Using the Pressure Intensifiers in Hydraulic Units of Heavy Duty Machine Tools

Headnote

Abstract: This paper presents some applications of the pressure intensifiers used in the hydraulic units of the clamping/unclamping systems and unloading systems for the guideways of HBM and GANTRY type heavy duty machine tools. The paper makes a comparison between the systems with and without pressure intensifiers. There are presented mathematical models for the pressure intensifiers and the results obtained after a simulation using specialized programs.

Keywords: Pressure intensifiers, machine tools, guideways unloading systems

(ProQuest: ... denotes formulae omitted.)

1. Introduction

The operating principle of the pressure intensifiers [1, 2, 3] is shown in Figure 1.

If the cylinder 1 is supplied with the flow Q₁ at the pressure p₁ on the path A, the piston 2 moves in the pressure chamber 3 providing the consumer C with the liquid flow Q₂ at the pressure p₂. The pressures are read on the pressure gauges 4 and 5.

The pressure and the flow obtained depending on the surfaces S₁, S₂ and S₃ are the following ones:

... (1)

... (2)

In the absence of losses, the flow-pressure characteristic in stationary mode for the intensifier of Figure 1 is shown in Figure 2.

The two rectangles in Figure 2 have the same area equal to power P, where:

... (3)

Consumer C can be a cylinder; in this case the flow Q₂ will feed a chamber of limited variable volume or an open circuit such as the systems of liquid jet cutting, in which case the flow Q₂ should be continuous.

2. Hydraulic systems for guideways locking/unlocking and unloading

In the case of machine tools, the pressure intensifiers are used for powering the clamping/unclamping systems of the blanks or, in some situations, for powering the guideways unloading systems [1, 4]. In this case, the consumers C can be the single-acting hydraulic cylinders or, in the case of CNC machine tools [1], the double-acting hydraulic cylinders.

Figure 3 shows the actuation schemes for these systems.

Figure 3 uses the same notations as in the previous figure, plus: 6 - consumer cylinders with useful area S, CV₁, CV₂ - one way check valves and HPDCV - Check valve hydraulically operated.

If the liquid supply...