CN103769509B - The defining method of the land length of riffled tube internal mold and control method - Google Patents

Abstract

The invention discloses a kind of defining method of land length of riffled tube internal mold, it makes riffled tube internal mold land length Ls meet: Lmin≤Ls≤Lmax, Lmin=M+L', Lmax=M+L, and the optimum length of work strip is Lmin.The invention also discloses a kind of control method of riffled tube internal mold work strip, it, by controlling the thickness of pipe, reaches optimum length to make internal mold work strip.

Description

The defining method of the land length of riffled tube internal mold and control method

Technical field

The present invention relates to a kind of mould manufacturing method, particularly relate to the procedure in a kind of internal mold manufacture process of riffled tube.

Background technology

Riffled tube internal mold is used for the shaping of riffled tube internal whorl, and its core is the work strip of internal mold, namely deformed area.

Determine that the method for internal mold work strip is decided the position of work strip at present, the method can only judge the ideal position of drawing process and work strip by a large amount of test datas.This method makes institute's cycle time spent new product development stage long, and plays pendulum at beginning mass-production stage production tube sized data, and fail to draw more accurate data, the position of internal mold work strip can only control with operative employee's experience.In addition, the uncertain meeting of internal mold work strip position causes there is potential defect in the shaping process of tube plug drawing mill of optimized ribbed tubing, these defects are mainly manifested in that outside dimension is offscale, helical pitch large footpath bigger than normal, interior is less than normal, muscle wide bigger than normal, muscle is high not, draw time internal mold fracture or pipe is broken, screw thread convex tendon wire drawing etc.

The main cause of these defects above-mentioned is caused to have:

1. internal mold work strip is inadequate, and internal mold is little with flow of metal district contact surface, and extruding metal distortion is insufficient, and cause external diameter to act improperly, helical pitch is bigger than normal, and interior large footpath is less than normal, and muscle is wide bigger than normal, and muscle is high inadequate;

2. internal mold work strip is bigger than normal, and internal mold groove, laterally by dual torsion, easily makes internal mold fracture or pipe break.

Summary of the invention

An object of the present invention is to provide a kind of defining method of land length of riffled tube internal mold, it can determine work strip position best in riffled tube forming process, thus the generation of various cold-drawn defect in minimizing forming process, guarantee the qualified of finished product physical dimension.

Another object of the present invention is to provide a kind of control method of riffled tube internal mold work strip, it reaches optimum value by controlling pipe wall thickness to make internal mold work strip, thus both realized the generation reducing various cold-drawn defect in forming process, guarantee the qualified object of finished product physical dimension, realize again the object improving cold drawn forming difficulty.

In order to realize above-mentioned purpose of the present invention, the invention provides a kind of defining method of land length of riffled tube internal mold: the land length Ls of riffled tube internal mold is met:

Lmin≤Ls≤Lmax

Lmin=M+L'

Lmax=M+L

In formula, Lmin is the minimum land length of the interior theory of modules, and Lmax is interior theory of modules maximum functional strip length, and M is pitch, L' is the effective work strip correction of internal mold (namely in process of tube plug drawing mill, internal mold rotates the distance of shrinking toward plug direction), and L is the groove top width of internal mold on axial direction; And the optimum length of work strip is Lmin.

The technical program the land length Ls of internal mold is limited between Lmin and Lmax be because, inventor finds, desirable physical dimension is obtained to ensure that riffled tube is shaping, the lower limit of Ls must be Lmin, if and Ls is beyond Lmax, resistance suffered by metal flow can sharply strengthen, and core print possibility of stopping the rotation increases, and is very easy to cause internal mold to rupture or riffled tube is broken.

Further, the value of L' is 1-3mm.

According to another object of the present invention, present invention also offers a kind of control method of riffled tube internal mold work strip, it comprises the following steps:

(1) determine the optimum length Lmin=M+L' of internal mold work strip, wherein L' is the effective work strip correction of internal mold, and M is pitch;

(2) calculate physical length Ls=L+L'+ (the S0-S1)/tg θ of internal mold work strip, wherein L is the groove top width of internal mold on axial direction, and L' is the effective work strip correction of internal mold, and S0 is pipe wall thickness, and S1 is finished product wall thickness; θ is the angle of external mold approach cone;

(3) if Ls and Lmin is unequal, then pipe wall thickness correction value S0' is calculated according to following model:

S0'=tgθ（L _min-L-L'）+S1

(4) wall thickness of pipe is changed into S0' by S0, reach optimum length to make internal mold work strip.

Further, the value of L' is 1-3mm.

The defining method of the land length of riffled tube internal mold of the present invention, can ensure that internal mold land length makes the every size conforms technical requirement of production tube, ensure that the stability of the every size of finished product.

The more original control method of control method of riffled tube internal mold work strip of the present invention improves the accuracy of control data, control internal mold work strip position and effectively can improve the every physical dimension data of optimized ribbed tubing, and can to a certain degree reduce internal mold consumption.

Accompanying drawing explanation

Fig. 1 shows the work strip of internal mold in riffled tube forming process.

Detailed description of the invention

Now according to a particular embodiment of the invention, the application process of the technical program is further described.

As shown in Figure 1, when riffled tube 2 carries out cold-drawing technology, adopt the inwall of the shaping riffled tube of internal mold 1, the work strip of internal mold 1 is illustrated in figure 1 P.

Table 1 lists the specification of 31.8 × 5.5 and 38.1 × 8.3 two kinds of riffled tubes.

