GB2343401A

GB2343401A - Device by tool for removing burrs

Info

Publication number: GB2343401A
Application number: GB9924947A
Authority: GB
Inventors: Asbjorn Mortensen
Original assignee: TRITEC AS
Current assignee: TRITEC AS
Priority date: 1998-11-09
Filing date: 1999-10-22
Publication date: 2000-05-10
Anticipated expiration: 2019-10-22
Also published as: NO308729B1; NO985208D0; DE19953759A1; DE19953759B4; FR2785560A1; GB9924947D0; GB2343401B; NO985208L

Abstract

The invention relates to a device by a tool adapted to remove burrs from an object of e.g. moulded plastic. The object of the invention is to provide a tool which is passed along the burr by means of a robot during the removal of the burr, and which is capable of handling possible differences in the course of the burr from object to object. This is realized in the way that the tool comprises a knife (1) for cutting away said burrs and a holding device (7, 5, 2) for the knife (1), said holding device (7, 5, 2) being arranged so that the knife (1) is forcedly directed against said burrs as the tool is fed forward along a predetermined course along the object by means of a robot.

Description

1 2343401 DEVICE BY TOOL FOR REMOVING BURRS The invention relates to a

device adapted to the removal of burrs from an object of e.g. blow-moulded plastic.

The objects of e.g. blow-moulded plastic are normally manu- factured by the use of a two-part moulding tool. A heated plastic cylinder is placed in the mould parts, before they are assembled, and is blown up until the plastic presses against the internal sides of the mould parts. During the blow-up some of the plastic is pressed out into the opening between the mould parts. Thus, undesirable burrs are formed on the object. After the blow-up the mould part is removed, and the object is put aside for cooling and subsequent finishing work. The burrs are removed in the finishing of the object.

is So far, it has been the most common for burrs to be removed by a knife passed by hand along the object. Such work is uncomfortable since the object still has a temperature of 80 100 OC during the cutting, and besides, it is strenuous. There is also known a tool for the removal of burrs, whereby 2 the object is placed in the tool and the burrs are removed by means of a clipping device of the tool. The drawbacks of this is that the tool has to be made big to accommodate the object. Further great forces are required during the clipping of the burr since the object must be completely cooled before it is placed in the tool, and the clipping edge often turns out raqqed.

The most suitable is that the burr is removed as soon as possible after the object has been taken out of the mould parts and is still hot. This is probably the main reason why robots are not used for guiding such tools for removing burrs. Plastic has a relatively great shrinkage in cooling, and moreover, the shrinkage depends on the thickness of the plastic. Thereby possible differences for example in temperature dur- is ing the removal of the burr or in the thickness of the plastic after the blowing up, varying from object to object, will make it very difficult to pre-program the robot's path of advancement, so that the tool may at all times remove burrs of varying courses.

The main object of the present invention is to provide a device by a tool adapted to remove burrs from an object of the above type,_ whereby the tool is passed along the burr by means of a robot, and whereby the tool is capable of handling possible differences in the course of the burrs from object to object. As appears from the characterizing part of the present independent claim, this is realized in the way that the tool comprises a knife for cutting the burrs, and a holding device for the knife, the holding device being arranged so that the knife is forcedly moved forward against said burrs when the tool is directed by means of a robot along a predetermined course along the object. Thereby the robot may 3 be pre-programmed so that the knife is kept in a normal position during its advancement along the burr. The holding device will forcedly direc t the knife to the correct position along the burr if the burr has a deviating course, so that in principle the knife gets the same course as if the knife was moved forward manually. Other advantageous features of the invention will appear from the other claims and the specification.

In the following part of the specif ication and with reference to the set of figures, an embodiment of the invention will be explained, Fig. 1 showing a schematic side view of the tool, in which one half of an upper housing of the tool has been left out, so that the configuration of the tool is better shown; Fig. 2 showing a schematic view of a longitudinal section through the tool; and Fig. 3 showing a schematic view of another longitudinal section through the tool during the cutting of burrs on a blowmoulded object.

The present tool for the removal of burrs from an object of e.g. moulded plastic, comprises a knife 1 for cutting off the burr and a holding device 7, 5, 2 for the knife 1. The holding device, formed by an upper housing 7, an intermediate holder 5 and a lower rotor 2, is arranged so that the knife 1 is forcedly advanced against the burr when the tool is passed by means of a robot along a predetermined path along the object. The tool is placed in a not shown robot by means of the housing 7.

4 The knife 1 is placed in a slot in the rotor 2 and is secured in a suitable manner, e.g. by two locking pins 3. The rotor 2 is rotatably supported in the holder 5, so that the knife 1 may rotate about the longitudinal axis of the tool. This is done by means of a bore extending through the holder 5 with associated bearings 4. The bore is formed in the longitudinal direction of the tool and is equipped with e.g. ball bearings 4 at the upper and lower ends of the bore. The knife 1 is positioned in the rotor 2 with the cutting edge la behind the axis of rotation of the rotor 2, seen in the tool feeding direction. Further, the rotor 2 is provided with a pin 8 and the housing 7 with two stop dogs 9 for the pin 8. The pin 8 and the stop dogs 9 are adapted so that the rotation of the rotor 2 within the holder 5 is limited. The pin 8 is. secured is at the upper end of the rotor 2 and so that it projects above the bore of the holder 5. The stop dogs 9 are secured to the housing 7 on either side of the pin 8 and at a distance allowing the rotor 2 to rotate a few degrees towards either side of a normal position, before the pin 6 is stopped by the respective stop dog. The allowed rotation of the rotor 2 may be varied by the use of adjustable stop dogs 9. The rotor 2 is retained in, possibly pulled back into, said normal position by means of a spring 10 which is secured to the pin 8 and the housing 7.

