CN103357743A - Process method for hole punching of multi-station progressive die - Google Patents

Abstract

The invention discloses a process method for hole punching of a multi-station progressive die. The multi-station progressive die comprises puncher pins, a material pressing device and the lower die plate, the lower die plate is provided with a concave die and is not provided with a concave die corresponding to the puncher pins and the material pressing device respectively, and when processing materials carries out progressive operations along the lower die plate in the multi-station progressive die, the process method comprises the steps that 1, the first puncher pin punches the processing materials with a thickness t, the depth s of the puncher pin enables the processing materials to form an upper concave portion and a lower convex portion, and the puncher pin withdraws; 2, the convex portion is pressed back to the processing materials through the material pressing device and the lower die plate; 3, the second puncher pin punches the concave position of the processing materials in the first step again, and the convex portion is punched, and a small hole is formed. The process method has the advantages that punching is carried out on the small hole twice or more times, the maximum length enabling a convex die to be bent and to be steady is increased, the hole size limit of conventional hole punching is indirectly reduced, that is, a convex die with a small section can be adopted when holes with identical sizes are punched, and breakage does not easily occur.

Description

A kind of process of multistation progressive die stamping-out aperture

Technical field

The invention belongs to the mould punching method, be specifically related to a kind of process of multistation progressive die stamping-out aperture.

Background technology

Rush aperture in the cold punching die, just refer to the punching aperture less than or close to the stamping-out of material thickness, in engineering, the type of aperture has four kinds of (a), (b), (c), (d) as shown in Figure 1.When rushing aperture; punch very easily fractures; by analysis; the destruction trend of rushing Pinhole Punch belongs to the strut buckling problem; for making punching die obtain normal service life, check the hole dimension limit of not taking protective measure to carry out conventional punching of determining according to compression and be shown in Table 1, namely; as long as orifice size is less than the tabular size in the product, can not directly adopts processing method for stamping and obtain.

Table 1 is not taked protective measure and the hole dimension limit of carrying out conventional punching

Material	Fig. 1 (a)	Fig. 1 (b)	Fig. 1 (c)	Fig. 1 (d)
					08,10, Q235, Q255 steel:	d≥t	a≥0.9t	a≥0.7t	a≥0.8t
25,35,45, Q275 steel:	d≥1.3t	a≥1.2t	a≥0.9t	a≥t
					60si2Mn、T12A	d≥1.5t	a≥1.35t	a≥1.1t	a≥1.2t
Brass, copper	d≥0.9t	a≥0.8t	a≥0.6t	a≥0.7t

In order to reach at the needs of product processing less than the listed limit aperture of table 1; usually adopt at present two kinds of methods on the engineering: first; the structure that adds protective sleeve to punch; as shown in Figure 2; employing adds the structure of protective sleeve 2 to punch 1; owing to having increased the cross section inertia distance of punch; small punch has almost lost buckling deformation even the possibility that fractures; so that the punch of same length can obtain the punching than table 1 smaller szie; but; the orifice size that this method obtains is also still limited, because the restriction that reduces finally also to be subjected to the punch material compression strength limit of punching hole diameter.Second method is to adopt step punch 1, as shown in Figure 3, punch is divided into multistage (three sections or four sections) from length direction, reduce piecemeal from top to bottom the cross section of punch, nethermost one section ability matches fully with Male Die Size, and this method has increased the cross section inertia distance of punch equally, has reduced the possibility that the small punch buckling deformation fractures, equally also can obtain the punching than table 1 smaller szie, but effect is slightly poorer than first method.Above-mentioned two kinds of methods are no matter in single operation cold-punching mould or the processing of the aperture of multistation progressive die, all be widely used.

Summary of the invention

The purpose of this invention is to provide the not process of the multistation progressive die stamping-out aperture of frangibility of a kind of punch.

The technical scheme that realizes the object of the invention employing is as follows:

The process of multistation progressive die stamping-out aperture provided by the invention, be to comprise drift, material pressing device and correspondingly with drift and material pressing device respectively establishing die and do not establish in the multi-station progressive die of lower bolster of die, carry out according to the following steps when rapidoprint is grading along lower bolster:

The first step, the first drift pour in the rapidoprint that thickness is t, and the degree of depth s of drift makes rapidoprint form top recess and following protuberance, withdraws from drift;

Second step, material pressing device and lower bolster push back protuberance in the rapidoprint;

In the 3rd step, the second drift pours on the rapidoprint in the recess location in the first step again, and protuberance is washed out the formation aperture;

Perhaps repeat as required to carry out for the 3rd step again after first and second step;

Rapidoprint when grading along lower bolster by elastomeric element jack-up, so that it sends next station to smoothly in the situation that protuberance breaks away from die.

