JPS61255790A - Overload preventive device for crank press using link and hydraulic cylinder - Google Patents

Abstract

PURPOSE:To make possible the prevention of the overloading of a crank press by connecting an upper link fitted pivotally to a crank pin and a lower link connected to a lower slide via a gudgeon pin to a chevron shape by means of a knuckle pin. CONSTITUTION:The upper link 3 is fitted pivotally to the crank pin 2 of a crank shaft 1. The slide 8 and the lower link 6 are connected by the gudgeon pin 7. The upper and lower links 3, 6 are connected by the knuckle pin 4 and a fork 5 is pivotally supported by the pin 4. A piston 10 and rod 9 in a cylinder 11 are fully extended so that the center of the pin 4 is held offset by a prescribed distance X from the straight line connecting the centers of the pin 2 and the pin 7 when the pin 2 is at the bottom dead point. An oil pressure is always generated on the right side of the piston 10 at the upper limit of the slide 8 and the max. pressure thereof is controlled by a relief valve. The overloading of the crank press is thereby prevented and the maintenance thereof is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Related Industrial Field) The present invention relates to an overload prevention device for a crank press.

(Prior art) The overload prevention device in conventional crank presses is installed between the ring-shaped piston installed under the nut fitted in the adjustment screw installed at the tip of the gudgeon pin and the cylinder inside the overload protector inside the slide. The structure used a relief valve to control the hydraulic pressure generated.

This not only complicates the structure within the slide and is inconvenient when receiving an impact load, but also increases the size of the slide itself.

Additionally, a hydraulic unit was built into the slide, making maintenance difficult.

(Problems to be Solved by the Invention) To obtain an overload prevention device without increasing the dimensions of the slide, to provide an overload prevention slide unit outside the slide to facilitate maintenance, and to simplify the configuration. The challenge is to make it more difficult for trouble to occur.

(Means for solving the invention) An upper link pivotally connected to a crank pin and a lower link connected to a slide via a gudgeon pin at the lower part are connected by a knuckle pin, and a piston rod is pivotally connected to the knuckle pin,
The center of the knuckle pin is offset by a predetermined distance from the straight line connecting the centers of the crank pin and gudgeon pin to form a dogleg shape, and pressurized oil whose maximum pressure is always controlled is applied to the right side of the piston at the upper limit of the slide to overcome this pressure. Overload is prevented by setting the load prevention setting pressure.

(Example) In FIG. 2, the symbol ``■'' indicates a crankshaft, and the upper link 3 is pivotally attached to the crankpin 2 portion.

Reference numeral 4 designates a knuckle pin that pivotally supports the lower link 6, the upper link 3, and the fork 5 provided at the tip of the rod 9. 7 is a gudgeon pin that connects the lower link 6 and the slide 8.

A piston 1O is attached to the rear end of the rod 9, and the piston moves left and right within the cylinder 11. 12 is a pin fixed to the frame.

As shown in Fig. 1, when the crank pin 2 is at the bottom dead center, the piston 10 and rod 9 in the cylinder 11 are fully extended, and the center of the knuckle pin 4 is a straight line connecting the centers of the crank pin 2 and the gudgeon pin 7. The dimensions of each part are determined so that they are offset from each other by a predetermined distance χ. It is also assumed that hydraulic pressure is always generated on the right side of the piston 10 at the upper limit of the slide 8, and that the maximum pressure is controlled by a relief valve.

(Function) If an overload P occurs on the slide 8, the upper link 3
Due to the offset χ of the knuckle pin 4 of both the lower link 6 and the lower link 6, a pushing force F is generated on the rod 9. This F is very small compared to P. For example, when the load P on the slide 8 is 100 tons, the load F on the piston 10 is 7 tons. Now, the load F on this piston is prevented from exceeding the set force due to the relief valve (not shown), so if the slide 8 descends so that the overload continues, that is, the crank pin 2 When approaching bottom dead center, piston 10
, the rod 9 moves to the right inside the cylinder 11, χ becomes large, and the slide 8 does not fall even when the crank is lowered, so overload is prevented.

(Effects) Instead of the conventional connecting rod, it is constructed with two upper and lower links, and the upper and lower links are bent in a square shape to prevent overload of the crank press.
■An overload prevention device can be installed without increasing the size of the slide. ■Since the overload prevention slide unit is located outside the slide, there are no maintenance problems. ■Because there are no complicated parts inside the slide, which can be subject to high impact, troubles are less likely to occur.

[Brief explanation of the drawing]

Figure 1 shows the overload prevention device of the present invention. FIG. 2 is a sectional view of the slide drive mechanism. In the figure, 1 crankshaft 2 crank pin 3 upper link 4 knuckle pin 5 fork 6
Lower link 7 Gudgeon pin 8 Slide 9 Rod 10 Piston 11 Cylinder 12 Pins and above Applicant Sumitomo Heavy Industries, Ltd. Sub-agent Patent attorney Isamu Ohashi Figure 1 Figure 2

Claims (1)

[Claims] The upper link (3), which is pivotally connected to the crank pin, and the lower link (6), which is connected to the slide (8) through the gudgeon pin (7) at the lower part, are connected by a knuckle pin (4), and the knuckle pin (4) The piston rod (9) is pivotally connected to the piston rod (9), the center of the knuckle pin (4) is offset by a predetermined distance from the straight line connecting the centers of the crank pin (2) and the gudgeon pin (7), and the piston is mounted at the upper limit of the slide (8). (10) An overload prevention device for a crank press, characterized in that pressure oil whose maximum pressure is always controlled acts on the right side of the crank press.