Table 1.

Embodiments of the invention will adopt internal mold and external mold to manufacture shaping above-mentioned two kinds of riffled tubes.In an embodiment of the present invention, the external mold of use is Chinese style, and groove top width (axis) L of internal mold is 5.6mm, pitch M be 16.8mm, lead angle α is 40 degree, and external mold approach cone θ is 13 degree, the calibrating strap Lo length 8mm of external mold.

Embodiment 1: the riffled tube of specification 31.8 × 5.5, shaping front specification 42 × 8.1, internal mold outer diameter D is 20.2mm

(1) the interior minimum land length Lmin of the theory of modules is calculated:

Lmin=M+L'=16.8+2=18.8mm；

Wherein L' is the effective work strip correction of internal mold, and namely in process of tube plug drawing mill, internal mold rotates the distance of shrinking toward plug direction, and general actual conditions correction is about 2mm;

(2) interior theory of modules maximum functional strip length Lmax is calculated:

Lmax=M+L=16.8+5.6=22.4mm；

(3) internal mold work strip physical length Ls is calculated:

Ls=L+L'+(S0-S1)/tgθ=5.6+2+(8.1-5.8)/tg13°=7.6+9.96≈17.6m

Wherein S0 is pipe wall thickness; S1 is finished product wall thickness.

From above-mentioned result of calculation, Ls < Lmin, that is internal mold work strip physical length Ls is less than the minimum land length Lmin of the interior theory of modules, but be greater than a pitch, this can cause riffled tube first half physical dimension to meet standard-required, and the every physical dimension of latter half requires to ensure.

If adjust internal mold position in actual production process, make internal mold recess outlet place exceed calibrating strap exit and be about 2mm, tube surface can be made again easily to occur, and spiral prints.Therefore desirable physical dimension data are obtained by increasing pipe wall thickness:

Ls′＝L+L'+(S0'-S1)/tgθ=Lmin

5.6+2+(S0'-5.8)/tg13°=18.8

S0'≈8.4mm

In the present embodiment, obtain desirable riffled tube by the wall thickness of pipe is increased to S0'=8.4mm.

Embodiment 2: the riffled tube of specification 38.1 × 8.3, shaping front specification 51 × 11.8, internal mold outer diameter D is 20.6mm

(1) the interior minimum land length Lmin of the theory of modules is calculated:

Lmin=M+L'=16.8+2=18.8mm；

Wherein L' is the effective work strip correction of internal mold, and namely in process of tube plug drawing mill, internal mold rotates the distance of shrinking toward plug direction, and general actual conditions correction is about 2mm;

(2) interior theory of modules maximum functional strip length Lmax is calculated:

Lmax=M+L=16.8+5.6=22.4mm；

(3) internal mold work strip physical length Ls is calculated:

Ls=L+L'+(S0-S1)/tgθ=5.6+2+(11.8-8.8)/tg13°=7.6+12.99≈20.6mm

Wherein S0 is pipe wall thickness; S1 is finished product wall thickness.

From above-mentioned result of calculation, Lmin≤Ls≤Lmax, therefore riffled tube is shaping can obtain desirable physical dimension, but in order to improve the difficulty of cold drawn forming, the present embodiment makes internal mold land length be optimum length Lmin, thus suitably reduces wall thickness further:

Lmin=L+L'+(S0'-S1)/tgθ

5.6+2+(SO'-8.8)/tg13°=18.8

SO'≈11.4mm

In the present embodiment, by the wall thickness of pipe is reduced to S0 '=11.4mm, to realize the dimensional requirement both meeting riffled tube, reduce again the difficulty of cold drawn forming.

It should be noted that above enumerate be only specific embodiments of the invention, obviously the invention is not restricted to above embodiment, have many similar changes thereupon.If all distortion that those skilled in the art directly derives from content disclosed by the invention or associates, protection scope of the present invention all should be belonged to.

Claims (4)

1. a defining method for the land length of riffled tube internal mold, is characterized in that, makes in riffled tube

Mould land length Ls meets:

Lmin≤Ls≤Lmax

Lmin＝M+L'

Lmax＝M+L

In formula, Lmin is the minimum land length of the interior theory of modules, and Lmax is interior theory of modules maximum functional strip length, and M is pitch, and L' is the effective work strip correction of internal mold, and L is the groove top width of internal mold on axial direction; And

The optimum length of work strip is Lmin.

2. the defining method of the land length of riffled tube internal mold as claimed in claim 1, it is characterized in that, the value of L' is 1 ~ 3mm.

3. a control method for riffled tube internal mold work strip, is characterized in that, comprises the following steps:

(1) determine the optimum length Lmin=M+L' of internal mold work strip, wherein L' is the effective work strip correction of internal mold, and M is pitch;

(2) calculate riffled tube internal mold land length Ls=L+L'+ (S0-S1)/tg θ, wherein L is the groove top width of internal mold on axial direction, and L' is the effective work strip correction of internal mold, and S0 is pipe wall thickness, and S1 is finished product wall thickness; θ is the angle of external mold approach cone;

(3) if Ls and Lmin is unequal, then pipe wall thickness correction value S0' is calculated according to following model:

S0'＝tgθ(L _min-L-L')+S1

(4) wall thickness of pipe is changed into S0' by S0, reach optimum length to make internal mold work strip.

4. the control method of riffled tube internal mold work strip as claimed in claim 3, it is characterized in that, the value of L' is 1 ~ 3mm.