GB2077656A

GB2077656A - Compass sawing machine

Info

Publication number: GB2077656A
Application number: GB8116162A
Authority: GB
Original assignee: Metabowerke GmbH and Co
Current assignee: Metabowerke GmbH and Co
Priority date: 1980-06-14
Filing date: 1981-05-27
Publication date: 1981-12-23
Also published as: DE3022437A1; FR2484319B3; FR2484319A1

Abstract

A compass sawing machine has a saw blade (7) fixed to one end of a lifting rod (2) and capable of performing an oscillating cutting movement and a reciprocating movement in the cutting plane which is superimposed on the oscillating movement forming the feed movement for increasing the cutting capacity. The back (8) of the saw blade (7) is supported by a guide in the form of a roller (9) and the part of the back (8) of the saw blade (7) which cooperates with the guide roller (9) is at such a feed angle to the longitudinal axis (6) of the lifting rod (2) that during the cutting stroke the saw blade effects the reciprocating movement in the cutting direction and during the return stroke the saw blade is raised from the cutting point. The guide roller (9) is mounted in an inflexibly rigid manner on the casing (1) of the machine. <IMAGE>

Description

SPECIFICATION Compass sawing machine This invention relates to a compass sawing machine in which the saw blade is fixed to one end of a lifting rod and which performs an oscillating cutting movement and a recipro cating movement in the cutting plane which is superimposed on the oscillating movement forming the feed movement for increasing the 'cutting capacity, the back of the saw blade being supported by a guide.

In the case of compass sawing machines known e.g. from German Patent Specifica tions Nos. 1,279,923 and 2,303,532, the guide takes the form of a roller bearing, by means of a mechanical gear, on the back of the saw blade and performing a reciprocating movement in the cutting plane. The mechani cal drive for the reciprocating movement of the guide roller is complicated and fault-prone and undesirably increases the constructional weight and volume of the machines.

German Patent Specification No. 878,270 discloses arranging the saw blade teeth at an angle to its lifting axis in order in this way to improve the cutting power. However, as a result of the sloping saw blade back it can buckle on the material being cut, so that there is a risk of the saw blade breaking.

In connection with a band saw blade, it is known from German Offenlegungsschrift No.

2,748,822 to construct its back in a stepped manner to improve the cutting characteristics and facilitate the feed.

The present invention aims to provide a compass saw of the aforementioned type which can be manufactured particularly inex pensively and with which a good cutting power can be achieved with a limited feeding power.

According to the invention, there is pro vided a compass sawing machine having a saw blade fixed to one end of a lifting rod and capable of performing an oscillating cutting movement and a reciprocating movement in the cutting plane which is superimposed on the oscillating movement forming the feed movement for increasing the cutting capacity, the back of the saw blade being supported by a guide, wherein the part of the back of the saw blade cooperating with the guide is at such a feed angle to the longitudinal axis of the lifting rod that during the cutting stroke the saw blade effects the reciprocating move ment in the cutting direction and during the return stroke the saw blade is raised from the cutting point, the guide being arranged in an inflexibly rigid manner on the casing of the compass sawing machine.

As a result of this construction of the saw blade back with its associated guide, no addi tional mechanical expenditure with bearings and transmissions is required for obtaining the feed movement of the saw blade. The saw blade and guide, which are the parts particularly exposed to wear, can be replaced with little effort, the costs of the spares being low.

According to the invention, the feed angle is approximately between 2 to 8 , the angle being smallest with metal saws, larger with saw blades for hardwood and largest for saw blades for softwood, plastics, etc. Thus, without additional construction expenditure, it is possible to adapt to the different materials to be worked. In addition, the feed angle can be smaller with a close pitch than with a wider pitch of the saw blade in order to achieve optimum cutting conditions and reliably ensure removal of sawdust.

According to a preferred embodirnent of the invention, the lifting rod is guided at its upper end with a limited clearance and a lower guide bearing is provided in which the lifting rod is guided at right angles to the sawing direction and is received with clearance in the cutting plane to permit the reciprocating movement.

In order to be able to carry out cuts at a limited distance from vertical walls or the like or circular cuts in corners, it is particularly advantageous for the saw blade guide, the saw blade itself, the lifting rod and at least the lower guide bearing to be arranged so as to be able to rotate approximately about the longitudinal axis of the lifting rod. It is constructionally particularly simple for this purpose for the guide and at least the lower guide bearing to be located in a rotatably held bearing sleeve.

