WO2013168082A1

WO2013168082A1 - Positional reference device

Info

Publication number: WO2013168082A1
Application number: PCT/IB2013/053647
Authority: WO
Inventors: Argentin ANDREA
Original assignee: Andrea Argentin
Priority date: 2012-05-08
Filing date: 2013-05-07
Publication date: 2013-11-14
Also published as: ITTV20120072A1

Abstract

To improve the positioning of a workpiece a positional reference device is presented associable to a machine (PR) which has a tool (P) movable for working a workpiece (SH), characterized by comprising - an abutment portion (12) for the piece adapted to define a predetermined position of the workpiece relative to the tool; - means (50, 52, 54, 12, SH) adapted to vary an output quantity as a function of the contact condition between the workpiece and the abutment portion.

Description

POSITIONAL REFERENCE DEVICE

The invention relates to a positional reference device, to the machine mounting it and to a control method.

Machines are known for bending metal sheets, here chosen as descriptive example, as the press-bending machines illustrated in U.S. 6,732,559, WO 98/46378, WO201 1039697 and EP1731237.

These machines usually comprise a cross-member or fixed lower table with a bending die, and an upper cross-member, movable relative to the lower cross-member and equipped with a punch corresponding to the die. A bridge serves to support the upper cross-member while thanks to power actuating means the cross-members can approach to one another to obtain the bending action.

The workpiece is usually placed manually on the die and then bent. Special stroke references or abutments are used, placed behind the cross-bars against which the operator abuts a workpiece's edge. In this way, the point is indirectly established on which the punch descends.

The problem of this system is the uncertainty of the contact between the workpiece and the abutments, which results in machining errors. The operator is unable to see directly if the piece is properly in contact on an abutment, and trusts his placement counting on the fact that the piece does not move further. In reality, imperfections in shape, chips, carelessness or improper placement of the piece cause a failure to abutting on the references, and the piece is bent poorly.

So it is desirable to improve the state of the art, and in particular to solve the aforesaid problem.

A positional reference device is proposed as in the appended claims. It is associable to a machine (even pre-existent) which has a tool movable for working a workpiece, characterized by comprising

- an abutment portion or member for the workpiece adapted to define a predetermined position of the workpiece relative to the tool;

- means adapted to vary an output quantity or variable as a function of the contact condition between the workpiece and the abutment portion (or member).

The output quantity can be any variable (mechanical, electrical, in general physical and measurable) that can be used to discriminate the contact condition between workpiece and abutment (or member) portion. As preferred variants we cite:

- an electrical signal;

- the position or orientation of a mechanical element or piece (e.g. the slider of a potentiometer or the position or state of an electrical or mechanical switch as a valve),

- a flow of air,

- a beam of light;

- in general, an electromagnetic wave.

In the device, or externally to it, the monitored quantity, advantageously the electric signal because it is easy to implement, can serve to determine the state of a warning light (e.g. an LED or a flashing light or a light source in general) and/or an acoustic alarm (e.g. buzzer or speaker), and to report or indicate to the operator the contact or not of the workpiece with one or each abutment. The alarm can be comprised in the device or can be remote, or mounted on a panel or board away from the device.

In case of electrical signal, the device can operate in reliable manner comprising simple and cheap parts. In particular it is advantageous that the device comprises an electrical mesh whose open / closed state is changeable from the contact condition between the workpiece and the abutment portion. E.g. the workpiece can, by contact with an abutment, interact with an electrical switch or with a diverter valve or flow regulator (air or liquid) by varying the state thereof or that of the flow.

By "mesh" (or loop) the meaning of electrology is intended, i.e. a network of electrical conductors whose path, all constituted by branches of the network, begins and ends in the same node. Said otherwise, a mesh is a closed path of an electrical network that starting from a node returns to the same without passing through the same branch twice, not being necessary that between two successive nodes of the mesh there is a component, being there a short circuit or an open circuit segment.

To further simplify the system and improve its reliability, the open/closed state can be changeable by the workpiece's own conductivity, i.e. the conductive mass, e.g. made of metal, or part of it - when it is present in the piece - is exploited to close an electrical circuit or mesh. Thus the condition of contact between the workpiece and the abutment portion (or element) determines automatically and without errors the variation of an electric quantity.

To make the device portable or easily integrated, it can comprise an autonomous power- supply source, e.g. a battery and/or a solar panel; to supply the alarm and/or the electrical circuits of the device.

The device can equip any pre-existent machine tool and be integrated in its structure. In particular a machine can be produced comprising

- a worktop on which to rest (preferably manually) a workpiece;

- a tool movable toward the worktop to contact and/ or work the workpiece;

- a positional reference abutment for the workpiece in the vicinity of the worktop,

characterized in that the reference abutment comprises means adapted to vary an output quantity or variable as a function of the contact condition between the workpiece and the abutment.

For said means of the machine all the variants described for the device hold, and the relative advantages extend to the machine as well.

