GB2155373A - Automatic grinder for chain saw gouge chains - Google Patents

Abstract

Grinder comprising a frame (1) with a table and columns (3) supporting the grinding head (7) characterised by a chain holding disc (29) driven continuously by an electric motor (30) through a friction coupling (31), on which disc the chain is mounted in a tensioned state, circulating in front of the grinder head (7) and a gouge detector (32) and a releaseable abutment (36) for stopping the gouges in the grinding position. The friction drive urges the chain against the stop so that the position of the gouge in the grinding position is accurately maintained. <IMAGE>

Description

SPECIFICATION Gouge chain grinder with an automatic device for detecting, advancing and stopping the chain The invention relates to a grinder comprising an assembly for presenting, detecting, advancing and stopping the chain in front of the grinding head.

The main application relates to gouge chains, particularly the chains of chain saws.

Semi-automatic grinders are available in which the chain is advanced by means of a jack associated with a ratchet. Pushed by the ratchet, the chain advances linearly, step by step, in front of a grinding head which carries out the actual grinding operation. The jack travel is regulated for one feed step equal to an interval between two successive gouges on the same side: left or right.

According to improved constructions, the stepby-step advancing movements of the jack and consequently of the chain are a function of the downwards and upwards movements of the grinder before and after each grinding.

These intermittent driving movements do not guarantee the desired accuracy or regularity of grinding. Futhermore, the speed and precision of positioning are limited as is also the rate of grinding due to the time wasted due to return and change of the direction of the alternating movement.

The object of the present invention is to remedy these drawbacks by proposing an automatic grinder comprising a device for presenting, advancing and stopping the chain and employing a rotary support and a rotary drive to move the chain in front of the grinding head.

For improving accuracy and for maintenance in position during the grinding sequence, the chain carrier is forced under constant pressure against a ratchet stop by a continuous rotary drive with a friction clutch. The device for detecting the first gouge makes it possible to propose integral automation.

Presentation on a rotatingly driven circular chain carrier makes it possible, without interrupting the working sequence, to grind the second series of gouges virtually continuously after a simple tilting of the grinding head.

Furthermore, the grinder according to the invention makes it possible to achieve perfect grinding by applying a first movement for a primary grind followed by a finishing grind.

The technical characteristics and other advantages of the present invention are set out in the ensuing description which is given by way of nonlimitative example and in which reference is made to the appended drawings, in which: Figure 1 is a general perspective view of the automatic grinder comprising the presenting and advancing device according to the invention; Figure 2 is a general elevational view of the presenting and advancing device; Figure 3 is a detail of the upper part of the presenting and advancing device; Figure 4 is a detail of the detecting unit; Figure 5 shows on a larger scale the grinder head and its mechanism for controlling pivoting and grinding movements.

By virtue of the association of in particular the mechanical technical means described hereinafter, the according to the invention might be associated with a programmed sequence automatic plant to provide for entirely automatic operation whatever the length of the chain or the type of gouge chains to be ground.

The grinder according to the invention is supported by a frame 1 of the type which, for example, has a bottom table 2 and columns such as 3. A support or grinder carrying arm 4 is mounted for translatory movement along the columns 3 and can be stopped in a regulable position. The support 4 has one end shaped like a sleeve 5 for holding the pivoting axis 6 of the grinding head 7. This axis is caused to pivot by an electric motor 8 disposed at the top end.

A detection and stop device 9 which operates in relation to angular movements of the grinding head is mounted at the bottom head of the sleeve 5. This device for detecting angular movements of the grinding head is formed, for example, by a fixed mount 10 carrying limit switches such as 11 and a movable mount 12 acting on the switches 11.

This detection of the end of travel provides for limitation of the angular movements in the extreme working positions and marking of the angular position.

The actual grinding head 7 comprises a motor block 13 mounted in an inclined position at the end of the pivoting arbor 6 through the intermediary of a support 14 having a sloping front to which there is attached in flexible manner by an intermediate piece 15 a mount 16 of the collar type. The motor 17 drives an abrasive wheel 18 of the grinding wheel type protected by a removable and translucent cover 19.

