Lifting heavy pliers is an important tool for lifting steel plates, etc. The clamping force between the pliers tongue and the steel plate is an important factor affecting the stability of the lifting pliers of the lifting steel plate. If the clamping force between the lifting pliers tongue and the steel plate is too large, the steel plate will be damaged and the life of the jaws will be shortened. Causing the lifting pliers to break; If the clamping force between the tongue and the steel plate is not large or insufficient, the steel plate slip phenomenon will occur, and the above phenomena will occur. In this chapter, through the structural analysis of vertical lifting heavy lifting pliers, we find out the effective ways to solve the above problems affecting the lifting steel plate by vertical lifting heavy lifting pliers. General situation: At present, the domestic research on vertical lifting of heavy lifting tongs is mostly on small tonnage, and there is certain experience

　　According to objective results, there are certain difficulties in developing and stereotyping new products. The author through the vertical lifting of heavy lifting pliers points

　　The purpose is to seek a theoretical basis for the development of vertical lifting heavy lifting pliers and a new idea for the design of vertical lifting heavy lifting pliers.

　　First, the current problems of vertical lifting of heavy lifting pliers

　　1. When lifting the heavy lifting pliers to lift the steel plate, the clamping force between the tongue and the steel plate is not enough, the steel plate is easy to slip, and the use is unstable.

　　2. When the heavy lifting pliers are hoisted vertically to lift the steel plate, the steel plate is easily damaged when the pliers tongue contacts the steel plate.

　　3. The weight of lifting heavy pliers is too large and inconvenient to use.

　　Second, the solution

　　1. The tooth shape structure is designed at the contact parts of the clamp tongue and the support platform to improve the friction coefficient, and the selection of the tooth distance size ensures not only the steel plate is not damaged but also the friction coefficient;

　　2. Reasonably distribute the relationship between the joint arm and the lever arm of the clamp tongue under the premise of ensuring lightness, so as to improve the clamping force.

　　3. To ensure that the surface of the steel plate is not damaged. Take the following measures:

　　4. When the clamp tongue and the support platform clamp the steel plate, the force surface is parallel to the steel plate;

　　5. The contact surface between the tooth shape of the clamp tongue and the steel plate should be increased as much as possible, and the supporting surface of the support platform is a ring groove. The implementation of the above measures greatly reduces the possibility of steel plate damage.

　　6. In order to ensure the lightness of vertical lifting heavy lifting pliers, after multiple arguments, the structure of vertical lifting heavy lifting pliers is improved as follows:

　　7. The clamp body is hollow, and the left and right clamp plate is connected with the pillar and the clamp block, which greatly reduces the weight

　　8. The pillar and pin are made of alloy structural steel to increase the strength, thereby reducing the weight, so as to achieve the light use of heavy lifting pliers

　　then

　　Iii. Verification

　　1. In order to check the performance of the vertical lifting tongs, the crane and the hook with load display instrument were used to carry out the static load test of 2 times load, the breaking test of 4 times load and the dynamic load test of 1.25 times load. And through magnetic particle inspection, ultrasonic inspection. The test results show that there are no cracks, no deformation and other deformation which affect the performance and stability after 2 times static load and 1.25 times dynamic load test. During the 4 times load breaking test, the body of the heavy lifting pliers is deformed, but the steel plate does not slip, which meets the design requirements.

　　2. The on-site use meets the requirements, and there is no slip of the steel plate.

　　Conclusions

　　The vertical lifting heavy lifting pliers first adopts low-alloy high-strength structural steel Q345B and implements hollow structure, which is light and strong

　　Degree requirements; Secondly, under the premise of ensuring lightness, the relationship between the coupling arm and the lever arm of the clamp tongue is reasonably distributed, and the appropriate tooth shape is designed in the contact parts between the clamp tongue and the support platform. At the same time, the contact surface between the clamp tongue and the support platform and the steel plate is increased as much as possible, so as to increase the friction force and achieve the purpose of not damaging the steel plate. Proper heat treatment of the tongue and the teeth of the support platform greatly improves the service life of the vertical lifting of the heavy lifting pliers.

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