Arrangement technology of hardware stamping continuous mold

In the production of hardware, home appliances and daily industrial products, as one of the leading processes, the huge potential for energy saving and consumption reduction needs to be explored.


Among them, there is a lot of room and potential to save raw materials. According to research in the national electrical switches, agricultural machinery, home appliances and instrument industries in recent years, the utilization rate of stamping plate materials is roughly between 62.5% and 73.5%.


With the increasing market competition, the selling price of raw materials has risen sharply with the rising energy prices. Saving raw materials has become an urgent energy-saving and consumption-reducing task in stamping processing. It is an effective way for related enterprises to reduce costs and increase benefits, and an important means to enhance the market competitiveness of products.


It can be seen from Table 1 that in batches and mass production, if the stamping material utilization rate η is increased by 1%, the punching cost will decrease by 0.4 to 0.5 percentage points.

Principles for layout and continuous stamping. Before blanking of flat plate punching parts (including the unfolded flat blanks of various forming punching parts - the same below) is carried out, in order to save materials, the plates, strips, belts and coils are arranged economically and reasonably to obtain the best arrangement and achieve the highest material utilization rate possible. In cold stamping process design and die design, this is an important and highly technical task; in cold stamping structure design, stamping part drawings, stamping processes and their arrangement drawings are the main basis.

In known professional publications, hedging parts blanking, namely single-station punching die and composite die punching, have never been involved in the arrangement of multi-station continuous die punching.

The arrangement diagram of multi-station continuous stamping parts should fully represent the stamping process and the sequence of stamping steps, mark the specific data of feeding distance, edges and edges, as well as the feeding method between stations, and all stamping processes and deformation and separation processes of stamping parts.

The layout diagram is closely related to the selection of molds, structural design, stamping material utilization rate η, stamping productivity and stamping production cost, and also affects the quality of stamping parts and mold life.

When arranging, we must fully consider the material supply conditions and the production conditions of stamping equipment. On the basis of ensuring the quality of the punching parts, we must strive to have a better structure, better operating safety and mold making process. We must comprehensively and comprehensively analyze various factors affecting the arrangement, conduct multiple solutions to select the best from them and determine the best arrangement.

Before the die design begins, we must analyze the punching drawings and layout drawings to understand its main technical requirements and stamping processing difficulties, and compare the layout drawings to verify the rationality of the stamping process and possible problems in order to lay the foundation for the die structure design.

Among the many single-process punches, only blanking dies and single-station composite die punches need to be arranged and designed. That is, when the punching (blanking) flat stamping and forming stamping parts are unfolded, the sampling is required.

Moreover, most of them are conventional sampling methods for scrapping with edges and side edges. Sometimes one or two unblocked sampling may occur, and most of them can only achieve less scrap. No matter what sorting method is used, the rationality and advantages and disadvantages of the sorting are generally measured by the utilization rate of the material.

The arrangement of continuous die punches is different from the above. Material utilization η is not the most important and only criterion for measuring the quality of the sorting.

When sorting continuous die punches, the first thing to do is to analyze the hedge part process, reasonably design the stamping process and stamping process step sequence, fully consider the characteristics of the continuous stamping process and the needs of the die structure design, pay attention to the selection of feeding methods between feeding and stations and the design of the positioning system.

Therefore, the arrangement of continuous die punches is based on the continuous stamping process step design, with the core of ensuring the quality of stamping parts, its dimensions and shape accuracy, the order arrangement of stamping steps and the selection of feeding between stations as the guide, and the purpose of die selection and structural design, the basic principles that should be followed are as follows: (1) It is conducive to the selection of simpler die types and structures, which are safe in operation and good punching quality. (2) The mold has good manufacturing process, easy grinding, short mold making cycles, and low mold making and mold making costs.

(3) The board utilization rate is high. (4) The mold life is higher. (5) Stamping efficiency is higher and stamping parts production cost is lower. Of the above five articles, Article (1) is the primary priority.

Sometimes it is impossible to have both. The user requirements and delivery time should be considered first, and other terms can be appropriately relaxed. In many cases, higher material utilization η often complicates the structure of the die, making the mold more difficult, and even existing molding equipment and technical level are difficult to manufacture. No matter how good the sampling is arranged and how high the value of η is, it must be given up; some would rather reduce the board utilization η to obtain better molding processability, shorter molding cycle, and higher mold life.

The selection of arrangement form and its relationship with die type and structure For blanking dies and composite dies with only one station, the arrangement methods for flat plate blanking punches and various forming punches to spread flat blanks on plates, strips, belts, and coils are usually: single row inline, single row incline, double row incline, double row incline, double row incline, double row incline, double row incline, multi-row incline, parametric row incline, mixed row incline, etc.