By the device and / or its integration in the machine a method can be accomplished for the machine (e.g. a press-bending machine or a manually loadable cutter), in particular a safety method. In a machine as defined above it is possible to

- monitor the output quantity or variable, preferably during the manual loading of the workpiece on the machine, and - (i) inhibit/ allow the movement of the tool if the output quantity corresponds to a lack/ presence of contact between the (preferably manually moved) workpiece and the abutment (portion or member) .

In addition or replacement to step (i) one can

(ii) activate an audible or visible signal in the absence or presence of said contact,

(iii) send a signal (e.g. radio or infrared) to a remote unit to communicate the contact condition or not between the workpiece and the abutment (portion or element);

(iv) in the absence of said contact activate a mechanism, with which the machine can be provided, adapted to move the workpiece to bring it into contact with the abutment portion or element (e.g. through a ratchet or clamp or movable sucker, an electromagnet, a conveyor belt) .

As other phases the method can integrate the means and all the variants described for the device, and the same benefits extend also to the method.

The following description relates to a preferred embodiment of the device, where reference is made to the attached drawing in which

Fig 1 shows a side view of a machine with the device on board, Fig 2 shows an axonometric view of the device.

A press-bending machine PR (fig. 1) comprises a cross-member or fixed lower table B with a bending die TL, and an upper cross member TH, movable relative to the lower cross-member and equipped with a punch P corresponding to the die. A bridge C serves to support the upper cross-member TH, and power actuating means bring the cross- members TH, TL close to one another to obtain the bending action on a piece of sheet SH.

As an end-of- travel or abutment reference there is a device 10, located behind the cross-member TL, against which the operator abuts an edge of the workpiece SH. This indirectly establishes the point of the piece SH on which the punch P falls.

Fig. 2 shows the isolated device 10. It comprises an optional element or support bracket 40, in the example in the form of a C-shaped bridge, on which is mounted a hollow block 20.

The block 20 houses a metal plate or finger or pin 12 having a protruding portion on which the piece SH can lean and/or abut against. Said projecting portion is optionally equipped with steps 14, to allow the piece having various points of abutment.

Preferably, the finger 12 is slidably inserted into the block 20, and then fixed to it.

Inside the block 20 is a battery 50 with a pole connected through a conductor 52 to the metal mass 54 of the machine PR. Through another conductor 52 the other pole is connected to finger or plate 12, so as to feed in series an LED 24, which preferably is located inside a front hole 22 of the block 20. The electrical circuit is shown schematically in fig. 2, with the components shown outside for simplicity.

From fig. 2 the operation of the device 10 can be understood.

By positioning the piece SH on the cross-member TL, the piece SH is brought into contact with the mass 54 of the machine PR. Only by touching the finger 12 the piece SH closes the circuit or mesh of Fig. 2 and let the LED 24 turn on, which can be seen by the operator. The bending operation is not allowed to start until the LED is not turned on (for each device 10 aligned on the cross-member TH), and thus the positioning of the workpiece SH is precise.

It is sufficient that the finger 12 is isolated from the rest of the metal mass. E.g. the block 20 and/or the bracket 40 can be made of electrically insulating material, or only a part of the finger 12, not in contact with the block 20, is conductive.

Claims

1. Positional reference device ( 10) associable to a machine (PR) which has a tool (P) movable for working a workpiece (SH), characterized by comprising

- an abutment portion (12) for the piece adapted to define a predetermined position of the workpiece relative to the tool;

- means (50, 52, 54, 12, SH) adapted to vary an output quantity as a function of the contact condition between the workpiece and the abutment portion.

2. Device according to claim 1, wherein the output quantity comprises an electrical signal.

3. Device according to claim 2, wherein the electrical signal is adapted to determine the state of a luminous warning device (24).

4. Device according to claim 2 or 3, wherein the electrical signal is adapted to determine the state of an acoustical warning device.

5. Device according to claim 2 or 3 or 4, comprising an electrical loop (50, 52, 54, 12, SH) whose open/ closed state is changeable from the contact condition between the workpiece (SH) and the abutment portion ( 12).

6. Device according to claim 5, wherein the open/ closed state is changeable by the workpiece' s own conductivity.

7. Device according to any one of the preceding claims, comprising an autonomous power-supply source to power supply the warning device.

8. Machine (PR) comprising

- a worktop on which to rest a workpiece (SH);

- a tool (P) movable toward the worktop to contact or work the workpiece;

- a positional reference abutment ( 12) for the piece in the vicinity of the worktop,

characterized in that the reference abutment comprises means (50, 52, 54, 12, SH) adapted to vary an output quantity as a function of the contact condition between the workpiece and the abutment.

9. Manually loadable press-bending or shearing machine comprising a device as any one of claims 1 to 7.

10. Control method for a machine (PR) which comprises

- a worktop on which to manually rest a workpiece (SH);

- a tool (P) movable towards the worktop for contacting the workpiece;

- a positional reference abutment ( 12) for the workpiece in the vicinity of the worktop, the reference abutment comprising means (50, 52, 54, 12, SH) adapted to vary an output quantity as a function of the contact condition between the workpiece and the abutment,

characterized by

- monitoring the output quantity and

- inhibiting the movement of the tool if the output quantity corresponds to a lack of contact between the manually moved workpiece and the abutment. .