Further technical scheme is:

Described drift pours the interior degree of depth s of rapidoprint for the first time and the thickness t of rapidoprint meets 0.5t＜s≤0.75t.

The characteristics of the inventive method are aperture is implemented twice or stamping-out repeatedly, can make punch crooked and not the maximum length during unstability increase, that is indirectly reduced the conventional hole dimension limit of rushing aperture, also be that the aperture of punching same size can adopt the punch of small cross sections and is not easy to fracture.

The present invention relatively is suitable for realizing at multistation progressive die from technical process, i.e. stepping, location, stamping-out aperture repeatedly.But by suitable positioner, the present invention is fit to be applied on other cold-punching mold equally.

Further specify technical scheme of the present invention below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the type schematic diagram of aperture.

Fig. 2, Fig. 3 are respectively the punch schematic diagrames of existing method punching small holes.

Fig. 4 is the multi-station progressive die schematic diagram.

Fig. 5-Fig. 8 is the principle schematic of the inventive method punching small holes.

Blanking pressure when Fig. 9 is stamping-out---punch travel curve map.

Specific embodiments

Multi-station progressive die as shown in Figure 4, comprise first, second drift 1,1 ', material pressing device 5 and respectively with drift 1,1 ' and material pressing device 5 corresponding lower bolsters 4 of establishing die 401 and not establishing die, have rejected material chamber 402 with the die 401 of the second drift 1 ' corresponding.

When multi-station progressive die stamping-out aperture, rapidoprint 3 carries out according to the following steps along lower bolster 4 grading processes:

The first step, as shown in Figure 5, the first drift 1 pours and is positioned at that thickness is the rapidoprint 3 of t on the lower bolster 4, the degree of depth s of drift makes rapidoprint 3 form top recess 301 and following protuberance 302, and guarantee 0.5t＜s≤0.75t, namely the aperture waste material (protuberance) of required excision is carried out die-cutly, but will not cut off fully, the aperture waste material (protuberance) of required excision not exclusively separates with rapidoprint 3 parents, withdraws from drift 1;

As shown in Figure 6, rapidoprint 3 when grading along lower bolster 4 by spring knock pin 6 jack-up, so that it sends next station to smoothly in the situation that protuberance 302 breaks away from dies 401;

Second step, as shown in Figure 7, smooth part a without die 401 cutting edges pushes back following protuberance 302 in the rapidoprint 3 by material pressing device (stripper) 5 and lower bolster 4, namely counter the returning of part aperture waste material that does not have in the first step to separate fully with parent, on the surface, becoming again a smooth rapidoprint, is that the 3rd punching prepared;

The 3rd step, as shown in Figure 8, the second drift 1 ' again pour is on the rapidoprint 3 in 301 positions of the recess in the first step, implement punching, protuberance 302 washed out fall in the rejected material chamber 402, form aperture at rapidoprint 3, namely go out the part aperture waste material that separates fully with parent, reach product requirement;

For the need situation of stamping-out aperture repeatedly, can realize by carrying out again the operation of the 3rd step after repeating first and second step;

Principle of the present invention:

Because the destruction trend of aperture blanking punch belongs to the strut buckling problem, according to the strut buckling stress formula, the compression calculation formulas is:

$F_{\min }\≥\frac{F_p}{\left[\mathrm{\σ}\right]}$

In the formula:

F _p---the vertical gross pressure of punch (N);

F _Min---punch minimum cross section area (mm ²);

The permissible compression stress (MPa) of [σ]---punch material;

According to above-mentioned formula as can be known, punch bears compression and the minimum cross section area of unlikely destruction, is inversely proportional to the permissible compression stress of punch material, is directly proportional with the vertical gross pressure of punch.

For the punch without guider, its bending resistance can be carried out verification with following formula:

Have for round punch:

$I_{\max }\≤\frac{{30d}^2}{\sqrt{F_p}}$

Have for non-circular punch:

$I_{\max }\≤135\sqrt{1/F_p}$

I is the moment of inertia (mm of punch smallest cross-sectional in the formula ⁴), F _pBe the blanking pressure (N) of punch, d is the minimum diameter (mm) of punch.

