JP2014046333A - Spinning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spinning method that eliminates the port stretch of a pipe end actualized due to thinning of materials and high constriction rate, and shape defects such as the folds associated with the above.SOLUTION: A spinning method relating to the present invention is characterized by operating a roll shape tool 5 so that ΔR(in) is larger than ΔR(out), where the ΔR(out) is the total sum of a diameter reduction amount obtained by diameter reduction using an out-pass in which a roll shape tool 5 moves from a clamp 3 side of a metal pipe 1 toward a pipe end side, and the ΔR(in) is the total sum of a diameter reduction amount obtained by using an in-pass in which the roll shape tool 5 moves from the pipe end side to the clamp 3 side.

Description

  The present invention relates to a spinning method for processing a reduced diameter portion at an end portion of a pipe.

Automobile exhaust parts use mufflers and chamber-like parts with narrowed air chambers, such as converters.
Conventionally, these parts have been made by assembling several parts made by pressing a plate-shaped material by welding, but in recent years, as shown in FIG. The type to do is increasing.
Spinning can create parts with different shapes by changing the operation pattern of a roll-shaped tool, which eliminates the need for a mold for each part and has an advantage in terms of cost.

As a prior art for reducing the diameter of the end of a metal tube by spinning, for example, “a manufacturing method of a catalytic converter container and its manufacturing apparatus” disclosed in Patent Literature 1 and “a spinning processing method” disclosed in Patent Literature 2 There is.
In the technique disclosed in Patent Document 1, the forming roller is moved in the axial direction and the radial direction of the base material pipe while holding the base material pipe and rotating it around its axis.
On the other hand, the “spinning method” disclosed in Patent Document 2 includes a plurality of roll shapes that grip one end of a metal tube and reciprocate in the axial direction of the metal tube while revolving around the central axis of the metal tube. The diameter of the metal tube is reduced by pressing the tool against the metal tube (hereinafter referred to as “work fixing type spinning process” in this specification).

Recently, since it is excellent in processing efficiency, the workpiece fixing type spinning processing method described in Patent Document 2 has been widely performed, and the present invention also relates to such a workpiece fixing type spinning processing method.
In the spinning process, the formability changes depending on the diameter, thickness, and material of the metal material (tube to be processed), so the diameter-reduced part may be locally thinned, depending on the required specifications of the product. Care must be taken in setting the operation pattern of the roll-shaped tool.
Therefore, in Patent Document 2, as the processing conditions given to the processing roller, the feed rate in the axial direction of the processing tube, the number of processing passes, and the number of rotations are set so that the contact between the processing roller and the processing tube is reduced. This reduces the number of times the work tube is ironed by the processing roller and reduces the number of times the tensile stress acts on the tapered portion, so that local reduction in the thickness of the tapered portion can be suppressed (patent) (Refer to paragraph 2 of reference 2).

JP 2000-179334 A JP 2009-195942 A

In recent years, in order to reduce the weight of automobiles, the use of thin metal pipes in exhaust system parts has been increasing. As a result, a relatively large-diameter and thin-walled metal tube is reduced in diameter, and a shape defect phenomenon that has not been reduced as intended has become apparent.
In particular, the shape defect at the end of the metal tube is a problem, and FIGS. 4B and 4C show examples of such a shape defect event at the tube end. FIG. 4B shows a shape failure phenomenon in which the actual diameter is large with respect to the product diameter targeted by the operation of the roll-shaped tool, and the diameter reduction processing is not achieved. Since the diameter of the tube does not reach the tip of the tube, the end is shaped like a trumpet. In minor cases, it is possible to obtain a product by correcting the operation pattern of the roll-shaped tool in anticipation of the mouth opening, or by cutting the tip after diameter reduction processing, but the diameter reduction rate from the raw tube to the product shape is particularly high The larger the size, the more likely it is to occur. In severe cases, it may be folded into a pleat as shown in FIG.

As a countermeasure against the above-mentioned shape defect occurring at the end of the metal tube as described above, Patent Document 1 cannot cope with it, and a countermeasure has been desired.
That is, the present invention provides a spinning method that does not cause a shape failure phenomenon such as a widening of a pipe end that has become obvious due to a thin metal tube and a high diameter reduction rate, and a folding wrinkle associated therewith. The purpose is to do.

