a Corresponding author: sungm35@kc.co.kr

Study on the Application of Electron Beam Welding to Automatic Transmission Parts

S.M.Lee1,a, W.Y.Byeon1 and D.J.Cha1 1Kyung Chang Industrial Corp., 6, Seongseoro 35-gil, Dalseo-gu, Daegu,Korea

Abstract. Recently, the study on the automatic transmission technology(such as lightweight of automatic transmission case or using aluminum/magnesium materials) for improving to the vehicle performance and fuel economy is being accelerated. In this study, the electron beam welding, one of the high-density energy welding method, is applied to manufacture the automatic transmission parts. In order to evaluate the characteristic of electron beam welding, an experiment was performed to analyze the effects of welding parameters on bead width and penetration depth. In this study, hub clutch-brake assembly was applied to the experimental target item. In order to apply the electron beam welding to automatic transmission parts, the process parameters of electron beam welding to satisfy of product specification were derived. And then, through the torsion test, the satisfaction of torsional strength of welding product is confirmed.

1 Introduction The automatic transmission consists of the precisive

parts such as clutch pack, carrier and torque converter. So, the process for the production of automatic transmission parts is very important [1]. Especially, according to the development of automatic transmission, the relative importance is on the rapidly increase. Recently, the welding technology using high-density energy source has become an issue. There are many kinds of method in the high-density weld; laser beam welding, electron beam welding and plasma arc welding etc. In this study, electron beam welding method was applied in the manufacture of automatic transmission components [2].

Fig. 1 Schematic view of the apparatus for EBW

Principle of electron beam welding is as follows; the electron beam by focused of high density is fired at the work-pieces under the vacuum atmosphere. By an

electron clash of high speed, high energy is generated instantaneously. At this time, the work-pieces is joined using heat source by generated of high energy. Fig. 1 is the schematic view of the apparatus for electron beam welding. Bead shape of electron beam welding is very narrow, deep wedge-shaped forms compared to using in general conventional welding. So, the product that required the precision and high quality is widely used [3, 4, 5]. In this study, in order to lightweight of automatic transmission parts, electron beam welding process is applied to manufacture the hub clutch-brake assemble. The optimum process parameters are determined from experiments. And torsion test is carried out to verify the welding strength.

2 Evaluating characteristic of EBW At the production of automatic transmission parts

using electron beam welding, the most important element is to satisfy penetration depth and bead width. So in order to understand characteristic of element, experiment was performed. Material used in this experiment is SAPH440 for automobile structural with a thickness of 5mm.

Table 1. Process parameters of electron beam welding

NO Beam

Current(mA) Welding

Speed (mm/min)

Vacuum (Torr)

Distance (mm)

1 21 300~700 1.2 x 10-4 100, 150

2 19 300~700 1.2 x 10-4 100, 150

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3 16 300~700 1.2 x 10-4 100, 150

4 13 300~700 1.2 x 10-4 100, 150

5 10 300~700 1.2 x 10-4 100, 150

* Acceleration Voltage (kV) : 60

The process parameters to find an optimal condition of electron beam welding is as follows; the acceleration voltage 60kV, vacuum 1.2x10-4 is fixed and beam current(10~21mA), welding speed(300~700mm/min), working distance(100mm, 150mm) is changed.(Table 1) Fig. 2 is the weld bead shape by process parameters of electron beam currents.

Fig. 2 Bead shape by the conditions of EBW

Through this experiment, according to the change of

welding currents and speed, the penetration depth and bead width can see that changes in proportion.(Fig. 3)

Fig. 3 The change of penetration depth & bead width by

the welding current & speed

3 The application on the EBW of automatic transmission parts

In this study, in order to apply the electron beam

welding of automatic transmission parts, the process parameters of electron beam welding to satisfy of product specification were derived. And then, through the torsion test, the weld zone strength was verified.

Fig 4. The target item of experiment & weld zone cross-

section

In this experiment, hub clutch-brake assembly was applied to the target item. It is welded with the hub clutch(SPFH590 6.5t) and the hub brake(SAPH440 2.5t). Fig. 4 shows the target item of experiment and the cross-section of weld zone. Table 2 is the welding specification and results of experiment values. Bead width and penetration depth obtained good results. Fig. 5 is the organization in weld zone of hub clutch-brake assembly. In this figure, the organizational changing trends of weld zone and heat affected zone can be seen. Table 3 is the electron beam parameters to satisfy the welding specification used in this experiment.

Table 2. Welding conditions & results of experiment values

Bead width

Penetration depth

Torsion strength

Welding specification 2mm↓ 1.5mm↑ 495N-m

Results of experiments 1.88mm 1.6mm 1,800N-m↑

Fig. 5 The organization in weld zone of hub assembly

Short title of the conference

Table 3. Electron beam welding parameter

Beam current

(mA)

Focus current (mA)

Welding speed

(mm/s)

Slope up angle

(degree)

Slope down

(degree)

27 560 45 15 45

In order to verify the torsional strength of welding product, torsion test were conducted. The torsion test was carried out by the rotary manner using the MTS equipment. Fig. 6 is shown the results of torsion test. As shown in Fig. 6, welding product is not broken at 1,800N-m. As a result of this view, the reliability of product that applied on the electron beam welding was verified.

Fig. 6 results of torsion tests & test conditions

4 Summary

In this study, the electron beam welding is applied to manufacture the automatic transmission parts. In order to evaluate on the characteristic of electron beam welding, an experiment to satisfy conditions on characteristic of bead width and penetration depth was performed. As a result, the welding parameters that satisfied on the product specification were derived. And then, through the torsional test, the reliability of weld zone was verified.

References 1. B.J. Kim, E.S. Park, W.Y. Byeon, D.J. Cha: Study

on manufacturing technology of the drum clutch for

automatic transmission, Steel Research International special edition; metal forming2012, p.1415-1418

2. C. Y. Shin: Characteristics of Electron Beam Welding and Current Situation of Its Technology in Korea, Journal of the KWS, Vol. 18 no. 5, (2000), p.18-24

3. AWS: Welding handbook 7 edition, Vol. 3, 180 4. J.W. Yun: Electron beam welding system, Journal of

the Korean welding society, Vol. 18 no. 5, (2000), p.13-17

5. Dipl. Ing. H. Schultz: Electron beam welding, Abington Publishing, (1993)