By above two formulas as can be known, a crooked and maximum length mistake during unstability not of punch! Do not find Reference source., become positive correlation with the punch sectional dimension, become the inverse correlation relation with the size of blanking pressure.

From the above analysis, in order to prevent producing the strut buckling problem when the stamping-out aperture, can address from two aspects, first aspect increases the punch sectional dimension, improves the moment of inertia in cross section; Second aspect reduces blanking pressure.

The expression formula of aperture stamping-out blanking pressure is: P=σ tT, and in the formula, P is blanking pressure, and T is the stamping-out area circumference, and t is material thickness.σ is the shearing strength of material.For need to be on certain material the aperture of the required fixed size of flushing technology, reduce blanking pressure, only reduce material thickness t.

In the actual production practice, the thickness t of stamping-out material can not change according to the product requirement regulation.In order to reach the purpose that reduces material thickness t, only on the Sheet Metal Forming Technology method, improved, the thickness t of same stamping-out material is divided into twice or repeatedly carries out stamping-out, then the thickness of stamping-out has just become 1/2t or 1/n t each time, and corresponding blanking pressure also just is reduced to 1/2P or 1/n P.

Of the present invention by reducing blanking pressure, thus conventional method of rushing the hole dimension limiting value of aperture reduced, and blanking pressure during available stamping-out---punch travel curve makes an explanation and illustrates from the material deformation theory.

Blanking pressure when Fig. 9 is stamping-out---punch travel curve, among Fig. 9, the AB section is equivalent to the strain stage of stamping-out, and behind the punch contact material, load sharply rises.Clamp-on material when the punch cutting edge, namely enter plastic period after, the rate of climb of load just slows down, shown in BC section among Fig. 9.Although because punch is clamp-oned material the material area of bearing blanking pressure is reduced, but as long as the impact of materials processing sclerosis surpasses the impact that shear(ing) area reduces, blanking pressure will continue to rise, when both impact reaches equal moment, blanking pressure reaches maximum, i.e. the point of C among the figure.After this, the impact that shear(ing) area reduces has surpassed the impact of materials processing sclerosis, and blanking pressure descends, and punch continues to press down, and the micro-crack of material internal is expanded rapidly, shows to have formed on the product to cut off line.Blanking pressure sharply descends, and shown in figure CD section, at this moment, is the fracture stage of stamping-out.

Therefore, as long as the one-tenth-value thickness 1/10 (punch travel) that for the first time drift enters material during stamping-out is higher than the B point, be lower than the C point, just can reduce the size of the blanking pressure first time.And for the second time during stamping-out, because by behind the stamping-out for the first time, material has had plastic deformation, and formed and cut off line, naturally also reduced the size of its blanking pressure.If carry out repeatedly stamping-out, then its each time further reduction of size of blanking pressure, but the one-tenth-value thickness 1/10 (punch travel) that drift enters material when it should be noted that stamping-out each time should be higher than the corresponding blanking pressure of corresponding material---the B point of punch travel curve also is lower than the C point.

Claims (2)

1. the process of a multistation progressive die stamping-out aperture, it is characterized in that comprising drift, material pressing device and correspondingly with drift and material pressing device respectively establishing die and do not establish in the multi-station progressive die of lower bolster of die, carry out according to the following steps when rapidoprint is grading along lower bolster:

The first step, the first drift pour in the rapidoprint that thickness is t, and the degree of depth s of drift makes rapidoprint form top recess and following protuberance, withdraws from drift;

Second step, material pressing device and lower bolster push back protuberance in the rapidoprint;

In the 3rd step, the second drift pours on the rapidoprint in the recess location in the first step again, and protuberance is washed out the formation aperture;

Perhaps repeat as required to carry out for the 3rd step again after first and second step;

Rapidoprint when grading along lower bolster by elastomeric element jack-up, so that it sends next station to smoothly in the situation that protuberance breaks away from die.

2. the process of described multistation progressive die stamping-out aperture according to claim 1 is characterized in that described drift pours degree of depth s in the rapidoprint for the first time and the thickness t of rapidoprint meets 0.5t＜s≤0.75t.

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