  As described above, the workpiece fixing type spinning process is performed by revolving around the central axis of the metal tube while holding the one end side of the metal tube of the workpiece by the clamp and pressing the roll-shaped tool against the metal tube. The metal tube is reduced in diameter by reciprocating in the axial direction. A series of processing steps sequentially include an operation from the clamp side to the pipe end side (hereinafter referred to as “out path”) and a reverse operation from the pipe end side to the clamp side (hereinafter referred to as “in pass”). By repeating the process, the diameter reduction process sequentially proceeds to finally reach the target diameter reduction radius.

  It is well known to those skilled in the art that, in the workpiece fixing type spinning process, the tube end portion is a free end without restraint, so that shape defects are likely to occur. For this reason, it is general that the diameter reduction amount in the out pass is set to be larger than the diameter reduction amount in the in pass because it is not preferable to use the pipe end as the processing start point.

The inventor examined the cause of the occurrence of a defective shape event at the pipe end in the general operation process as described above.
Since the material is stretched in the axial direction in the out pass depending on the direction of operation of the roll-shaped tool, the increase in the diameter of the pipe end reduced diameter portion is smaller than that in the in pass. For this reason, when the amount of diameter reduction in the out path increases, the shape of the tube end portion is easily bent, and this tendency becomes remarkable at the tube end portion with less restraint. When machining proceeds in such a state, the roll-shaped tool will bend and escape when the roll-shaped tool passes, and the set diameter reduction deformation will not be achieved. Although the amount of deviation from such a setting is slight in each pass, it is considered that the amount of deviation from the setting is accumulated over the entire process consisting of a plurality of passes, and becomes apparent as the mouth opening of the tube end.

The inventor believes that the above-mentioned shape defects are caused by accumulation of divergence amounts due to paths that increase the diameter reduction amount in the out path. The knowledge that it can prevent effectively was acquired.
The present invention is based on such knowledge, and specifically has the following configuration.

(1) A spinning method according to the present invention is a roll-shaped tool that uses a metal tube clamped at one end as a workpiece, revolves around the central axis of the metal tube, and reciprocates in the axial direction of the metal tube. A spinning process for reducing the diameter of the metal pipe by pressing the metal pipe against the metal pipe,
ΔR (out) is the total amount of diameter reduction processing that reduces the diameter of the pipe end by the out path where the roll shape tool moves from the clamp side to the pipe end side of the metal pipe. The roll-shaped tool operates so that ΔR (in) is greater than ΔR (out) when the sum of the diameter reduction processing of the pipe end due to the in-pass moving from the part side to the clamp side is ΔR (in) It is characterized by making it.
When the above relationship is expressed by a mathematical expression, 0.5 ≦ ΔR (in) / {ΔR (in) + ΔR (out)}.

(2) Further, in the above described (1), the diameter reduction processing is performed in which the pipe end is reduced by each out path in which the roll-shaped tool moves from the clamp side to the pipe end side of the metal pipe. When the amount is Δr (out), and the roll shape tool is continuously reversed and the roll end tool moves from the tube end side to the clamp side, the diameter reduction processing amount of the pipe end by each in pass is Δr (in). The roll-shaped tool is operated so that the path diameter reduction amount {Δr (in) + Δr (out)} satisfies 0.3 ≦ Δr (in) / {Δr (in) + Δr (out)}. Is.

  In the present invention, ΔR (out) is the total amount of diameter reduction processed by the out path in which the roll-shaped tool moves from the clamp side of the metal tube toward the tube end side, and the roll-shaped tool is By operating the roll-shaped tool so that ΔR (in) is greater than ΔR (out), where ΔR (in) is the sum of the diameter reduction amount due to the in pass moving from the end side to the clamp side In addition, it is possible to provide a spinning method that prevents the occurrence of a defective shape phenomenon such as a mouth widening of the tube end that has become apparent due to the thinning of the material and the increase in the diameter reduction ratio, and the accompanying wrinkles.

It is explanatory drawing for demonstrating the spinning processing method which concerns on one embodiment of this invention. It is an AA arrow line view of FIG. It is explanatory drawing explaining operation | movement of the roll-shaped tool in the spinning processing method which concerns on one embodiment of this invention. It is a figure for demonstrating the edge part of the metal pipe after a spinning process.

FIG. 1 is an explanatory view for explaining a spinning method according to an embodiment of the present invention, and is an elevational sectional view passing through the central axis of the metal tube 1 when the clamp 3 grips the metal tube 1. is there.
In the spinning method according to the present embodiment, one end side of a metal tube 1 to be processed is held by a clamp 3, and, for example, three roll-shaped tools 5 are revolved around the central axis of the metal tube 1, and the metal tube The metal tube 1 is reduced in diameter by being pressed against the metal tube 1 while reciprocating in the axial direction of 1.