The grinding head 7 is furthermore driven with an oscillating grinding movement which makes it possible to grind each gouge twice in succession.

Indeed, the accuracy and the cleanliness of grinding call for each gouge to be ground in at least two passes. The progressive grind which is thus achieved proves to be of a very high quality: it can be classified as a primary rough grind in which the grinding head penetrates halfway, followed by a full-depth finish grind.

To do this, the motor carrier assembly is mounted to reciprocate between a low position and a high position vie an articulation 20 provided between the support 14 and the collar 16.

The articulation 20 is provided, for example, simply in the form of a spindle 21 parallel with the body of the motor block 13 traversing a lever 22 constituting a lateral extension of the collar 16 towards a reciprocating mechanism 23.

The reciprocating mechanism 23 comprises a cam 24 of suitable profile operated by an electric motor 25. Contact of the cam 24 with the roller 26 provided laterally at the end of the lever 22 produces oscillating rise and fall movements of the motor 17.

To perform two grinding movements with an intermediate rise, a profile will be adopted which has two bosses separated by one point. The motor 25 is mounted to be rigid with the support 14 which has the sloping front. The tilting action of the grinding head 7 results from contact of the cam 24 on the lever 22. Two microswitches (not shown) deliver end of travel or limit signals which correspond to the high and low positions.

The device for advancing and detecting the chain to be ground will be examined hereinafter. The chain to be ground 27 is mounted on a rotary drive support assembly 28 constituted by a chain carrying disc 29 having two parallel flanges capable of being brought towards each other. This conformation makes it possible to keep the chain straight by introducing between the two flanges the small lugs on the links. The chain is maintained taut by a tensioning device having an eccentric member and having at the end a return pulley.

The chain carrying disc 29 is caused to rotate by an electric motor 30 which is linked kinematically to the chain carrying disc by a friction coupling 31.

As will emerge from the following development, the chain must be taut and remain taut to guarantee satisfactory immobilisation of the link during the course of grinding.

On either side of the chain carrying disc 29 are means which fulfil on the one hand the function of detecting and on the other the function of immobilising the chain.

Recognition of the gouges and their parity is carried out by a retractable detector 32 consisting of two microswitches, left 33 and right 34, with a tilting claw and ending, for example, in a roller such as 35, following the top lateral edges of the chain and changing condition at the moment of and throughout the duration of passage of the gouge at a right-angle to the switch. The change of state of one or other of the detecting switches is exploited to operate and supervise the automatic functioning of the grinder according to the invention.

The gouges are immobilised by association of the rotary friction drive with the stopping of a releasable abutment 36, operated by the detection, for example a click stop which is positioned in front of the front edge of the gouge and which enters into bearing contact with it.

As indicated, the releasable stop is preferably in the form of a ratchet stop 37, for example through a dog or rod 38 mounted to rock about a spindle 39 parallel with that driving the chain carrier disc 29 which is urged to form stop and release movements by an electromagnetic reciprocating means, for example one which has a plunger core 40 mounted to be restored by elastic means towards a high position.

The movable element of the ratchet is mounted to tilt towards the rear until it makes contact with a microswitch 41.

The support 42 of the ratchet is designed to be adjustable and move farther towards or away from the chain and is operated by a programmed automastic device which provides for functional co-ordination of the whole.

The various phases of operation of the automatic grinder according to the invention will be described hereinafter.

The chain to be ground is placed in position on the chain carrying disc 29 in that the small lugs are inserted into the adjustable gap which exists between the two discs. The chain is tensioned by means of the tensioning device which has an eccentric member.

The previously retracted detection device is tilted into the operative position on either side of the chain. The two detector switches are adjusted to the width of the chain.

The initial settings are made manually: angular deflection, depth of penetration Of course, when there are a series of chains of the same type or even the same characteristics, the adjustments remain the same. It is possible likewise to store in a memory the total number of gouges to be ground.

The grinder is then ready for the working sequence to be carried out automatically.

The grinding head is presented according to the grinding sub-sequence: right-hand gouges or lefthand gouges, determined by the inner programme.