Different arrangement methods to obtain different material utilization rates. For different arrangement methods, the first thing to consider is to meet the dimensions and shape accuracy required by the punching parts, and then decide to choose the appropriate die type and structure.

If the dimensional accuracy of the punching parts is required to be above 1t10, the sampling method should be adopted with edges and sideways; the dimensional accuracy of the punching parts without edgeways is poor, generally below 1t12, or even as low as 1t14. If the dimensional accuracy of the punching part is as high as 1t9 or above and the punching part is required to be straight, a die with a sliding guide column die frame with a pressurized unloading plate structure should be selected, and the arrangement should be given enough edges and edges.

According to the German industrial standard din1543, cold stamped steel plates are classified according to thickness t: t＜3mm is a thin plate.

In the production of instrumentation and electronics industry products, ultra-thin foil stamping parts with t≤0.3~0.1mm or even ≤0.1~0.05mm are often used, which brings many difficulties to stamping sampling and die design.

Because the layout edge, lap width and punching gap size all increase or decrease with the punching material thickness t.

When t≤0.5mm, the width of the overlap and edge must be greater than t so that it will not be pulled into the die hole during punching, and it must have sufficient strength and ensure that the overlap frame has good feeding stiffness; for low carbon steel plates with t=0.3mm, according to gb/t 16743-1997 "Blanking Clearance" Internationally stipulated Class I clearance, 3%t can be taken as the single-side clearance of the die, c=3%×0.3mm=0.009mm, if t=0.1mm, then c=0.003mm, that is, 3μm.

The matching clearance of the guide post and guide bushing specified in gb/t2854-90 international grade I sliding guide guide post formwork is 0.010~0.016mm. Therefore, when punching and continuously stamping the above-mentioned ultra-thin materials, special attention should be paid to selecting the appropriate layout method and designing a reasonable and precise mold structure. Otherwise, it will be difficult to complete the punching of this type of punching parts, and it will be impossible to achieve the required size and shape accuracy.

For the continuous stamping and forming of ultra-thin stamping parts with t<0.5mm, the layout overlap and edge can be of the same width, and can be appropriately enlarged depending on the needs of the die structure design. In terms of the selection of the die structure type, it is recommended to choose the guide post mold frame elastic pressure discharge guide plate type punch, and it is best to install the elastic pressure guide plate on the guide pillar and install a small guide post on the discharge plate (guide plate).

In order to ensure that the elastic discharge guide plate type punch has precise guidance and improves the punching accuracy of the punching die; the coaxiality and positioning of the punched parts group holes put forward higher requirements for the layout distance accuracy and punch feed positioning. Special attention should be paid when laying out samples.

For ultra-thin punched parts with material thickness t ≤ 0.1mm, especially complex-shaped punched parts formed by multiple stations and one mold, it is not suitable to use multiple rows of diagonal rows, opposite rows and turning over, and it is not suitable to use mixed rows.

Otherwise, the lap frame will be easily deformed, broken, or even pulled into the die during feeding, which will affect production, increase waste and defective products, and damage the mold. For medium-thick plate stamping parts with a material thickness t≥3mm, it is not recommended to use lap edge layout. For stamping parts t≥4.75mm, it is not recommended to use nesting and patchwork layout. Otherwise, it will bring difficulties to the structural design of the mold.

For high-precision foil stamping parts with dimensional accuracy ≤±0.01mm and material thickness t≤0.1mm, especially stamping parts with complex shapes whose accuracy is higher than 1t9 level, it is recommended to use the ball guide post die frame elastic discharge guide plate die structure.

Key points of layout design The layout design of single-station blanking molds and composite dies is to unfold the shape of the flat blank according to the flat blanking parts and three-dimensional formed parts, and repeatedly arrange it on the strips and strips. While ensuring the quality of the punched parts and the production efficiency required by the process, the die structure is simpler.

Mold making is more convenient, the highest possible material utilization rate is achieved, and a better layout method is selected. Generally speaking, the shape and size structure of the blanking parts determine the type of layout. Most of them use the traditional layout method with edge and overlapping edges to perform blanking with waste materials.

Based on many years of practical experience, the layout design of stamping parts for single-process blanking and composite blanking, as well as single-station comprehensive composite stamping, can be considered based on the one-time blanking of flat blanks for flat blanks and three-dimensional formed parts. The layout of continuous die stamping parts is much more complicated than that of a single punch die. The layout must ensure the smooth implementation of the continuous stamping process and obtain the highest possible eta value, safe operation, high efficiency, many influencing factors, and high requirements. The steps and key points are as follows:

(1) After detailed process analysis of stamping parts, study the feasibility of continuous stamping and molding of stamping parts and propose multiple stamping process plans for comparison, and select the best among them to implement layout.