One end side of the metal tube 1 is inserted into the clamp 3 to hold the metal tube 1 in a fixed state.
As shown in FIGS. 1 and 2, the roll-shaped tool 5 has a rounded outer peripheral portion, and a rotation shaft 7 is inserted in the center thereof, so that the roll shape tool 5 is rotatable around the rotation shaft 7. It has become.
As shown in FIG. 2, for example, three roll-shaped tools 5 are arranged so that the centers of the rotation shafts 7 of the roll-shaped tool 5 are concentric with the metal tube 1 and at equal intervals.
The roll-shaped tool 5 can revolve around the central axis of the metal tube 1 by a rotation mechanism (not shown) (see arrow a in FIG. 2), and can reciprocate in the axial direction of the metal tube 1 by a reciprocation mechanism (not shown). It can be moved in the radial direction of the metal tube 1 by a diameter reducing mechanism (not shown) (see arrow b in FIG. 2). Three roll-shaped tools 5 are integrated to perform the same operation as described above.
The roll-shaped tool 5 can perform the above three types of operations independently. And by changing and combining each operation | movement of a reciprocating movement and a movement to radial direction, the track | orbit (path) of the roll-shaped tool 5 can be made into various things.

In the spinning method according to the present embodiment, the path of the roll-shaped tool 5 is a combination of reciprocation and movement in the radial direction, as indicated by an arrow d in FIG. FIG. 3 is an explanatory diagram for explaining in more detail by extracting only the arrow d in FIG.
Hereinafter, the path of the roll-shaped tool 5 will be described in detail with reference to FIG.
In FIG. 3, the left side is the clamp 3 side, and the right side is the tube end side. The thick arrow in FIG. 3 indicates an out path that is a trajectory from the clamp 3 side to the tube end side, and the dotted arrow indicates an in path that is a trajectory from the pipe end side to the clamp 3 side.

As shown in FIG. 3, the out path in the present embodiment is a trajectory that moves in the axial direction from the clamp 3 side toward the tube end side. The diameter reduction processing amount in the out path is represented by Δr (out) below.
In the final stage of the out pass, the roll-shaped tool 5 moves to a position beyond the pipe end, and then moves in the diameter reducing direction as indicated by a thin line arrow in FIG. The amount of movement at this time corresponds to the amount of diameter reduction in the in-pass, and is represented by Δr (in) below.
After moving in the diameter reducing direction, the roll-shaped tool 5 moves from the tube end side toward the clamp 3 side (in-pass) as shown by a dotted arrow in FIG.
As described above, the out path, the movement in the diameter reducing direction, and the in path constitute a path for one reciprocating movement of the roll-shaped tool 5. This one-time movement is referred to as a round-trip path in the following description. By repeating such a reciprocating pass a plurality of times, the diameter reduction processing of the metal tube 1 proceeds sequentially and finally reaches the target diameter reduction radius.

The diameter reduction amounts Δr (out) and Δr (in) are amounts relative to the radius, and in terms of diameter, they are double the amount of diameter reduction (Δr (out) × 2, Δr (in) × 2). The diameter will be reduced.
In the following description, in the n-th round-trip pass, n is added as a subscript to the diameter reduction processing amount and expressed as Δr _n (out) and Δr _n (in). For example, in the first round trip, they are expressed as Δr ₁ (out) and Δr ₁ (in).

Next, a specific example of the method for reducing the diameter of the metal tube 1 will be described together with the operation of the roll-shaped tool 5.
First, the roll-shaped tool 5 is held by the metal tube 1 by gripping the metal tube 1 with the clamp 3 and positioning the roll-shaped tool 5 (refer to arrow a in FIG. 2) revolved by the rotation mechanism at the diameter reduction processing start position S. 1 is contacted. At this time, since the roll-shaped tool 5 is rotatable, it rotates in the same direction as the revolution direction (see arrow e in FIG. 2).

Next, as shown in FIG. 3, the roll-shaped tool 5 starts the out pass of the first reciprocating pass, and the metal tube 1 is reduced in diameter by Δr ₁ (out) with respect to the original diameter.
Then, it moves to a position slightly beyond the tube end along the tube axis toward the tube end. By this out pass, the metal tube 1 is reduced in diameter by Δr ₁ (out) to the end of the tube.

The roll-shaped tool 5 moves in the diameter reducing direction by Δr ₁ (in) at a position beyond the pipe end.
Next, the roll-shaped tool 5 moves by a predetermined distance from the tube end side toward the clamp 3 side. At this time, the diameter of the metal tube 1 is reduced by Δr ₁ (in). This completes the first round-trip pass.

