Pneumatic nail gun handle damping material selection and Finite Element Analysis

 

(Taizhou Vocational and Technical College of Mechanical and Electrical Engineering, Taizhou, Zhejiang 318000)

 

Abstract: The pneumatic nail gun will handle the vibration caused great harm to the health of the operator. Currently, domestic Nailer design research in damping is very limited. In this paper, this issue, pneumatic nail gun as the research object, the finite element software ANSYS Workbench as a computing platform damping lever on the pneumatic nail gun holster materials with different vibration acceleration when analyzing the whole gun, pneumatic nailer damping Handle material selected to provide a theoretical basis.

 

Keywords: pneumatic nailer, materials, vibration, acceleration, finite element method

 

CLC: TP29 Document code: A doi: 10.3969/j.issn.1002-6673.2009.06.046

 

Introduction

 

Pneumatic Nailer belongs to the pneumatic impact tools one, it is the use of air compressed gas as a power, the use of labor-saving, high efficiency [1]. However, when using pneumatic nail gun injury to the operator vibration generated healthy, therefore, give full play to its performance under the premise of vibration and should be designed to reduce the vibration level. Pneumatic tools are generally in the handle position packet layer damping materials, pneumatic nailer also use this method damping. To ensure its compact, light weight, bonded to the handle of the thickness of the damping material in a certain range, so the handle is too thick. Within the limited thickness to achieve good damping effect, choose a suitable rubber material becomes particularly important.

 

A damping rubber material

 

Vibration at the handles multi-use rubber holster. Rubber materials are characterized by both high elastic state have high viscosity state, good damping, soundproofing and cushioning properties [2-4]. Nailer leather handle vibration nitrile rubber is generally used, since in many vibration damping rubber material, it has the larger loss factor. The so-called loss factor of said rubber hysteresis and internal friction properties of the parameters, the greater the loss factor, damping effect is more obvious.

 

Based on the choice of the rubber material performance characteristics and test conditions, the choice of two-parameter Mooney-Rivlin model, as the vibration handle leather material model [5]. Since three materials in the specific formulation of different materials have different properties. Therefore, the definition of the material properties, the rubber material respectively, the three uniaxial tensile test, the stress-strain data obtained in Figure 1 to 3.

 

As can be seen from the figure, the same three materials strain tensile stress increases, gradually rubber material that is "hard" material 1 is the "soft" material 3 is the "hard." According to the above stretching data through the fitting parameters to obtain the final material properties. Meanwhile, this paper analyzes the vibration acceleration for the whole gun, which can be neglected in solving various minor differences in material properties between the parts, and the parts to keep the total mass distribution consistent quality and design in a consistent state can.

 

2 whole gun vibration analysis simplified geometric model

 

This paper uses Pro / E software to establish the whole gun geometric model, and then through the Simulation ANSYS Workbench link function modules, the geometry model into [6]. Pneumatic Nailer mainly consists of six components, including aluminum cover assembly on the gun body assembly, the gun clamp assembly, intake cover and switching components, the insurance component. To simplify the analysis process, improve the efficiency of the analysis, finite element analysis is required in the various components of the corresponding simplified. For most closely with the vibration analysis of the gun assembly, which handle holster keep the original design of the state; gun body components for other parts, then simplify the details of the surface characteristics of the gun, according to the principle of mass distribution equivalent simplified; the aluminum cap, gun clamp assembly, inlet cap assembly because the distribution of the acceleration in the analysis would have a significant impact, so these three components appropriate simplified, maintaining an equivalent mass distribution; switch assembly is in the corresponding position of the switch assembly establish a quality unit; through a certain thickness of the ring simulated hand on the handle, leather grip effect.

 

3 whole gun vibration acceleration of the finite element analysis for solving finite element model of the whole gun shown in Figure 4. In order to facilitate and ASM's vibration testing standard for comparison, we use Ansys Workbench provides a flexible body dynamics analysis of vibration acceleration analysis. Leather materials as the main variable with parameters discussed leather material is not the same, the size of the vibration acceleration at the handles, in order to analyze the results of different materials, the entire gun holster vibration, particularly vibration of the handle. Nailer according to the actual working condition, the following boundary conditions are imposed. ① gun clamp assembly protruding from the bottom boundary condition is applied at impact, impact test measured a maximum of 500N, duration of action is approximately 0.01s; ② hand far field applied to the surface boundary conditions, the displacement of the elbow position constraint zero, no limit to the position of rotation; ③ the gun assembly, the aluminum cover assembly, inlet cap assembly, the gun between the actual assembly clamp assembly firmly assembled state, the contact set as a binding. Holster and handle between hands and between the holster and impact force may occur with the emergence of relative sliding or rotation, which can be set between these parts in frictional contact, the contact friction coefficient of friction according to the actual conditions to be defined .

 

4 Analysis

 

Using the flexible body dynamics model gun assembling the whole process of solving, by setting a plurality of sub-step, the impact force is applied to the analog clip gun end, holster constant thickness are 1.0mm, calculate the position of the handle causes the size of the vibration acceleration . Table 1 shows the three kinds of leather material, the entire gun vibration acceleration rms value distribution.

 

As can be seen from Table 1, the change of leather material transmitted to the operator's hand size vibration acceleration of impact. The three materials, the "soft" material No. 1, the handle gripping position corresponding to the minimum vibration acceleration; most "hard" material 3, the handle gripping position corresponding to the maximum vibration acceleration. That is at the same position on the handle, as the rubber material gradually "hard", transmitted to the hands of the vibration acceleration increases, the vibration felt by the operator feel is increasingly apparent.

 

5 Conclusions

 

In this paper, the finite element method for the entire pneumatic nail gun vibration acceleration analysis. The results showed that different leather materials, the handle is passed to the hands of the vibration acceleration operator about 4000 ~ 6000mm/s2, this is Richard's 3940 mm/s2 data compared to the high side, but it is within a reasonable range, with the design reference value. According to the results it can be concluded: Leather handle the materials delivered to the hands of the vibration acceleration of an impact, the rubber material used in leather more "hard", handle vibration transmitted to the hand greater the acceleration, the operator felt vibration touch has become increasingly apparent. Actual use, the materials processing state permit conditions, should try to choose a more "soft" damping rubber material as the handle holster material. As can be seen from Table 1, the change of leather material transmitted to the operator's hand size vibration acceleration of impact. The three materials, the "soft" material No. 1, the handle gripping position corresponding to the minimum vibration acceleration; most "hard" material No. 3, the handle gripping position corresponding to the maximum vibration acceleration. That is at the same position on the handle, as the rubber material gradually "hard", transmitted to the hands of the vibration acceleration increases, the vibration felt by the operator feel is increasingly apparent.