Positioning apparatus for bending machine

Details Positioning apparatus for bending machine Positioning apparatus for bending machine

2001-03-07

2002-07-23

Jones, David (Department: 3725)

Metal deforming

By or with work-constrainer and/or manipulated work-forcer

Comprising work-stopping abutment

C072S389300, C072S016200, C072S017300, C072S420000

Reexamination Certificate

active

06422055

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bending machine, and particularly to a positioning apparatus for precisely positioning workpieces on the bending machine.
2. Description of Related Art
With rapid developments in manufacturing industry, the demand for precision components is constantly increasing. A mechanical manipulator is often used to feed workpieces to a workbench in a bending machine, instead of using manual feeding. In order to precisely positioning the workpieces in the workbench, the manipulator itself must be precisely positioned.
FIG. 4
shows a conventional positioning apparatus
10
behind a lower die
20
of a bending machine (not shown). The positioning apparatus
10
comprises two generally symmetrical positioning blocks
101
. Each positioning block
101
comprises a shoulder
102
with a front surface
103
. Two approaching switches
105
are respectively installed on mutually opposing sides of the two positioning blocks
101
. Each approaching switch
105
extends slightly beyond the front surface
103
of the corresponding positioning block
101
. A post
107
is formed on one of the mutually opposing sides of the two positioning blocks
101
. The post
107
is adapted to prevent the two approaching switches
105
from contacting each other and generating an error signal.
In operation, a manipulator (not shown) takes hold of a workpiece (not shown) and puts it onto the lower die
20
. Then the manipulator horizontally pushes the workpiece toward the positioning apparatus
10
. When the workpiece contacts the approaching switches
105
, the approaching switches
105
are moved backward. The workpiece is continued to be pushed by the manipulator. When front walls (not labeled) of the approaching switches
105
become coplanar with the front surfaces
103
of the positioning apparatus
10
, the workpiece is blocked by the positioning apparatus
10
and is positioned in the bending machine (not shown) ready for bending. A sensor (not shown) electrically connected with the approaching switches
105
sends a signal to the manipulator indicating that the workpiece is positioned ready for bending. The manipulator thereupon stops pushing the workpiece.
The conventional apparatus has a number of shortcomings. The approaching switches
105
have a range of tolerance, such that the workpiece cannot be precisely positioned. Furthermore, when the positioning width of the workpiece is narrow or the shape of the workpiece is unusual, the two approaching switches
105
cannot be used simultaneously. This reduces the precision of positioning of the workpiece. Moreover, the approaching switches
105
are relatively expensive.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a positioning apparatus which can precisely position a workpiece having a narrow positioning width.
Another object of the present invention is to provide a positioning apparatus which can precisely position a workpiece having an unusual shape.
A further object of the present invention is to provide a positioning apparatus which is inexpensive.
In order to achieve the above-mentioned objects, a positioning apparatus for a workpiece in accordance with the present invention comprises a base, a positioning block and a circuit. The base comprises a shoulder defining a screw hole therethrough. The positioning block comprises an upper block, and a lower block having a front surface. The upper block defines a shoulder hole, for extension of a bolt therethrough to engage in the screw hole of the base. The bolt thereby secures the positioning block on the shoulder of the base. Layers of insulator are compressed between the base and the positioning block, and between the base and the bolt. The layers insulate the base and the positioning block from each other. The circuit comprises a power source and a relay. The power source provides direct current voltage. The relay comprises a coil electrically connected between the power source and the positioning block, and a normal-open switch electrically connected between the power source and a manipulator which acts on the workpiece. When the workpiece contacts the front surface of the positioning block, the coil is electrified and the normal-open switch closes. The interface of the manipulator turns to high level. The manipulator starts its next programmed motion, leaving the workpiece in its correct position.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 4357821 (1982-11-01), Fowler
patent: 4706491 (1987-11-01), Sartorio
patent: 5844146 (1998-12-01), Murray et al.
patent: 5865056 (1999-02-01), Nagakura
patent: 6269677 (2001-08-01), Torvinen et al.

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