(2) The shape, size and accuracy of stamping parts directly affect the continuous stamping process and the sequence of work steps. When laying out, the processability of continuous stamping and the needs of die structure design must be considered. Pay attention to the following points in the sequence of work steps and work station arrangement:

a. Among the holes on the punched parts, holes that require a hole spacing accuracy of 1t10 or above or a hole spacing tolerance value less than 0.01mm should be punched out at one or two adjacent stations;

b. The hole wall and edge of the punched part are smaller than the material thickness t or less than 2mm. They should be punched out at two stations in steps to enhance the strength of the die and expand the installation position of the punch on its fixed plate;

c. For the coaxiality and positioning of group holes, the requirements are very high, and the tolerance is less than 0.01mm. The relevant holes can be punched out at one time or at two adjacent stations. The parts that require smooth punching and blanking should be concentrated on one or two stations;

d. If the shape of the punched parts and the expanded roughness of the formed parts have very strict tolerances, consider overall blanking and then bending or drawing; if the local boss or notch size of the punched parts is strict, it can be punched separately at multiple stations and then assembled together;

e. For small, complex-shaped stamping parts with large output, multi-station continuous stamping with one die should be used as much as possible to improve the quality and efficiency of the stamping parts;

f. For high-precision stamping parts with dimensional accuracy requirements of 1t10 or above, work steps should be minimized during layout to prevent too many stations, large accumulation errors in feeding, and reduction of stamping accuracy. Special stations should be arranged for local fine blanking, upsetting, flattening, etc.;

h. For stamping parts with complex multi-directional bending, lateral punching and incisions that require transverse force stamping, consideration should be given to using wedge-driven transverse stamping with one die after plane punching, incision or before blanking to improve accuracy and efficiency.

(3) Considering the needs of the die structure design and the requirements for the position required for stamping deformation, set up necessary neutral stations and increase the installation position of the punch on the fixed plate; if the material is flattened and thinned to increase the covered die surface area, empty stations should also be added to increase the wall thickness of the die.

Layout types and methods of continuous die stamping parts

According to the characteristics of the continuous die stamping process, the station and feeding method, the presence or absence of overlapping edges in the layout, and the method of removing process waste, the layout of continuous die stamping parts can be summarized into the following types and arrangements:

Cutting combination layout

Each station punches and forms a part of the punched parts respectively. Each station is relatively independent and has nothing to do with each other. Its relative position is controlled by the mold, and is finally combined into a complete and qualified punched part, see Figure 1a), b), f), j).

Cutting combination layout

The inner hole and shape of the punched parts, or even a complete punching line of any shape, are punched separately at several stations, and finally assembled into a complete punched part. Although it is similar to the slitting combination, it is not the same. The cutting and cutting combinations of each station and the punching edges are related to each other, and the interface parts must overlap, which increases the difficulty of mold making, see Figure 1c), d), and e).

Cutting edge layout

Use the edge cutting method to obtain the complex shape of the side of the punched part, that is, cutting edge layout. When the length l of the punching edge in the feeding direction is equal to the advance distance s, that is, l=s, then the punch can replace the side blade and assume the task of cutting the edge and setting the distance of the fed raw material.

This type of side punch is commonly called a forming side edge. Due to the small variety of jb/t-76481-94 standard side blades and limited size specifications, the maximum cutting edge length is only 40.2mm. When the feeding distance s>40.2mm, only non-standard side blades can be used.

Another disadvantage of using a standard side blade is that it requires cutting a certain width of material from the side of the raw material to form an incision with a length equal to the feeding distance, and positioning the feeding raw material, which increases process waste and reduces the eta value by 2% to 3%. Using the side punch to cut the edge can not only complete the punching of any complex shape of the side profile of the stamping part, but also realize the distance limit of the feed raw material, replacing the standard side blade, killing multiple birds with one stone, see Figure 2a), b), c).

Trimming and patterning

For slender thin material punching parts, long punching parts with complex outlines to be punched are connected to the overlapping edge. Using cutting overlapping edge layout can achieve high-quality and high-yield results, and can avoid shortcomings such as distortion and deformation of slender punching parts and difficulty in unloading.

Typical stamping parts are instrument hands, watch second hands, etc. The above-mentioned cutting and overlapping patterning is very effective. For the convenience of mold making, the overlapping edge is sometimes enlarged to facilitate blanking, and the punched parts left on the raw material as the overlapping edge are finally cut and separated, see Figure 2e), j), h).

