Metal deforming – By use of non-deforming work-gripping clamp and relatively... – Clamp structure constitutes sole initial metal-deforming...
Patent
1985-04-01
1987-04-21
Crane, Daniel C.
Metal deforming
By use of non-deforming work-gripping clamp and relatively...
Clamp structure constitutes sole initial metal-deforming...
72323, 72461, B21D 504
Patent
active
046586245
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an improved bending machine for forming bends on the edges of sheet metal panels.
The most generally used method of forming bends in sheet material is by means of male and female vee shaped tools in a conventional press brake whereby the sheet material is fed into the tools in a horizontal plane and the sheet at each side of the fold line is raised upwards as the bend progresses.
In the case of a narrow fold on the edge of a large panel it is necessary to manually support the main body of the panel throughout the bending process and also when the tools retract and leave the workpiece unsupported. Handling problems are also caused when successive bends in opposite directions are required, entailing sheet turnover between bending operations. A further disadvantage of the vee tool method is the damage to the sheet surface which commonly occurs where the point of the male vee and the two corners of the female vee contact the material.
A method commonly used in presswork to form one or more edges of a panel simultaneously is to clamp the main body of the sheet and apply a force perpendicular to its surface at or near the point where the bends are to be formed until the sheet material bends. This method normally requires a special tool for each different size of panel and may also result in marking of the material where there has been a peak of pressure applied in forming the bend.
One bending machine which uses this method of bending sheet material is described in UK Patent Publication No. 2004216A. The machine is a fully automatic bending machine requiring no manual intervention and is designed primarily for bending the edges of sheet material to form a shallow rectangular box, tray or panel. The sheet of metal is held in its centre by a vice which is used to slide the sheet material towards a forming tool and is also used for rotating the sheet of material so that a different edge of the sheet material is facing the forming tool.
The machine includes a bending press which includes two vertically facing bending blades which have a reciprocating motion so that the bending blades pass towards and through the plane of the sheet material to form a bend. The face of each bending blade is planar and so as the blade comes into contact with the sheet material it has a tendancy to slide along the material which can cause marking of the material. The application of the load is at one point and thus as the bending blade moves towards and through the plane of the sheet material the force on the sheet material is not constant. In cases where the sheet material has a treated surface such as a plastic coating this will cause creasing and marking which is unsatisfactory.
An improvement to the bending maching is enclosed in European Patent Publication No. 23894. In this machine at least one of the bending blades is adjustably movable towards and away from the clamp which holds the sheet material so that a first portion of the bend is carried out by applying force at a first distance from the bend and then the bending is completed by applying force at a second position closer to the clamp means and the finished bend. However the apparatus required for achieving this movement of the bending blade towards and away from the bend is very complicated and makes the finished machine very costly.
The bending blades of this bending machine are mounted on a C-shaped mounting tool. This means that the distance of the bend to the edge of the material is limited by the depth of the throat of the C-shape mounting tool. This means that the machine can only be used for forming bends very close to the edge of the sheet of material. Additionally the depth of throat restriction prevents the use of a variable position back stop.
According to this invention there is provided a bending machine for forming bends in sheet material including clamp means for clamping part of the sheet material and a forming tool with which force is applied to the unclamped part of the sheet material to effect a bend, characterised in that the f
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Coultish John R.
Ridgway Charles I.
Crane Daniel C.
Joseph Rhodes Limited
Lewen Bert J.
Sternberg Henry
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