KR101175461B1

KR101175461B1 - Drawing plug of pipe material and drawing method employing the plug

Info

Publication number: KR101175461B1
Application number: KR1020107015501A
Authority: KR
Inventors: 가즈히로 우치다
Original assignee: 수미도모 메탈 인더스트리즈, 리미티드
Priority date: 2008-02-08
Filing date: 2008-11-10
Publication date: 2012-08-20
Also published as: JP2009184006A; JP4259603B1; TW200934595A; WO2009098808A1; CN101909776A; CN101909776B; KR20100092968A; TWI339599B

Abstract

A cold plug for inserting a thick tube in cold drawing, the plug being inserted into an inner surface of a pipe, having an outer surface continuously formed of a straight portion, a first tapered portion, and a second tapered portion in order from the tip of the plug, and having an outer surface of the straight portion. Has a cylindrical surface shape, and the tapered angle θ1 is given to the first tapered portion so that its diameter increases from the straight portion to the second tapered portion, and the diameter of the second tapered portion is directed toward the rear end from the second tapered portion. A taper angle θ2 is formed to increase, and by using a plug in which the taper angles θ1 and θ2 satisfy a relationship of θ1> θ2> 0 (zero), it is possible to prevent plug breakage and chatter defects from occurring.

Description

DRAWING PLUG OF PIPE MATERIAL AND DRAWING METHOD EMPLOYING THE PLUG}

TECHNICAL FIELD The present invention relates to a plug for drawing a pipe by cold working and a drawing method using the same, and more particularly, even when cold drawing is performed on a thick pipe of thick steel, It relates to a drawing plug having excellent drawing performance that does not cause chatter defects, and a drawing processing method of a pipe material using the same.

The drawing process of a pipe material is a processing method which obtains the pipe material excellent in dimensional precision and surface smoothness by carrying out axial diameter and thinning process by drawing out the small pipe which carried out the lubrication process through the plug and dice as a jig | tool. Processed pipe materials have high surface precision, and thus are mainly used as pipe parts for automobiles. In recent years, demands for high quality and high precision for automotive parts have been further increased, and demands are further expected. .

FIG. 1: is a figure explaining two types of drawing processes from which the plug to be used differs. FIG. Fig. 1 (a) shows a drawing process using a cylindrical plug 1 having a cylindrical surface having a constant outer diameter, and the rear end of the cylindrical plug 1 is connected to the supporting mandrel 5 and is concentric with respect to the die 4. It is inserted into the inner surface of the element pipe 6 so that it may become. The drawing process using the cylindrical plug 1 is used when manufacturing a comparatively large diameter pipe material. White arrows in the figure indicate the drawing direction.

FIG. 1 (b) shows the drawing process using the tapered plug 2, and likewise, the rear end of the tapered plug 2 is connected to the support mandrel 5, and is formed so as to be concentric with the die 4. 6) is inserted into the inner surface. The element pipe 6 is deformed along the conical tapered portion of the die 4 and the conical tapered portion of the plug 2, while the bearing portion of the die 4 and the cylindrical straight portion of the plug 2 are formed. It is guided between and processed into the process pipe | tube 7 which makes the inner diameter of the bearing part of the die 4 into an outer diameter, and makes the outer diameter of the straight part of the plug 2 into an inner diameter. Similarly, the white arrow in a figure has shown the drawing direction.

A taper angle θ is formed in the tapered portion of the tapered plug 2. For this reason, as a force acting on the taper plug 2, in addition to the frictional force in a drawing direction, the force which reverses to a drawing direction in the opposite direction to a drawing direction is added to the taper part of the plug 2, and the frictional force and the backing force cancel. For this reason, in the drawing process using the taper plug 2, the taper plug 2 may become a floating state in the drawing process, and the support mandrel 5 may become unnecessary. Moreover, even if the support mandrel 5 is connected, the force acting on the support mandrel 5 is reduced.

From this, the taper plug 2 shown in FIG. 1 (b) is called a semi-floating plug (SF plug), and has the above-described drawing characteristics, and thus is used for drawing a relatively small pipe. Hereinafter, the taper plug 2 shown to FIG. 1 (b) is called "SF plug" as needed.