Nesting and layout

Use the structural waste of the inner hole of the large-size punched parts to punch smaller-sized punched parts of the same material at a dedicated station in the same set of continuous dies, that is, nesting and layout.

Generally, the small-sized punched parts in the inner hole are punched first, and the large-sized punched parts are often punched out at the last station.

Nesting gaskets using a single-station composite punching die is a well-known typical nesting pattern. For nesting and layout of multi-station continuous punching parts, since there is no overlapping nesting at the upper and lower stations, the coaxiality is required to be high, and the feeding distance must be small to ensure the size and shape accuracy of the nesting and punching parts, see Figure 4c) and d).

Piecing and layout

The process waste of stamping parts and the structural waste connected along the edges are combined to punch multiple stamping parts of the same material, that is, patchwork layout.

The difference from nesting is that patchwork uses process waste or redundant edges and overlaps as much as possible, as well as outer edge structural waste due to the complex shape of the stamping parts and the large difference between convex and concave, to punch multiple stamping parts with the same material. When laying out, make full use of the convex and concave parts of the stamping parts, intermix and embed them into a combined arrangement, so that the raw materials can be fully utilized. See Figure 4a) and b) for details.

Layout without overlap and blanking without waste material. Since most of the continuous die punching parts are laid out with edge or overlap, only waste blanking can be done. If the layout can be carried out without edges and overlapping edges, and at the same time, there is no structural waste produced in the punched parts, then waste-free blanking can be carried out.

It is rare to have completely waste-free punching parts that can achieve a plate utilization rate of 100% or close to 100%. Any punched parts that can be laid out without overlapping can be punched with less waste. See Figure 5.

To implement no-waste and less-waste punching of blanking parts, you must first lay out the blanking parts without overlapping edges, as shown in Figure 5.

Because the implementation of edge-free layout requires certain conditions and methods. In addition to the above-mentioned continuous punching parts that can be laid out without overlap and punched with no waste or less waste, single-process punching dies and single-station composite punching dies can also do the same.

Continuous composite die stamping parts layout with non-linear feeding

The feeding direction of most continuous molds is on the same plane along a straight line, and the feeding of each station is carried out by feeding in raw materials. For this reason, the punched parts connected by overlapping edges are always retained on the raw materials for stamping processing at each station.

It is not until the last station of processing that the finished punched parts connected to the overlapping edge can be separated from the raw materials. For some stamping parts with large bending height, large drawing height and complex shapes that require multi-directional force bending, it is often necessary to blank the entire material and then form it on another set of dies.

Otherwise, a large opening height of the die is required to remove the punched parts from the die cavity. If a conventional continuous die is used to arrange the workstations in a straight line on the same plane along the feeding direction, it will be difficult to design the die structure.

This kind of stamping parts are formed in one mold with a multi-station continuous die. The layout method is completely different from the conventional continuous die layout mentioned above. After the flat blank is unfolded by overall blanking, a special pushing mechanism driven by an inclined wedge is used to push the blank to a forming station at a certain angle with the feeding direction of the raw material, and bend or draw it into shape. Make the various workstations of the die to be arranged in an L shape, and each workstation is not on the same plane, see Figure 6 and Figure 7 for examples.

With the rapid development of modern stamping technology, the continuous improvement of stamping mechanization and automation, and the improvement of stamping safety production requirements, continuous dies with this type of structure will be increasingly used widely.


Figure 6 shows a three-station continuous composite mold for lifting ring stamping parts. The first station punches rectangular holes, and the second station is blanking and bending compound stamping. The third station is a feeding system driven by a wedge 8. After the bent workpiece at the second station is pushed into position along the core bend 12 through the push plate 6, two sets of 13 wedge transmission mechanisms are used to apply force relative and perpendicularly to the feeding direction to push a pair of forming female mold parts 17, and the stamping workpiece is finally formed.


This punching die has both the action characteristics of a continuous die and the functions of a composite die. Since the second to third stations are where the workpiece is separated from the raw material and formed separately, it is unrealistic to call it a progressive die. Calling it a continuous die ignores the function of the composite stamping of the second station and the characteristics of the separation and deformation of the entire die. Therefore, it is more appropriate to name it a continuous composite mold.

The continuous composite mold in Figure 7 adopts staggered double-row in-line arrangement. After the overall blanking, the unfolded blank is pushed to both sides and bent into shape at the third station. The production efficiency is high and the quality of the punched parts is good. This type of automatic or semi-automatic continuous composite mold is safe to operate and will be used more and more as the types and specifications of coil materials are diversified.

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