Improved design of composite upper die structure for bucket top
In the production of 200 liter steel drum, the design of punching, flanging and forming composite mold structure at the top of the bucket is reasonable, which not only affects the punching, flanging and forming quality of the two tops of the bucket, but also directly affects the production efficiency. .
To ensure that the two holes on the top of the 200-liter steel drum are punched, flanged, and the wall of the formed cylinder is vertical, or that the hole and the hole after the forming of the flange are tightly required to have a dimensional difference and a shape difference. It is not only necessary to correctly and reasonably determine the diameter of the pre-punching hole and the shape and size of the convex and concave molds and the mutual matching gap between them, but also to consider the easy positioning and unloading of the mold, so that the overall structural design of the composite mold is more compact and reasonable. . In this way, not only can the reliability of punching, flanging, forming and positioning of the two ports be ensured, but also the operator can operate with ease, thereby improving production efficiency.
First, the mold structure analysis
Originally, our factory purchased two sets of top punching and burring forming composite dies without a rigid unloading device from a barrel mouth factory, and used it with the corresponding lock dies. One set is used for punching, flanging, forming and locking of the injection port on the barrel item; the other set is used for punching, flanging, forming and locking of the venting opening on the top of the barrel. The structural principle of the upper mold is basically the same, as shown in Figure 1. Because the purchase of the lower die is not necessary to make a large structural improvement compared with the conventional punching, flanging, and forming die, this paper does not discuss the structure of the lower die. When using the improved upper die and the matching shown in Figure l When the lower mold and the lock mold were used, the pressure was tested on the self-made barrel top two pressure test device, and a certain leak phenomenon was found, and the quality was very unstable. Moreover, the level of leakage rate has a great relationship with the operation method of the lock operator. It is proved that different operators have different leakage rates. When the locking operation method is not correct, the leakage reaches about 30%, which seriously affects the normal production of the 200-liter steel drum.
Figure 1 Composite upper mold structure before improvement
Later, our factory redesigned two sets of barrel top punching and forming composite upper die with rigid unloading device. It is also used for punching, flanging and forming of the injection port and the vent opening on the top of the barrel. The basic principle is the same, but the structure of the upper mold has been greatly improved. :as shown in picture 2. The upper mold can meet the specified requirements after one-time debugging in the use process of the corresponding lower mold and the lock mold. After the lock was installed, it was never found that the steel drum produced any leakage at the two mouths during the pressure test, and the quality was always stable. It will not cause leakage due to different operators and methods when locking, and the quality is relatively stable, which can always ensure the normal production of 200 liter steel drum.
Figure 2 Improved composite upper mold structure
Compared with the two structures before and after the improvement of the mold, the maximum feature of the improved mold adds a complete set of rigid unloading devices, which can play a smooth hard unloading function. With the setting of the structure of the mold unloading function, the foundation of the reasonable clearance of the convex and concave molds is laid, which creates favorable conditions for the improvement of the main functions of the whole set of molds including the lock mold. Once the improved design is implemented, the improved mold design is more reasonable; the function is more reliable, comprehensive and perfect.
Second, the composition, movement and adjustment of the unloading device
The hard unloading device for the top of the barrel and the hole forming the composite mold is improved on the basis of the original composite mold. As shown in Figure 2a. Mainly composed of the unloading sleeve 11, the movable coupling pin 10, the return spring 4, the unloading link 3, the fastening screw 2, the return spring regulating nut 1 and the like. The movement process of the top piece is: when the mold is adjusted and the punching machine is turned on, when the slider is at the top dead center position, the adjustment of the screw can be adjusted through the unloading part of the punching bed, so that the unloading device is in the unloading state (even When the end surface of the unloading sleeve is flush with the lower end surface of the inner diameter hole of the flanged die, the top of the bucket is placed between the upper and lower molds, and the pedal is stepped to make the punch slide down a certain distance, resetting The spring 4 resets the unloading device (in the non-discharged state) due to the loss of the unidirectional axial external pressure and there is no statement that the operator can easily feel. As the sliding continues downward, the punching, flanging, forming and resetting actions of the top of the bucket can be completed to make the sliding back to the top dead center instantaneously, and the return spring regulating nut 1 and the punching bed in the unloading device can be completed. The provided top mold beam and the unloading sleeve 11 are interlocked with each other to directly discharge the bucket top workpiece from the rigid top of the concave mold. Thereby completing a complete unloading process.
The adjustment of the unloading device generally has two aspects: on the one hand, the adjustment of the return spring pressure regulating nut 1 and the fastening of the fastening screw 2 during the assembly of the mold. The purpose of adjustment and fastening is to ensure that the device can be flexibly and flexibly reset when the return spring strongly overcomes the self-recombination force between the device and the die beam. On the other hand, the mold is placed on a punching machine for general mold adjustment. In the trial process, a special unloading adjustment is made. The purpose of the adjustment is to ensure the realization of the rigid unloading device when the unloading device is in the unloading state.