After that, the second round-trip pass, the third round-trip pass, etc., and the round-trip pass as described above are repeated a predetermined number of times. Reach. The total diameter reduction after machining (the difference between the radius before diameter reduction and the radius after machining) must be equal to the sum of the diameter reduction quantities Δr _n (out) and Δr _n (in) of all reciprocating passes. become.
In the following description, the sum of the diameter reduction processed by the out path is ΔR (out) (= Δr ₁ (out) + Δr ₂ (out) +...), And the roll-shaped tool 5 is connected to the pipe end. The total amount of diameter reduction processing by the in pass moving from the part side to the clamp 3 side is assumed to be ΔR (in) (= Δr ₁ (in) + Δr ₂ (in) +...). The total diameter reduction amount is represented by {ΔR (in) + ΔR (out)} when expressed by ΔR (out) and ΔR (in). In terms of the diameter after the diameter reduction processing, the diameter is reduced by twice the total diameter reduction processing amount from the diameter before the diameter reduction processing.

  The spinning method according to the present invention improves the workability by operating the roll-shaped tool 5 so that the above ΔR (in) accounts for more than half of the total diameter reduction processing amount. The basis for making ΔR (in) account for more than half of the total diameter reduction processing amount will be described based on the results of Experiment 1 below.

Experiment 1 shows the ratio of ΔR (in) to the total diameter reduction amount (hereinafter referred to as “ΔR (in) total diameter reduction ratio”) when the pipe end is reduced to a predetermined target radius. The radius after processing (hereinafter referred to as “result radius”) is measured and compared. At this time, the shape of the tube end was also observed.
As a method for defining the ΔR (in) total diameter reduction ratio, in Experiment 1, the ratio of Δr _n (in) to {Δr _n (in) + Δr _n (out)} in each round-trip path (hereinafter referred to as “Δr (in ) "Reduction ratio") is set to be the same as the total reduction ratio of ΔR (in) in all round-trip passes.

As the metal pipe 1, a ferritic stainless steel pipe having a radius of 55 mm (diameter: 110 mm) and a plate thickness of 1.0 mm was used. The target radius was 27.5 mm (diameter 55 mm, diameter reduction rate 50%), and the diameter was reduced by 8 reciprocations to the target radius. The ΔR (in) total diameter reduction ratio was 0.85 for condition A, 0.80 for condition B, 0.65 for condition C, 0.55 for condition D, 0.50 for condition E, 0.45 for condition F, and 0.40 for condition G.
Table 1 summarizes the above conditions and the results after the diameter reduction processing.

Table 1 shows the set radius (mm), diameter reduction (mm) and Δr (in) reduction ratio of the out path and in path in the n-th round trip for each of conditions A to G, and ΔR (in) for each condition. The total diameter reduction ratio, actual radius (mm), and deviation (%) from the target radius are shown.
As shown in Table 1, the deviation from the target radius was as good as less than 1% up to conditions A to E where the ΔR (in) total diameter reduction ratio was 0.5 or more. In particular, the conditions A to C where the ΔR (in) total diameter reduction ratio is high were not deviated, and very good processing was possible.
On the other hand, in the condition F and the condition G where the ΔR (in) total diameter reduction ratio is less than 0.5, in the condition F, the divergence is 5.02%, and the workability is abruptly deteriorated. It was a problem with wrinkles.

  As described above, when the ΔR (in) total diameter reduction ratio is less than 0.5, the difference between the target radius and the actual radius increases rapidly, and a remarkable mouth spread or a wrinkle shape is formed. In FIG. 5, the ΔR (in) total diameter reduction ratio is set to 0.5 or more.

In the above, the Δr (in) reduction ratio in each round-trip path is fixed. However, if the above-mentioned ΔR (in) total reduction ratio is 0.5 or more, the in-path is out in a certain round-trip path. It may be made smaller than the path. The reason for this will be described.
As described above, the amount of divergence at the pipe end in each out pass is small, and as a result of accumulating all the processes to the last, it becomes manifest as a shape defect, so ΔR (in) becomes {ΔR ( If the ratio of in) + ΔR (out)} is more than half, the shape defect does not occur.
However, the Δr (in) diameter reduction ratio is not limited and may be small, and is preferably set to 0.3 or more. Hereinafter, this reason will be described based on the result of Experiment 2.

