Shear die for parts cutting from thick-wall rubber

FIELD: process engineering.

SUBSTANCE: invention relates to machine building, particularly to production of assembly units and part made of thick rubber, over 20 mm, of various shape, and can be used in production of rocket engines. Shear die comprises plate with cutting element secured thereat composed of cutter unit, pusher to drive extractor for removal of cut parts and wastes. Note here that shear die is provided with extra lower side blade unit for cutting of parts from both sides arranged on mating side of upper blade unit. Two stiff thrust incorporated with said die guarantees the clearance which rules out contact between blade cutting edges to contact solely with rubber material. Blade sharpening angle is defined by claimed formula.

EFFECT: sharpening edges is decreased from 16÷18° to 6÷8°, ruled out breakage and blunting thereof, higher accuracy and quality of cut parts.

1 dwg

The invention relates to the fields of engineering, where used parts and components of heavy-gauge rubber more than 20 mm in various fields, and can be used, for example, in the production of rocket engines.

Details of thick-walled rubber should have a vertical cutoff wall and profile with strict requirements on geometry. When the rubber thickness over 20 mm notch parts of an ordinary knife stamp is accompanied by tightening of the walls, whereby the cut surface is not perpendicular to the plane of the sheet of rubber. In addition, the knife is stamped in the end of your turn rests on a rigid lining, which leads to blunt and chipping knife-edge (of Teeth M. E. Sheet-metal stamping, Leningrad: Mashinostroenie, 1980, p. 338).

To escape from the tightening of the walls, in practice, the cutting parts are made of thick rubber made on machines for mechanical processing of metals. This technique has significant disadvantages: low productivity and large waste of material.

The technical result, which directed this invention is the high purity of the slice cut out details, a decrease in the angle knife sharpener with 16÷18° to 6÷8°, with the exception of breakage and chipping of the edges of the cutting elements producing the items of thick-walled rubber with vertical walls relative to the plane of the sheet, ensuring a high PR�of performance. To the claimed technical solution for cutting non-metallic materials it is recommended to take an angle α 16÷18° (RTM 34-65 Dies for cold sheet metal forming. Calculations and design. M.: Publishing house of standards, 1966, p. 49-50).

This technical result is achieved due to the design of the blade stamp for cutting parts out of thick rubber. Knife stamp contains a die plate fixed thereto, a cutting element made in the form of a blade unit, a pusher to actuate the puller to remove the cut parts and waste. This knife is a stamp provided with an additional lower blade unit for cutting parts from two sides and is located on the return side of the upper blade unit. The presence of the stamp 2 hard stops ensures the gap, providing the exception of contact of the cutting edges of the knives, only contact with cut material. The angle of taper of the knife is determined by the formula:

$$tg\alpha =\frac{b}{H}$$where

b - the thickness of a knife, mm;

H - height of the sharpened part of the blade, mm.

$$H=\frac{S}{2}+X$$where

S - rubber thickness, mm;

X - allowance for regrinding of the knife, mm.

The drawing shows the blade stamp for cutting parts out of thick rubber.

The stamp works as follows.

Cutter die for cutting parts of thick-walled rubber works on a hydraulic press P-311. In the open position of the press stroke, the workpiece is placed on the lower cutting edges of the blade unit. After a slide stroke of a press, with a fixed upper blade unit, the clipping parts from 2 sides simultaneously. Limitation slide stroke are hard stops 9 mounted on 2 columns 7.

After cutting out the parts and slide stroke upward traverse of the press through the pushers 12 and a spreader knife stamp 14 doffer 10, make a removal of parts and waste from the top of the blade unit. The removal of parts and waste from the lower section to produce hydromedusae press in pushers 13 con�nick 11.

Example

Select the rubber plate 2F-1-IBS-C according To GOST 263-75.

1. The thickness of the rubber S=30 mm;

The thickness of the blade b=2.5 mm. This value is accepted in a constructive and depends on the thickness of the rubber S.

$$H=\frac{S}{2}+X$$where X is the allowance for regrinding of the knife, mm, constructively accepted 3÷5 mm. Take X=5 mm.

$$H=\frac{S}{2}+X=\frac{30}{2}+5=20mm$$;

$$tg\alpha =\frac{b}{H}=\frac{\mathrm{2,5}}{20}=7^{\circ }10\text{'}$$

2. The thickness of the rubber S=40 mm;

The thickness of the blade b=3.0 mm.

$$H=\frac{S}{2}+X=\frac{40}{2}+5=25mm$$;

$$tg\alpha =\frac{b}{H}=\frac{\mathrm{3,0}}{25}=6^{\circ }50\text{'}$$

3. The thickness of the rubber S=50 mm;

T�Lina knife b=3.4 mm.

$$H=\frac{S}{2}+X=\frac{50}{2}+5=30mm$$;

$$tg\alpha =\frac{b}{H}=\frac{\mathrm{3,4}}{30}=6^{\circ }27\text{'}$$

Thus, the proposed design of the cutter die for cutting parts of thick-walled rubber is such that the blades contact with cut material, which reduces the angle knife sharpener with 16÷18° to 6÷8°, eliminates breakage and chipping of the edges of cutting elements and their intense dull and also improves the accuracy and quality of cut parts.

Cutter die for cutting parts of thick-walled rubber containing a die plate fixed thereto, a cutting element made in the form of the top of the blade unit, the pusher actuating the puller to remove the cut parts and waste, characterized in that it further provided with a lower blade unit which is mounted on the return side of the upper blade unit for cutting parts from two sides, and two hard stops for the education gap, providing the exception of Abrikosov�of the cutting edges of knife blocks and contact them with cut material, and the angle of taper of the cutting edge of knife blocks is defined by the formula:
where
b - thickness of the blade unit, mm;
H - height of the sharpened part of the blade unit, mm;
where
S - rubber thickness, mm;
X - allowance for regrinding the blade unit, mm.