Once it has been started, the motor drives the chain over the chain carrying disc 29. Previously the characteristics of the chain to be ground, particularly the number of gouges, will have been committed to the memory.

When the starter switch, automatic cycle, is op erated, the detector starts to function. Detection of the first gouge produces a tilting of the ratchet 37, the rod of which drops into the free space between two gouges.

Indeed, the time constant between detection, that is to say passage of the gouge into the detector and lowering of the ratchet, is less that the time it takes for the gouge to travel between the outlet from the detector and its being presented to the ratchet. Correlatively, the gouge must have crossed the end of the rod before it drops.

The chain continues to turn until the rear edge of the gouge strikes. the end of the rod 38 of the ratchet.

The driving effect pushes to rod 38 into its return and stop position in which it operates the microswitch 41. This pulse gives the order for the grinder to drop.

The driving motor continues to turn, operating the friction coupling which engenders and maintains a constant mechanical force urging the chain towards its usefully stopped position to maintain the chain under tension throughout the grinding period.

The grinding cycle takes place with a double grinding movement: primary grinding of reduced penetration and full depth finish grinding, by the effect of the cam and the reciprocating movement of the grinding head.

The renewed rise of the grinder at the end of the grinding operation actuates the top limit switch which releases a reversal of rotation of the motor for a fraction of a second in order to free the ratchet. The sequence is continued by the same grinding movements and so on until all the gouges of like parity have been completely ground. The counter or the memory storing the number of gouges to be ground triggers angular reversal of the grinding head.

In the initial adjustments, the bottom point of grinding(full penetration) is given and regulated by the displacement of the assembly along the columns 3.

The invention is open to simple modification and direct alternative embodiments, and also to substitutions by equivalent means and materials without thereby departing from the scope of the present protection.

Claims (9)

1. Automatic grinder for gouge chains in particular for chains of chain saw, comprising a frame (1) with a table and columns (3), and support (4) mounted for translatory movement along the columns and a pivoting grinding head (7), characterised in that it is composed of a chain carrying disc (29) caused to rotate continuously by an electric motor (30) through a friction coupling (31), a disc on which the chain is held taut by a tensioning device with an eccentric member and on which it circulates in front of the grinding head (7) between a gouge detector (32) and a releaseable stop (36) which locks the gouges in the grinding position, maintenance in this position resulting from the continuous drive through the friction coupling and in that the grinding head is capable of performing oscillating tilting movements.

2. Grinder according to Claim 1, characterised in that the detector (32) is retractable constituted by two microswitches, left (33) and riqht (34) having a tilting lug, terminated by a small wheel (35) capable of being retracted or of projecting when a gouge is passing.

3. Grinder according to Claim 1 characterised in that the releaseable stop (36) is a ratchet (37) in the form of a rod (38) mounted to tilt about a spindle (39) parellel with that which drives the chain carrying disc which is urged to perform stopping and releasing movements by a electromagnetic reciprocating means which is biased into the up position by a flexible restoring means.

4. Grinder according to Claims 1 and 3, characterised in that the releaseable stop (36) is capable of performing longitudinal movements between an advanced position and a withdrawn position in which it operates a contact.

5. Grinder according to Claim 1, characterised in that the grinding head (7) comprises a mechanism for repetitive tilting movements between a low grinding position and a high retracted position.

6. Grinder according to Claim 5, characterised in that the tilting mechanism is a profiled cam (24) operated by an electric motor (25) acting on a roller (26) disposed at the end of a lever (22) as an extension of the mount, enclosing the body of the grinding motor, the motor-lever assembly being mounted on a transverse rotary axis.

7. Grinder according to Claims 1, 5 and 6 taken jointly, characterised in that the body of the grinding motor is connected in flexible manner to its pivoting axis.

8. Grinder according to Claims 1 and 7, characterised in that the end of the pivoting axis of the body of the grinding motor is rigid with a mount which co-operates with a fixed coaxial mount bearing end-of-travel contacts for detecting the angular extreme positions.

9. Automatic grinder for gouge claims constructed and arranged substantially as herein described with reference to the accompanying drawings.