In Experiment 2, as in Experiment 1, the value of ΔR (in) total diameter reduction ratio was changed when the pipe end was reduced to a predetermined target radius. In addition, the Δr (in) diameter reduction ratio in each round-trip path was changed to various values. And after processing, the performance radius was measured and compared. The shape of the tube end was also observed.
In Experiment 2, the metal pipe 1 was a ferritic stainless steel pipe having a radius of 63 mm (diameter 126 mm) and a plate thickness of 1.2 mm. The target radius was 30 mm (diameter 60 mm, diameter reduction rate 52.4%), and the diameter reduction processing was performed in 8 reciprocations to the target radius. The ΔR (in) total diameter reduction ratio was set to 0.51 in the condition H, 0.55 in the condition I, 0.66 in the condition J, and 0.68 in the condition K so as to be 0.5 or more in all conditions. Further, the Δr (in) diameter reduction ratio was changed between 0.25 and 0.88.
Table 2 summarizes the above conditions and the results after the diameter reduction processing.

As shown in Table 2, since ΔR (in) total diameter reduction ratio was 0.5 or more under all conditions, the deviation was less than 1%, and good results were obtained. In particular, the condition J and the condition K in which all Δr (in) diameter reduction ratios were 0.3 or more were very good with no difference.
As described above, it was found that if the ΔR (in) total diameter reduction ratio is 0.5 or more and the Δr (in) diameter reduction ratio is 0.3 or more, the workability is further improved.
In addition, said embodiment is an example to the last, Comprising: The structure of this invention is not limited.

Since Experiment 3 for confirming the effect of the spinning method of the present invention was performed, this Experiment 3 will be described below. Since Table 3 is the same as Table 1 and Table 2, description of how to read the table is omitted.
In Experiment 3, a ferritic stainless steel pipe having a radius of 60 mm (diameter 120 mm) and a plate thickness of 1.5 mm was used as the metal pipe. The target radius was 25 mm (diameter 50 mm, diameter reduction rate 58.3%), and the diameter was reduced by 10 reciprocations to the target radius.
The ΔR (in) total diameter reduction ratio was set to 0.51 for both the condition M and the condition N, and to a value satisfying 0.5 or more as described in the above embodiment. The Δr (in) diameter reduction ratio is changed from 0.2 to 0.7. Under the condition N, as described in the above embodiment, the Δr (in) diameter reduction ratio of all reciprocating passes is 0.3 for the purpose of further improving the workability. It was made to become above. Further, using the condition L as a comparative example, the processing was performed with the ΔR (in) total diameter reduction ratio set to 0.4.
Table 3 summarizes the above conditions and the results after the diameter reduction processing.

  As shown in Table 3, under the condition L, folding wrinkles occurred. On the other hand, in the condition M in which the ΔR (in) total diameter reduction ratio was 0.5 or more, the deviation from the target radius was as small as 0.92%, which was a favorable result. Furthermore, the deviation was 0.24% under the condition N where the Δr (in) diameter reduction ratio was 0.3 or more, which was a better result.

  As described above, according to the spinning processing method of the present invention, there is a problem of shape defects such as the mouth widening of the pipe end that has become apparent due to the thinning of the material and the increase in the diameter reduction rate, and the folding wrinkles associated therewith. Does not occur.

a to e Arrow S Reduction diameter start position 1 Metal tube 3 Clamp 5 Roll-shaped tool 7 Rotating shaft

Claims (2)

A metal tube clamped at one end is used as a workpiece, and the metal tube is compressed by pressing a roll-shaped tool that revolves around the central axis of the metal tube and reciprocates in the axial direction of the metal tube against the metal tube. A spinning process for diameter processing,
ΔR (out) is the total amount of diameter reduction processing that reduces the diameter of the pipe end by the out path where the roll shape tool moves from the clamp side to the pipe end side of the metal pipe. The roll-shaped tool operates so that ΔR (in) is greater than ΔR (out) when the sum of the diameter reduction processing of the pipe end due to the in-pass moving from the part side to the clamp side is ΔR (in) Spinning method characterized in that   The roll diameter tool is reduced by Δr (out), and the roll shape tool is continuously reversed by each out pass where the roll shape tool moves from the clamp side to the pipe end side of the metal pipe. Is the diameter reduction processing amount of each reciprocating path {Δr (in) + Δr (out) where Δr (in) is the diameter reduction processing amount of the pipe end by each in pass moving from the pipe end side to the clamp side 2. The spinning method according to claim 1, wherein the roll-shaped tool is operated so that} satisfies 0.3 ≦ Δr (in) / {Δr (in) + Δr (out)}.

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