It is a figure explaining the dice shape used for the drawing process of a piping material. The die 4 for drawing processing has the bearing part 4b of the exit side which determines the process outer diameter of an element pipe, and the approach part 4a which an internal diameter expands toward the entrance side for guiding a element pipe to the bearing part 4b. Have

In the dice shape shown in FIG. 2, the approach portion 4a is formed in a straight line, and has a predetermined die surface angle α. Usually, the die surface angle α is larger than the taper angle θ of the tapered plug shown in FIG. 1 (b) and becomes 20 to 25 deg.

By the way, the recent demand trend of the mechanical structural steel pipe applied to the automotive pipe part is increasing the demand of thick-size in addition to the request | requirement of the outer diameter size over various types. In the case of drawing the thick pipe of the thick pipe, the contact area between the plug face and the pipe is increased. For this reason, in the drawing process using a cylindrical plug, a plug becomes easy to draw in a drawing direction, a chatter vibration arises, and a chatter defect which is a trace corresponding to the vibration may generate | occur | produce.

On the other hand, in the drawing process using the SF plug, as the contact area between the straight portion and the tapered portion of the plug and the element pipe increases, the return force in the drawing direction or the reverse direction acting on the plug increases, so that the plug is in a floating state. It is also predicted that the deviating from or shifting from the proper position or drawing is performed. In this way, when the deviating from the proper position and the drawing process is carried out, not only the dimensional accuracy of the processing pipe is affected, but also the plug may be broken.

For this reason, at the time of drawing-out of a pipe | tube material, regardless of the thickness size of a pipe | tube, development of the drawing plug which is excellent in drawing performance which does not reduce a chatter defect or dimensional accuracy and does not damage a plug at the same time is requested | required. have.

Background Art Conventionally, various proposals have been made regarding plugs for drawing. For example, in Japanese Patent Application Laid-Open No. 09-225522, a tapered portion (denoted as an approach portion in the above document) and a straight portion (denoted as a bearing portion in the above document) are cut off portions (denoted as V-shaped grooves in the above document). The floating plug is proposed to be connected through. In addition, according to the plug proposed in the above document, since the elastic pressing force in the drawing direction is obtained by the cutout portion, the floating plug can maintain the balance at an appropriate position regardless of the thickness size of the element pipe.

Further, Japanese Patent Laid-Open No. 2003-112218 proposes a floating plug in which a tapered portion and a straight portion (denoted as a finish portion in the above document) are connected through a concave portion, and a thick plug used for a fuel injection pipe of a diesel engine, etc. I assume that it is suitable for the drawing processing of the scenery.

As mentioned above, in order to improve the yield of the processed product by cold working, and to prolong tool life, various drawing plugs are proposed, but not all of them appropriately improve the drawing performance of the drawing plug. .

The floating plug proposed in Japanese Patent Application Laid-Open No. 09-225522 is provided between a tapered portion and a straight portion in order to maintain a balance between a force in a drawing direction acting on the plug and a force acting in a direction opposite to the drawing direction. Although the narrow part is provided, it is not examined about the prevention of chatter defect and plug damage which are easy to produce when drawing thick pipes.

In addition, the floating plug described in Japanese Patent Laid-Open No. 2003-112218 has a predetermined space between the tapered portion and the straight portion in order to remove the bite eyes generated during internal cutting and to increase the smoothness of the inner circumferential surface of the pipe after the drawing process. Although the recess is provided in the positional relationship, the prevention of chatter defect and plug damage which are easy to generate | occur | produce when drawing thick pipes is pulled out.

This invention is made | formed in view of the problem in drawing process mentioned above, Even when cold drawing process of a thick pipe | tube is carried out, the occurrence of a plug damage, a chatter defect, and the fall of dimensional accuracy can be prevented effectively, and drawing performance is improved. An object of the present invention is to provide a plug for drawing a superior pipe and a drawing method using the same.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, this inventor observed the deformation | transformation behavior of the to-be-processed tube material in drawing process using the various drawing plugs.

It is a figure explaining the deformation | transformation behavior at the time of pulling out the thick tube of a thick body using a cylindrical plug. As described above, in the case of drawing the thick primary pipe 6, the contact area between the cylindrical plug 1 and the inner surface of the primary pipe 6 increases, so that the cylindrical plug 1 is easily drawn in the drawing direction, Chatter defects are generated by attracting self-excited vibrations that are repeated in and out of the plug face. When a chatter defect arises, a micro trace generate | occur | produces on the inner surface of the process pipe | tube 7 in an axial longitudinal direction.