In the case of a compass sawing machine with a handle or grip arranged on the casing facing the saw blade, it can be particularly advantageous for controlling the sawing direction for the upper end of the lifting rod to be guided in the handle which is rotatably positioned in the casing for rotating the saw blade.

The invention will now be further described, by way of example, with reference to the drawings, in which: Figure 1 is a partly-sectioned side elevation of one embodiment of a compass sawing machine according to the invention; Figure 2 is a cross-section through the lifting rod just above the lower guide bearing taken along the line Il-Il of Fig. 1; and Figure 3 is a cross-section corresponding to Fig. 2 of another embodiment.

In the case of the compass sawing machine shown in Fig. 1, a lifting rod 2 is displaceably guided in a casing 1 in an upper guide bearing 3 and a lower guide bearing 4 via a crank drive 5 approximately in the direction of the longitudinal axis 6 of the lifting rod 2.

A saw blade 7 is interchangeably fixed to the lower end of the lifting rod 2 in an extension of the longitudinal axis 6. The back 8 of the saw blade 7 bears on the guide 9 which, in the form of a roller, has an ail-round recess 10, so that the saw blade 7 also has a certain lateral guidance.

The lifting rod 2 is guided in only one plane in the lower guide bearing 4 and is able to perform a reciprocating movement in the plane of the saw blade 7.

To improve the guidance, the lifting rod 2 can have a hexagonal cross-section, in the manner shown in Fig. 3. In this case, two facing guide surfaces 11 are guided in formlocked manner in the lower guide bearing 4, so that they can perform both the lifting and the reciprocating movement of the lifting rod 2.

To obtain the reciprocating movement, the back 8 of the saw blade 7 is chamfered at a feed angle 12 in such a way that during the cutting stroke, the saw blade 7 effects the reciprocating movement in the cutting direction and during the return stroke the saw blade 7 is raised from the cutting point. The feed angle 12 is between approximately 2 and 8 , preferably approximately 5 .

In order to be able to saw in different directions, the lifting rod 2 with the lower guide bearing 4 and the guide 9 with the saw blade 7 can be arranged so as to rotate about the longitudinal axis 6.

Claims

1 A compass sawing machine having a saw blade fixed to one end of a lifting rod and capable of performing an oscillating cutting movement and a reciprocating movement in the cutting plane which is superimposed on the oscillating movement forming the feed movement for increasing the cutting capacity, the back of the saw blade being supported by a guide, wherein the part of the back of the saw blade cooperating with the guide is at such a feed angle to the longitudinal axis of the lifting rod that during the cutting stroke the saw blade effects the reciprocating movement in the cutting direction and during the return stroke the saw blade is raised from the cutting point, the guide being arranged in an inflexibly rigid manner on the casing of the compass sawing machine.

2. A compass sawing machine according to claim 1, wherein the guide comprises a roller.

3. A compass sawing machine according to claim 1 or claim 2, wherein the feed angle is between approximately 2 and 8 .

4. A compass sawing machine according to claim 3, wherein the feed angle is approximately 5t.

5. A compass sawing machine according to any one of claims 1 to 3, wherein, with a close pitch, the feed angle is smaller than with a wide pitch of the saw blade.

6. A compass sawing machine according to any preceding claim, wherein the lifting rod is guided at its upper end with a limited clearance and a lower guide bearing is provided in which the lifting rod is guided at right angles to the sawing direction and is received with clearance in the cutting plane to permit the reciprocating movement.

7. A compass sawing machine according to claim 6, wherein the guide for the saw blade, together with said saw blade, the lifting rod and the lower guide bearing, is arranged so as to be able to rotate approximately about the longitudinal axis of the lifting rod.

8. A compass sawing machine according to claim 7, wherein the guide and at least the lower guide bearing are provided in a rotate; bly held bearing sleeve.

9. A compass sawing machine according to claim 7 or claim 8, wherein the lifting rod has at least one lateral guiding surface and the lower guide bearing has an opposite surface associated with said guiding surface and a guiding surface parallel thereto.

10. A compass sawing machine according to claim 9, wherein the lifting rod has a rectangular or hexagonal cross-section.

11. A compass sawing machine according to any preceding claim, wherein the machine has a casing provided with a handle facing the saw blade, wherein the upper end of the lifting rod is guided in the handle and wherein said handle is rotatably positioned in the casing for rotating the saw blade.

12. A compass sawing machine according to any preceding claim, wherein the back of the saw blade is engaged on the guide by means of the tension of a spring.

13. A compass sawing machine substantially as described herein with reference to the drawings.