, in the present proposal, this coefficient K is obtained by an experiment, and L1 is obtained from the above equation.

By the way, in a concrete example of the present embodiment, a molding material W0 having a cross-sectional area S0 of 780 mm ² is finally used, and a small-diameter shaft W2 having a cross-sectional area S2 of about 140 mm ² (cross-section reduction rate of 82%).
When molding L2 = 70 mm, the medium diameter shaft W1
If the cross-sectional area S1 of is about 340 mm ² , the coefficient K is about 1.2.
5 and set the length L1 to about 36 mm.

The main forming method using the roll forming die 1 as described above will be described. First, the molding material W0 is heated and inserted between the rollers 2 and 2, and the rollers 2 and 2 are rotated in relative directions. Then, the medium-diameter shaft W1 having a predetermined length L1 is formed in the intermediate portion of the first-stage forming part 3. Then
In the second-stage forming part 4, processing is started from the center of the medium-diameter shaft W1 to form a small-diameter shaft W2 having a length L2. Then, the forming slope T2 at the end of the small-diameter shaft W2 has the medium-diameter shaft W
It merges with the molding slope T1 at one end and is leveled as the same slope, and thereafter, by further rotation of the rollers 2 and 2, the slope on one side is leveled to a shallow angle by the non-isometric slope forming part d2 '. . Although the sloped portions d2 and d2 'are made non-equal in the embodiment, it goes without saying that the same can be applied to the case where they are equi-angular.

[0019]

As described above, according to the roll forming method of the present invention, the medium-diameter shaft of a predetermined length is formed in the first-stage forming portion, and then the small-diameter shaft is formed in the second-stage forming portion. In the molding method that molds a total of one stepped shaft with a large cross-section reduction rate, by setting the processing length by the first step molding processing part to a predetermined value, the second step molding processing end At the same time, the forming slope of the end of the medium diameter shaft and the forming slope of the end of the small diameter shaft are made to coincide with each other, so that it is possible to efficiently perform processing with a large cross-section reduction rate.

[Brief description of drawings]

FIG. 1 shows a roll forming die according to the present roll forming method,
(A) is a front view, (B) is a perspective view

FIG. 2 is a development view of a molding processing portion on the outer peripheral surface of the roll and a processing step diagram showing a change in shape of the molding material W corresponding to the development processing portion.

FIG. 3 is a cross-sectional view of an anti-slip groove

FIG. 4 is a sectional view taken along line XX of FIG.

5 is a sectional view taken along line YY of FIG.

6 is a sectional view taken along line ZZ of FIG.

7A and 7B are explanatory views during molding, in which FIG. 7A is an explanatory view of a process in the axial direction, and FIG. 7B is an explanatory view of a cross-sectional area.

FIG. 8 is an explanatory diagram of a conventional molding process.

[Explanation of symbols]

1 ... Roll forming die, 2 ... Roller, 3 ... First stage forming part, 4 ... Second stage forming part, W0 ... Forming material, W1 ... Medium diameter axis, W2 ... Small diameter axis, T1 ... Medium diameter Shaping end of shaft end, T
2, T2 '... Shaping surface of small diameter shaft end.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kihara 1-10-1 Shin-Sayama, Sayama-shi, Saitama Prefecture Honda Engineering Co. (72) Inventor Ryuji Soga 1-10-1 Shin-Sayama, Sayama-shi, Saitama Within Da Engineering Co., Ltd.

Claims (1)

[Claims] 1. A method for forming a stepped shaft by means of parallel rollers having a plurality of stages of forming and processing on the outer peripheral surface, wherein a medium diameter shaft is formed by the forming and processing of the first stage and then the second stage. In a roll forming method in which a small-diameter shaft having a predetermined width and a predetermined diameter is formed by expanding the medium-diameter shaft in a forming portion, the forming width of the first-stage middle-diameter shaft is the second-stage small-diameter shaft. When the molding is completed, the roll forming method is characterized in that the forming slope at the end of the medium diameter shaft is formed in a length corresponding to the forming slope at the end of the small diameter shaft.