It is a figure explaining an example of the deformation | transformation behavior at the time of pulling out the thick tube of a thick body using a SF plug. The SF plug 2 is inserted into the inner surface of the element pipe 6 so that the straight portion 2s is located concentrically with the bearing portion 4b of the die 4.

With the progress of the drawing process, the element pipe 6 is deformed according to the shape of the approach part 4a of the die 4 and the taper part 2t of the SF plug 2, and the bearing part of the die 4 It is led between 4b and the straight part 4b of the SF plug 2, and it is a shaft diameter and a thinning process, and the process pipe 7 is obtained.

Usually, in the initial stage of the deformation | transformation behavior of a drawing process, the small pipe | tube 6 is restrained by the approach part 4a of the die | dye 4, and makes thickening deformation, carrying out shaft diameter deformation according to the taper shape. At this time, if the primary pipe 6 is thick, thickening deformation of the primary pipe becomes remarkable, and the primary pipe 6 exceeds the interval between the approach part 4a of the die 4 and the taper part 2t of the SF plug 2. ) Inner surface abuts the rear end of the tapered portion (2t). When such a situation arises, a plug will be damaged with progress of drawing process.

In addition, in the case where the thick pipe is drawn out using the SF plug, the contact area between the machined surface of the SF plug 2 and the pipe 6 increases, so that the force acting on the SF plug 2 increases, In some cases, the SF plug 2 is displaced in the reverse direction to the drawing direction, does not float, or is displaced from an appropriate position. In order to prevent such a situation, it is necessary to make the axial length of the straight part 2s and the taper part 2t of the SF plug 2 appropriate.

This invention is completed based on the above-mentioned knowledge, Comprising: The drawing process plug of following (1) and (2), and the drawing process of (3) are the summary.

(1) an outer surface formed continuously with a straight portion, a first tapered portion, and a second tapered portion in order from the tip of the plug, wherein the outer surface of the straight portion is cylindrical in shape, and the first tapered portion has a diameter from the straight portion; A taper angle θ1 is provided to increase toward the second taper portion, and a taper angle θ2 is formed on the second taper portion such that its diameter increases from the second taper portion toward the rear end, and taper angles θ1 and θ2 are defined as follows (1). It is a plug for drawing processing of a pipe material characterized by satisfying the relationship of the formula.

θ1> θ2> 0 (zero). (One)

(2) The drawing plug of the pipe member of the above (1) further has a taper angle θ1 of the first tapered portion of 10 to 18 deg, and an axial length L1 of the first tapered portion and an axial length L2 of the second tapered portion. In this case, each relationship is characterized by satisfying the following formulas (2) and (3).

L1? (2)

L1 + L2? (3)

(3) A method of drawing and processing a pipe material by using a die having a predetermined bearing portion inner diameter and the pull-out plug according to any one of the above (1) or (2) to shaft diameter and thinning. .

Although the plug for drawing processing of this invention is optimal when a pipe material is thick, the thick in this invention means that the ratio (T / D) of thickness T with respect to outer diameter D is 20% or more.

According to the drawing plug of the pipe material of the present invention, even when cold drawing is performed using thick pipes, it is possible to effectively prevent the occurrence of plug breakage, chatter defects, and decrease in dimensional accuracy, thereby prolonging tool life. Can be. In the drawing processing method using this plug, the drawing performance is excellent, product defects due to the plug are reduced, and the product yield of the processing pipe can be improved.

FIG. 1: is a figure explaining two types of drawing processes in which the plug to be used differs, (a) shows drawing process using the cylindrical plug 1 comprised by the cylindrical surface shape with constant outer diameter, (b) taper plug Drawing process using (2) is shown.
It is a figure explaining the dice shape used for the drawing process of a piping material.
It is a figure explaining the deformation | transformation behavior at the time of pulling out the thick tube of a thick body using a cylindrical plug.
It is a figure explaining an example of the deformation | transformation behavior at the time of pulling out the thick tube of a thick body using SF plug.
It is a figure explaining the shape of the plug for drawing processing of this invention and the deformation | transformation behavior at the time of drawing using it.

