Vol. 56 No. 2

Material Science and Technology of Japan, 56（2019）77～72

35

Regular Paper
Development of Die Cushion Device for Press with Frictional Force
Takao ITO 1,2,*, Osamu TAKAI 3
1

Doctoral Course in Interdisciplinary Engineering,Graduate School of Engineering, Kanto Gakuin

University, 1162-2 Ogikubo, Odawara 250-0042, Japan
2Aida engineering, ltd Research & Development Headquarters , 2-10 Ohyama-cho ,midori-ku ,Sagamihara , Kanagawa 252-5181 , japan
3

Materials and Surface Engineering Research Institute, Kanto Gakuin University, 1162-2 Ogikubo,Odawara 250-0042, Japan

Received Dec. 4th, 2018; accepted for publication Dec. 19, 2018
Abstract
A frictional force is generated by sliding between metal portions of a shaft part and a hole part having an interference,and such a frictional force is used as a die cushion force of a press. In this way, a die cushion device can bedownsized. In addition, since the frictional force calculated from the interference δ matches the actual measured
frictional force in a test, it is possible to acquire the desired frictional force by managing a dimension of theinterference. We conducted a reciprocal sliding experiment for 600,000 times and could consequently acquire theconstantly stable frictional force and constantly stable temperature transition of sliding portions. Furthermore, nowear was found in an outer diameter of the shaft part and an inner diameter of the hole part after the experiment.
Therefore, we were able to prove high durability and long life of the die cushion device.
Keywords: Frictional Force, Surface Treatment, Die Cushion Device, High Durability, Interference Fit Sliding

1. Introduction

to realize high precision forming of ultrahigh-tensile-strength

1.1 Background of press processing

steel, which requires high die cushion force.

In recent years, the reduction of greenhouse gas has beenpromised to deal with global warming, and weight reduction of

1.2 Current issues

the car body structure is indispensable, in the automobile

A pneumatic die cushion cylinder is usually placed in a pressedindustry, as a measure to improve fuel efficiency.

frame [1], and a pneumatic pressure thereof during use is 0.5 to 1

In order to reduce weight of the car body structure, eachMPa. In order to improve the capacity of the die cushion at thisautomobile manufacturer focuses on the development to expand

pneumatic pressure, the pneumatic cylinder having a large

the adoption ratio of ultrahigh-tensile-strength steel.

effective cross-sectional area is required. As a result, rigidity of

The role of the die cushion device in the conventional press sheet

the pressed frame that requires a space for accommodating theforming is to prevent wrinkling during forming, and a press

cylinder in a large outer shape is lowered, which possibly

machine is equipped with the pneumatic or hydraulic die cushion

degrades dimensional precision of a product and possibly causes

device in general.

a wrinkle or a crack on a formed part.

In those devices, cushion force, arrangement of cushion pins

Fig. 1 illustrate a difference in a wrinkle prevention effect thatand other specification are determined as a part of the pressis exhibited in the actual forming process due to different

machine specification.

magnitudes of the die cushion force [2,3].

This means that it is hardly possible to change the specification

The blank holder in (a) pushes the flange portion of the material*Corresponding author: itotaka@aida.co.jp(77)