SU1447692A1 - Method of two-axis positioning of thermoplastic sheets - Google Patents

Abstract

The invention relates to the processing of plastic sheet materials. In order to reduce waste, sheet 1 is fixed with half of the total number of grippers 2, heated to a highly elastic state, the grippers and materials under them are cooled using a special system and stretched to half a linear stretch. Then the sheet is clamped with the grips 3 of the second half, they are cooled and the material beneath them, and a full linear stretch is made. .M. After this, a sheet of охлажд € 1moplast is cooled. i il .. 1 tab.

Description

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This invention relates to the field of processing thermoplastic sheet materials and can be used in the manufacture of sheets of organic glass.

The goal is to reduce waste.

The drawing shows a diagram explaining the method.

The diagram shows: 1 - thermoplastic sheet, 2 - the first half of the grips initially fixed evenly distributed around the sheet perimeter, 3 - the second half of the grips, placed evenly between the originally fixed grips.

The method is carried out as follows.

The thermoplastic sheet 1 is fixed with half of the total number of grips 2, heated to a highly elastic state, the grippers and material under them are cooled using a special system (not shown) and stretched to half a linear stretch, then the sheet is clamped with the grips 3 of the second half, cool them, make a full stretch of the sheet and cool it.

Example 1. A sheet of plexiglass with dimensions of 1000 x 50 mm was taken for stretching. The desired draw ratio is HB 70%. Billet secured half of the total number of seizures. Measured the distance between the opposite grippers and calculated the value of the linear stretch by the formula

where I is the distance between opposing grippers; HU - the degree of stretching in percent

, 890-70 01 q ,,

Preheat the preform to a highly elastic-fioro state, cool the grippers and the mat

The rial under them, stretched up to half of the linear stretch, clamped the workpiece with the claws of the second half, cooled them and the material under them and produced a full linear stretch of the workpiece.

Overall dimensions of the drawn sheet: 1623X1623 mm. Technological waste: 100-110 mm per side according to the permissible optical characteristics in the areas of captures. The yield of the useful area is 75-76%.

For comparison, the same preform was stretched according to the prototype method, i.e., on a plant with a shakht arrangement of grips in rows. The distance between the opposite grippers is 800 mm. Overall dimensions of the expanded sheet: 15.60Х Х1560 mm. Process waste: 150-160 mm per side. The output of the usable area is 60,, 6%.

The results of comparisons when extracting sheets using the old and new methods with different degrees of stretching are tabulated.

The result shows that the proposed method can reduce waste by an average of 10-12%.

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Claims (1)

Invention Formula Method of biaxial orientation of sheets of thermoplastics by drawing, including fixing uniformly arranged grippers along the perimeter of the sheet, heating the sheet with simultaneous cooling of the grippers, drawing of the sheet by moving the grippers and its subsequent cooling, characterized in that, in order to reduce waste, the drawing is carried out step by step, in the first stage - by half of the total grips up to half of the linear stretch, and in the second stage, the total number of grips to complete linear stretch, while the second half of the grips are placed around the perimeter of the stretched sheet evenly between the initially fixed grips.