The drawing plug of the pipe material of the present invention has an outer surface formed of a straight portion, a first tapered portion, and a second tapered portion in sequence from the tip of the plug. The outer surface of the straight portion has a cylindrical surface shape, and the first tapered portion. The taper angle θ1 is given so that the diameter thereof becomes larger from the straight portion to the second tapered portion, and the tapered angle θ2 is formed in the second taper portion so that the diameter thereof becomes larger from the second tapered portion toward the rear end. θ1 and θ2 satisfy a relationship of θ1> θ2> 0 (zero).

It is a figure explaining the shape of the plug for drawing processing of this invention and the deformation | transformation behavior at the time of drawing using it. As shown in FIG. 4, when the thick pipe is drawn out using an SF plug, at the initial stage of drawing, the pipe is reduced in diameter at the approach portion of the die and thickened. The plug comes into contact with the rear end of the tapered portion.

In order to prevent contact between the inner surface of the element pipe and the rear end of the tapered portion of the plug, the plug 3 for drawing according to the present invention has a conical surface having a taper angle θ1 from the cylindrical straight portion 3s toward the drawing direction. The first tapered portion 3t1 having a shape and the second tapered portion 3t2 having a conical surface having a taper angle θ2 are connected to each other.

And since the plug 3 for drawing of this invention makes the relationship of the taper angle of the 1st taper part 3t1 and the 2nd taper part 3t2 into (theta) 1> (theta) 2> 0 (zero), the element pipe (6) In addition to preventing the inner surface of the plug from coming into contact with the tapered portion 3t of the plug, the inner surface of the contacted tube can be exported according to the shape of the tapered portion 3t.

In the following description, the drawing plug of this invention may only be called "two-stage taper plug" as needed.

Specifically, as can be seen from the deformation behavior shown in FIG. 5, in the initial stage of drawing processing, even if the small pipe 6 is reduced in the approach portion 4a of the die 4 and thickened and deformed, the small pipe can be thickened. The inner surface of (6) comes into contact with either the first taper portion 3t1 or the second taper portion 3t2 of the two-stage taper plug 3. Also in subsequent drawing processing, the element pipe 6 is deformed according to the shape of the approach portion 4a of the die 4 and the taper portion 3t of the two-stage taper plug 3, and the die of the die 4 It is guided between the bearing portion 4b and the straight portion 3s of the two-stage tapered plug 3, and is subjected to shaft diameter and thinning.

The plug for drawing according to the present invention connects and installs the first taper portion 3t1 having the taper angle θ1 and the second taper portion 3t2 having the taper angle θ2 from the straight portion 3s. Even when thickened and deformed, the inner surface of the element pipe 6 is brought into contact with either the first tapered portion 3t1 or the second tapered portion 3t2.

Then, the relationship between the taper angles of the first tapered portion 3t1 and the second tapered portion 3t2 is θ1> θ2> 0 (zero), so that the inner surface of the element pipe is the first tapered portion 3t1 or the second tapered portion. When abutting on 3t2, the contact part can be sent out according to the shape of the tapered part 3t of the two-stage tapered plug 3, and the deformation of the element pipe 6 can be continued.

In the drawing plug of the present invention, it is preferable to set the taper angle θ1 of the first tapered portion to 10 to 18 deg in order to secure a floating state in the drawing process. Since the first taper portion receives a return force in a direction opposite to the drawing direction acting essentially on the plug, when the taper angle θ1 is less than 10 deg, a return force acting in the direction opposite to the drawing direction required for floating cannot be sufficiently obtained. The plug is likely to be pulled in and cannot keep floating. On the other hand, when the taper angle θ1 exceeds 18 deg, the inner surface of the element pipe contacts the rear end of the tapered portion, causing damage to the plug.

It is preferable that the plug for drawing processing of this invention makes axial length L1 of a 1st taper part 5 mm or more. In order to ensure a floating state in the process of drawing, when the axial length L1 is less than 5 mm, the pushing force which acts in the opposite direction to the drawing direction required for floating can not be obtained sufficiently, and a plug becomes easy to pull in.

In the drawing plug of the present invention, the total length of the axial length L1 of the first tapered portion and the axial length L2 of the second tapered portion is preferably 20 mm or less. In order to prevent damage to the plug, if the total length of the axial lengths L1 and L2 of the tapered portion of the plug exceeds 20 mm, the plug is likely to be broken during the drawing process.