The above description is the composition, movement and adjustment of the composite upper die unloading device on the top of the bucket. The composition, movement and adjustment of the venting composite upper die unloading device, the design principle and adjustment of the composite upper die are basically similar, only the structure is different. As shown in Figure 2b. Therefore, when discussing the compound on the composite, this model is generally not involved, but all the characteristics and debugging methods of the composite mode will be able to get the same meaning from the discussion in Figure 2a.
Third, the basis for mold improvement
Since the basic constitutional principle of the flanging die is analyzed, the stress state at the time of flanging is biaxially stretched, and the stress in the material thickness direction is considered to be approximately zero. When the cuff gap is properly reduced, at the end of the cuff forming process, the outer ring of the material to be turned over can be folded like a rigid steel ring. Thereby limiting the generation of cracks while at the same time easily obtaining the desired flanging shape and size. At this time, the material which is formed by the flange forming is subjected to a large compressive stress in the direction of the material thickness, and it is apparent that the transformation of the stress state will improve the plasticity of the material. According to this theory, and through the practice of countless people, it is verified that the best value of the edging between the convex and concave dies is 0.85 times the thickness of the tumbling material: the best edging punch is excessively rounded The radius is 4 times the thickness of the material being turned. It is conceivable that in the mold design, if the participation of the hard unloading device is not considered, it is difficult to achieve the general automatic unloading action when the above two requirements are met. If the empirical values â€‹â€‹of the above two items are not used, then the effect of the forming of the flanging is inevitably poor.
According to the above-mentioned design of the flanging die design, when designing the punching and flanging forming composite die of the 200-liter steel drum top, it is necessary to solve the main problem of the unloading part, and it is easy to realize the punching, flanging, forming and unloading of the die. The composite coordination function of the pieces. Otherwise, in the process of using a mold designed according to the formal theory, the workpiece is not contained in the upper concave mold, or the sleeve is clamped on the lower convex mold. From the observation of the production site, it is known that there are many cases contained in the upper die. It is difficult to quickly remove the workpiece from the mold, and it is laborious to unload the workpiece with a rubber hammer, which seriously affects the improvement of production efficiency. However, the unloading of the lower mold can be designed to achieve a satisfactory solution by designing a rubber rubber ring on the convex and concave mold. This rubber ring not only can take the role of the unloading part, but also can take the role of leveling. The unloading problem of the upper mold must be designed as the hard unloading device shown in Fig. 2a, so that the unloading is more guaranteed. Therefore, the improved design and production of the top composite mold structure is the main function of the mold and reliable performance. way.
Fourth, the main purpose of mold improvement
The main purpose of mold improvement is to ensure reliable sealing performance after the screw lock is installed, thereby improving product quality. Because the difference in size between the outer diameter of the coil and the inner diameter of the top flange of the barrel is ensured by the rational design of two sets of flanged molds with similar structures and different specific dimensional requirements. Once the problem of the flanged unloading is solved, the integrated assembly between the mating dimensions and the loading of the hand or the wooden hammer can be ensured, and the excessive fit with a small gap can be used, thereby facilitating the centering accuracy during assembly. Comprehensive assembly quality. In short, the realization of ensuring the excessive clearance of the small gap is an important whole problem to ensure that the spiral ring and the top edge of the bucket and the hole are not easily leaked under any external force. Because from the sealing theory, the wire seal is much better than the surface. It is best to achieve a small clearance fit between the outer diameter of the coil and the inner diameter of the flange. In this sense, it is understood that the sealing achieved after the improvement of the mold, the convenience of operation, the improvement of production efficiency, the compact and reasonable structure, and the enhancement of the service life of the mold are all related systematic work. The lack of that link is not acceptable.
V. Key points and methods of structural improvement design
The main points and methods for improving the design of the 200-liter steel drum barrel top-hole flange forming composite mold structure are:
1. The main points and basic methods for keeping the original convex and concave molds and the punches fastened to the lower mold base and the upper mold are unchanged.
2. The spring force and stroke of the return spring due to the elastic action are not very strict, and the requirements are not very strict. The purpose is to make the unloading device reset, and it is not strictly limited by the structural conditions, so it is not necessary to specially design a special spring. Appropriate selection of a ready-made spring can solve the problem of unloading and resetting of the mold;
3. Focus on the shape of the unloading sleeve and the positioning movement accuracy, and design the original punch to be hollow and have a groove shape that is all-passed in the radial direction and closed in the axial direction; not only is it beneficial to the punch itself. The fastening on the shank also considers the coupling of the unloading link, the movable connecting pin, the unloading sleeve, etc., and the unloading movement of the small distance in the axial direction.
4. Reasonably design the dimensional relationship between the unloading sleeve and the convex and concave molds in the axial direction and the radial direction; the mold does not undergo any adjustment during punching, flanging, forming, unloading and working. Mutual interference involves the phenomenon of collision.
The improved composite structure of the top of the bucket has a reasonable structural design, a simple manufacturing process, and is easy to assemble and adjust. From the rationality of the overall structural design, the punching, flanging, forming and unloading of the mold can be reliable, and the adjustment is simple during use. Compared with the general punching, flanging, forming, and composite molds, there is a certain degree. Versatility. The problem of flanging and unloading in the same mold was successfully solved.
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