Finite Element Analysis of Jumbo Rig Assembly for Tunneling

YAO Haiping

(Zhangjiakou Xuanhua Huatai Mining & Metallurgical Machinery Co., Ltd., Zhangjiakou 075100, China)

Abstract：This paper describes the force acting the assembly of the jumbo rig for tunneling. The finite element analysis is used to calculate this machine structure on its different working states.

Keywords： jumbo rig for tunneling; fea; stress; deformation; failure analysis

1 Introduction

The assembly of the machine is named the connecting base[1], which is located on the middle of the working arm, as shown in Figure 1. One side of the connection base is circular cylinder, that is fixed on the upper arm. And it can rotate with the rotation cylinder. The other side is connected the rock drilling rig. Let the rock drilling rig move along with the line of the structure.

Figure 1 Connecting base

The original structure of the connecting base is only circular cylinder. This original body limited the action of the working arm. There are more location of the drilling holes could not arrived, because of the interferes of the structure itself.

2 Working state

There are two different working conditions that is described in this paper. One is the vertical hole, the other is horizontal hole.

When the vertical hole is drilling, the posture of the body see the Figure 2. The hole is located on the direction of the positivey-axis. And the rock drilling rig can not feed when the hole is drilling. That mean is that the reactive force of the rock to the machine is equal to the force of the rock drilling rig[2]. And it act on the end of the surfaceA, see the Figure 2, its value is 15 000 N. Its direction is normal to the action face toward upward[2]. The weight of the structure have two part. One is the weight of the model used by analysis software[3]. The other is the actual weight, Table 1 shows the loading of the vertical hole. The weight value in the Table 2 is the difference between the two part of the weight. And the location of the Table 1 is the middle of the location in the cartesian coordinate.

Figure 2 Vertical drilling

Table 1 The loading of vertical hole

The second state of working is drilling the horizontal hole on the tunel corss-section. The drilling hole is the position of the negative direction of thez-axis, see the Figure 3. And the value of the loading, acting on the structure see the Table 3. The horizontal drilling, and the reaction force is also 15 000 N, and the direction is horizon pointing to the negativezaxis. Two part of weight need to load the structure, making sure that the loading condition similar to the actual condition.

Figure 3 The horizontal drilling

Table 3 The loading of horizontal drilling

3 Stress analysis

The material is structural steel, selected from the steel structure of the Ansys material library[4].

The fatigue failure analysis is necessary[5-7]. The repeated loading act on the connection base. Even though the value of the repeated load is much less, the arm assembly may fail. Based on the Gerber failure criterion[8], the result of the two state of working see the Figure 4 and Figure 5.

Figure 4 The fatigue failure of vertical drilling

Figure 5 The fatigue failure of horizon drilling

For the coefficient of safety[9], the minimum magnitude of drilling the vertical holes is 3.4, and the minimum of value of the horizon drilling working condition is 1.6.

Comparison the two data of the minimum coefficient of safety[9], we know the state about drilling the vertical holes is better than the working drilling the horizon holes.

So next step, the statics analysis is only performed to the structure of the state of drilling horizon holes[4]. The results, based on the finite element method[5-6], show that the maximum equivalent stress[8]of the all structure is 53.075 MPa, as shown in Figure 6. The minimum of the safety factor about the maximum shear stress[3,10]is 4.10, as shown in Figure 7.

Figure 6 Equivalent stress

Figure 7 Safety factor

4 Conclusion

Comparison the two working state, the all calculating data of the horizon state is not good. For the fatigue failure analysis[8,11], the coefficient of safety of the horizon working state is 1.6. The value is greater than one. About the static analysis, the safety factor of the max shear stress is 4.10. While the safety coefficient of the handbook of the heavy machine is from 3 to 5. The value of the safety coefficient of the static analysi meet the standard value. So the mechanical structure can be installed the drilling device.