The drawing method of this invention is a method of carrying out a shaft diameter and a thinning process to a to-be-processed pipe material using the die which has a predetermined bearing part internal diameter, and the above-mentioned drawing plug. Even in the case of drawing by using thick pipes, it is possible to effectively prevent the occurrence of plug breakage and chatter defects, thereby prolonging tool life and reducing product defects due to plugs. In this way, product yield can be improved.

EMBODIMENT OF THE INVENTION Hereinafter, the effect of this invention is demonstrated concretely based on an Example.

Example

As an open pipe, a pipe member made of S45C (0.44C-0.75Mn-0.15Cr-0.1Ti steel) specified in JIS G4051, which is a carbon steel pipe for mechanical structure, is prepared and drawn using various plugs. The processing was performed to evaluate the processing situation at this time. Drawing was made into five types of cold working schedules shown by Sch. 1-5 in Table 1 according to the prepared pipe size.

The section reduction rate Rd (%) shown in Table 1 is computed by following formula (4).

Rd = {(D ₀ -D ₁ ) / D ₀ } x 100 (%). (4)

However, D ₀ : Cross section before machining (mm ² ) D ₁ : Cross section after machining (mm ² )

[Table 1]

The plug used for drawing process was made into the cylindrical plug shown in the said FIG. 3, the SF plug shown in the said FIG. 4, and the two-stage taper plug shown in the said FIG. The dice used simultaneously set the taper surface angle α of the approach portion to 20 deg. The dimension of the used plug and the evaluation result at the time of drawing are shown in Table 2.

As a result of evaluation in Table 2, x mark shows the case where the drawing process was not possible, o mark shows the case where the drawing process was possible, and ◎ mark shows the case where the drawing process could be made stable. have.

[Table 2]

In drawing processing using a cylindrical plug, all were unstable drawing processing, but in particular, test No. When thick tube is attached like 2 and 3, a chatter defect generate | occur | produced and it was not able to process stably.

In drawing process using SF plug, test No. When using the normal T / D element pipe as shown in Fig. 4, the drawing process could be performed. When the thick tube was attached as shown in 5 and 6, the plug was broken and the drawing process could not be performed.

In drawing process using the two-stage taper plug of this invention, test No. All of 7-13 were able to perform stable drawing process. In particular, test No. 1 in which L1 and L2 fall within a preferable range. In the case of 9, 12, and 13, the outstanding processing characteristic was exhibited.

[Industrial Availability]

According to the drawing plug of the pipe material of the present invention, even when cold drawing is performed using thick pipes, it is possible to effectively prevent the occurrence of plug breakage, chatter defects, and decrease in dimensional accuracy, thereby prolonging tool life. Can be. In the drawing processing method using this plug, the drawing performance is excellent, product defects due to the plug are reduced, and the product yield of the processing pipe can be improved, and thus it can be widely applied as a method for producing a carbon steel pipe for mechanical structure.

Claims

A drawing plug inserted into an inner surface of a pipe member, the plug having an outer surface continuously formed by a straight portion, a first tapered portion, and a second tapered portion in order from the tip of the plug,
The outer surface of the straight portion is cylindrical in shape, the tapered angle θ1 is given to the first tapered portion so that its diameter increases from the straight portion toward the second tapered portion, and the diameter of the second tapered portion is the second tapered portion. Taper angle θ2 is formed to increase toward the rear end from
The taper angles θ1 and θ2 satisfy the relationship of the following formula (1),
In the case where the taper angle θ1 of the first tapered portion is 10 to 18 deg, and the axial length L1 of the first tapered portion and the axial length L2 of the second tapered portion are set, the respective relationships are given by the following formulas (2) and (3) Plug for drawing processing of the pipe material, characterized by satisfying the.
θ1>θ2> 0 (zero). (One)
L1? (2)
L1 + L2? (3)

delete

The method according to claim 1,
And a ratio (T / D) of the thickness T to the outer diameter D before the drawing of the pipe is 20% or more.

A shaft material and a thinning process are carried out using the dice | dies with a predetermined internal diameter of a bearing part, and the plug for drawing processes of Claim 1, The drawing process of the pipe material characterized by the above-mentioned.