Silicone mold-molar stick silicone mold
Multi-station progressive die manufacturing process
This article introduces the design process of progressive die layout, inserts, templates and other parts, points out the points that should be paid attention to in progressive die design, and introduces some common faults and solutions in mold production.
For stamping production, the single-station mold structure is single, the production efficiency is low, and the sheet metal parts cannot be too complicated, otherwise it will require multiple single-station molds to achieve. If a progressive die is used for stamping production, these shortcomings can be changed. The progressive die is characterized by high production efficiency, short production cycle, and few operators, which is very suitable for mass production.
2 Key Points of Progressive Die Design
2.1 The unfolding calculation and layout of the product
After reading the product drawing, you must first carry out the unfolding calculation. The unfolded size of the product is generally obtained through empirical formulas, and some are calculated through software. No matter which method is used, you should ensure that the calculation result is within the allowable range. Because once the unfolded size calculation is wrong, the final product must be unqualified, and it will be very troublesome to correct it. Therefore, the results of the expansion calculation should be checked to ensure that the expansion size is accurate.
The process of designing the layout drawing is the process of determining the mold structure. If the layout drawing is determined, the basic structure of the mold is also determined. Therefore, in the layout design, detailed consideration must be given to the overall situation, not limited to the local structure, and more attention must be paid to the details. For example: when allocating each step of the station, not only need to consider which station is punched, which station is bent, which station is formed, but also how each insert should be arranged, and whether the arrangement space is enough , Is there any mutual influence between the various inserts? For the punching station, the main consideration should be how to distribute the punching force evenly and reasonably, whether the strength of the punching die can be guaranteed, and the complicated punching should be properly decomposed. For stations such as bending and forming, you should consider whether it can be formed at one time. If you are not sure, you should add a pre-forming or empty step to facilitate mold adjustment. For products that require high flatness or are prone to warping during forming, a leveling station should be added to ensure flatness.
When arranging the station sequence, it should be noted that the front and rear stations should not be affected, otherwise the order of the stations should be adjusted. For example: when performing zigzag bending, if there are punching holes on the zigzag curved surface and the punching position has strict tolerance requirements, then zigzag bending should be performed first, and then punching, so as to ensure the punching position.
The last station of the progressive die is a very important station, because it relates to how the product is taken out of the mold. The general delivery methods mainly include blowing out and dropping, and some special products also need robots to pick up the parts. Either way, it needs to be cut. The size and position of the cut should be carefully considered, because they not only affect the output of the mold, but also affect whether the strip can be fed in stably and smoothly. However, if the blanking method is used, the direction of the burr at the cut is opposite to other positions, which can only be determined after discussing with the product designer.
When designing the layout, under the premise of ensuring the smooth feeding of the strip and stable production, the width and step distance of the material should be reduced as much as possible to reduce the cost of sheet metal parts.
2.2 Insert design
(1) Punching punches.
The shape of the punching punch is determined by the shape of the product. It can adopt a straight structure or a reinforced structure. The main fixing methods are: hanging table fixing, pin fixing, screw fixing, pressing block fixing, top wire fixing. Among them, the hanging platform is the safest and most reliable, and the pin fixing is not commonly used. The other three fixing methods are mainly convenient for quick replacement during maintenance. You can freely choose according to your needs.
(2) Die inserts.
The cutting edge of the die can be cut directly on the die plate, but for products with larger output or higher hardness, die inserts should be designed to facilitate maintenance. The fixing methods of the concave mold insert include: hanging table fixing, screw fixing, and pressing block fixing.
When designing a single-side blanking die insert, in order to prevent the waste from floating up, a sharp corner of the squeezing material should be added on the side that is not blanked to squeeze the waste and prevent it from floating, as shown in Figure 1.
(3) Bending inserts.
The bending inserts can be fixed with a hanging table or with screws. The gap between the bending convex and concave dies should be one material thickness. The head of the bending punch should be designed with an arc R angle to avoid scratching the product during bending (as shown in Figure 2). For the bending die with right-angle bending near the bending line, a correction rib (as shown in Figure 3) should be designed to cause plastic deformation at the root of the product during bending, reduce springback, and ensure a 90O bending angle.
2.3 Template design
The standard progressive die template includes: discharge plate, fixed plate, concave template, upper die seat, and lower die seat.
Among them, the unloading plate, the fixed plate, and the concave template are the key three templates, which are also indispensable for the progressive die.
The fixed plate plays the role of fixing the convex mold; the discharge plate mainly plays the three functions of discharging, guiding and pressing; the concave template can not only serve as the cutting edge of the concave mold, but also can inlay the concave mold insert on it.
4 small guide posts are used to guide between the 3 templates. The 4 small guide posts are fixed on the fixed plate of the punch, and 4 small guide sleeves are respectively set on the discharge plate and the concave template to accurately control the small guide posts and The matching accuracy between the small guide bushes is to ensure the movement accuracy of the punch.
In the design of the progressive die, one item is also very important, that is, the design gives way. Generally, all subsequent stations of the bending or forming station need to give way, and to give way fully, not only should the static give way, but also Consider whether dynamics need to give way.
2.4 Other parts design
In the progressive die, some auxiliary parts also play an important role in the smooth work of the die.
(1) Guide nails. In the progressive die, the guide pin has a greater impact on the accuracy of the product. Generally, two holes are punched in the first station, and the subsequent stations use these two holes for double guidance, which can better guarantee the product Accuracy. When designing the guide nail, pay attention to controlling the length of the guide nail. When the mold is in a free state, the length of the straight arm of the guide nail extending out of the discharge plate should be less than one material thickness of the product, which can effectively avoid stripping phenomenon.
(2) Floating feeding nails. The feeding height of the strip is determined by the floating feeding nail. When designing the feeding height, it should be ensured that the strip will not be hindered by any inserts or ejector rods when it is fed at this height. The floating feeding nail can not only lift the strip, but also guide the strip. Its number and position should be determined accordingly according to the width and thickness of the strip.
(3) Lift the material block and the ejector rod. When the strip is subjected to forming processes such as bending, cutting, and stretching, a packing force will be generated to make the forming part of the strip tightly wrapped on the insert, and it is not easy to demold. In order to ensure that the strips bounce up smoothly, a lifting block or ejector rod should be designed at an appropriate position, and the strips should be ejected by spring force. In the last station, the cut products sometimes adhere to the mold due to the effect of the punching oil, so the upper and lower molds in the last station should be designed with ejector rods to prevent the phenomenon of overlapping parts and damage the mold.
In addition, in order to prevent the misfeeding and the floating of waste from damaging the mold, an induction alarm device for misfeeding and the floating of waste can be designed.