The holder S is suspended pendulumlike within the housing 7 by means of two axle journals 6 extending between and into the holder 5 and the housing 7. The axle journals 6 are placed with their longitudinal axes in the tool feeding direction, so that the knife 1 may swing out sideways to both sides from said feeding direction. Besides, the holder 5 has means 11, 12, 13, 14 arranged thereto and so that the holder 5 is forcedly guided into its normal position within the housing 7 if the holder 5 is swung out of its normal position during the cutting of the burr. The means for forcedly guiding the holder 5 into its normal position within the housing 7 are formed by two springs 11 extending parallel to the longitudinal direction of the tool. The respective spring is brought into a bore formed in an upper flange 15 of the holder 5 parallel to the longitudinal axis of the tool, and has a lower adjustable dog 12 arranged thereto with an associated ball 13 and an upper tightening screw 14. The bores for the springs 11 are positioned so that a longitudinal section of the tool through the bore is normal to a longitudinal section of the bore through the axle journals 6. The dog 12 with the pertaining ball 13 is placed in a bore formed in a lower flange 16 of the housing 7, and the flange faces in- wards towards the holder 5. The spring force of the spring 11, forcedly guiding the holder 5 into its normal position within the housing 7, is adjusted by means of the tightening screw 14. The tightening screw 14 is placed in a suitable manner in the bore at the upper end of the spring 11. It should also be mentioned that the pin 8 is preferably placed close to the periphery of the rotor 2 in the above mentioned longitudinal section of the tool through the axle journals 6.

Thus, the present tool enables the robot to be programmed to follow a predetermined course along the object, so that the 2S burr may be cut as shown in Fig. 3. The burr formed in the opening between the parts of the moulding tool is fairly thin, and it is in this area that the cutting is to take place. Because of the cutting edge la being positioned behind the axis of rotation of the rotor and the rotor 2 being pro vided with means 8, 9, 10 for forced guiding, the knife 1 will be directed to follow the burr along the object. If cut ting is attempted outside the burr and into the object, the 6 cutting resistance against the knife 1 is increased. This results in the holder 5 being swung out from its normal position about the axle journals 6, so that the knife 1 instead follows the burr during its advancement along the object.

7

Claims

C L A I M S

1. A device by tool adapted for removing burrs from an object of e.g. moulded plastic, c h a r a c t e r i z e d i n that the tool comprises a knife (1) for cutting said burrs and a holding device (7, 5, 2) for the knife (1), said holding device (7, 5, 2) being arranged so that the knife (1) is forcedly directed against said burrs when the tool is advanced by means of a robot along a predetermined course along the object.

2. A device according to claim 1, c h a r a c t e r i z e d i n that the holding device comprises an upper housing (7), an intermediate holder (5) and a lower rotor (2) for the knife (1), said rotor (2) being suspended with limited rotatability in the holder (5) so that the knife (1) can rotate 3.5 by a limited angle of rotation about the longitudinal axis of the tool.

3. A device according to claim 2, c h a r a c t e r i z e d i n that the rotor (2) is rotatably supported in the holder (5) by means of a bore, extending through the holder (5), and associated bearings (4), the bore being formed in the longitudinal direction of the tool.

4. A device according to any one of the preceding claims, c h a r a c t e r i z e d i n that the tool comprises means (8, 9, 10) for forcedly directing the rotation of the rotor (2), consisting of a pin (8) secured to the rotor (2) and projecting above the bore of the holder (5), two preferably adjustable stop dogs (9) secured to the housing (7) and fac- 8 ing inwards towards the pin (8), and a spring (10) secured to and spanning between the pin (8) and the housing (7).

5. A device according to any one of the preceding claims, c h a r a c t e r i z e d i n that the holder (5) is sus- pended pendulumlike in a through bore in the housing (7) by means of two axle journals (6) extending between and into the holder (5) and the housing (7).

6. A device according to claim 5, c h a r a c t e r i z e d i n that the holder (5) has means (11, 12, 13, 14) arranged thereto and so that the holder (5) is forcedly guided into a normal position within the housing (7), and that said means (11, 12, 13, 14) for the forced guiding of the holder (5) comprise two springs (11), each extending parallel to the longitudinal axis of the knife (1), the respective spring be- ing located in a bore of an upper flange (15) of the holder (5), and having a lower adjustable dog (12) with an associated ball (13) and an upper tightening screw (14) arranged thereto.

7. A device according to any one of the preceding claims, c h a r a c t e r i z e d i n that the knife (1) is secured so in the rotor (2) that the cutting edge (1a) of the knife, seen in the-feeding direction of the tool, is behind the rotational axis of the rotor (2).