GB2429185A

GB2429185A - Saw blade

Info

Publication number: GB2429185A
Application number: GB0516973A
Authority: GB
Inventors: Paul Staite
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-18
Filing date: 2005-08-18
Publication date: 2007-02-21
Also published as: GB0516973D0; WO2007020462A1

Abstract

The blade 1 includes a leading cutting side 2 and a trailing side 3. The trailing side includes a first rear corner 4 and a second rear corner 5. First and second cutting profiles 6 and 7 are formed on the rear corners. A flat bearing surface 8 may be formed on the trailing side between the two cutting profiles. Cutting teeth 9 do not extend beyond the plane of the trailing side or beyond the plane of a right 10 or left 11 side of the blade. The first and second cutting profiles may be formed at 45 degrees to the trailing side. The blade may be used in a jigsaw provided with a guide means for the bearing surface 8.

Description

Saw blade This invention relates to a saw blade, for use particularly, but

not exclusively as a jigsaw blade.

Jigsaws are commonly used to make non-linear and intricately shaped cuts in material. In order to achieve such cuts the blades used have a short depth and a fine width, so they can be manoeuvrecl through the material without jamming. As a result of their small dimensions jigsaw blades are resilient along their length, and this flexibility can assist their passage through the material.

However, jigsaw blades suffer from a particular problem known as "run off'.

When a curve is cut into a material the resilient blade bends outwards towards its free end, and as a result the radius of the top of the cut is smaller than that at the bottom. This is mainly caused by a frictional binding between the inside flank and outside trailing edge of the blade as it is driven through the material. As the blade is turned these two parts become wedged against the material and cause the blade to bend outwards.

Jigsaw blades are mounted to a motor at their top end and are driven in a reciprocal action. It is common to provide some kind of guide means at a lower point on the blade, which has a number of purposes. Firstly, the guide means provides extra support to the blade and acts to keep it as straight as possible in use. Secondly, the guide means helps to prevent the blade from bending back when it is forced into the material to be cut. Thirdly, jigsaw blades are sometimes used at an angle to vertical, and the angle can be set by adjusting the position of the guide means back and forth. This is referred to as the pendulum action.

One known type of guide means comprises a guide roller applied to the trailing side of the blade. These guide rollers comprise a free rotating drum with a circumferential trough around their centre, in which is situated the trailing side of the blade. The drum is either fixed in position or resiliently forced against the trailing side of the blade to ensure contact. As the blade rises and falls the drum rolls back and forth, and as the blade is driven through the material the drum helps to keep the blade straight and prevents it bending back. The position of the drum can be changed in order to set a preferred cutting angle of the blade.

The present invention is intended to overcome some of the above problems.

Therefore, according to a first aspect of the present invention, a saw blade comprises a leading cutting side and a trailing side, in which the trailing side has a first rear corner and a second rear corner, in which a first cutting profile is formed on the first rear corner, and a second cutting profile is formed on the second rear corner.

The above arrangement alleviates the frictional binding which leads to "run- off'. The first or second cutting profile, whichever is on the outside of a curve being cut, actually cuts into the material if it is forced against it, which helps to prevent the blade from becoming jammed and bending outwards.

In a preferred embodiment of the invention a bearing surface can be formed on the trailing side between said first cutting profile and said second cutting profile.

The bearing surface can comprise a fiat surface which can be acted against by a guide means of a saw blade actuating device with which the saw blade can be used.

As discussed above, the most common type of guide means used with automated saw blades comprises a rotating drum provided with a circumferential trough in which the saw blade is situated. In order to allow the saw blade of the invention to work with such an arrangement the first and second cutting profiles must not cut the material of the drum.

Therefore, preferably the first cutting profile and the second cutting profile can comprise cutting teeth which do not extend beyond the plane of the trailing side. In addition, the first cutting profile and the second cutting profile can comprise cutting teeth which do not extend beyond the plane of a right and left side respectively of the saw blade.

With this arrangement the trailing side of the saw blade can be mounted in the trough of a rotating drum without cutting it.

It will be appreciated that the first and second cutting profiles can be any shapes which can cut into a subject material. These shapes can be determined by the type of material which is to be cut by the blade, for example soft wood, hard wood, or sheet metal. The various cutting profiles envisaged can be any of the known types.

It will be further appreciated that he cutting profiles could be arranged at any angle on the corners of the trailing side. However, in a preferred construction the first cutting profile and the second cutting profile can be formed at substantially 45 degrees to the trailing side.

Preferably the saw blade is a jigsaw blade, however the invention could be used with any saw blade which is used to cut curved or intricate shapes through a material.

The invention also includes an actual sawing machine provided with a jigsaw blade as described above.

Therefore, according to a second aspect of the present invention a jigsaw is provided with a saw blade comprising a leading cutting side and a trailing side, in which the trailing side comprises a first rear corner and a second rear corner, in which a first cutting profile is formed on the first rear corner, and a second cutting profile is formed on the second rear corner.

Preferably a bearing surface can be formed between said first cutting profile and said second cutting profile, and the jigsaw can be provided with guide means which acts against said bearing surface.

The first cutting profile and the second cutting profile can comprise cutting teeth which do not extend beyond the plane of the trailing side, and which do not extend beyond the plane of a right and left side respectively of the saw blade. The guide means can comprise a roller means comprising a rotating drum provided with a circumferential trough in which the saw blade can be situated.

The invention can be performed in various ways but two embodiments will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a side view of a saw blade according to the first aspect of the present invention; Figure 2 is a rear view of the saw blade as shown in Figure 1; Figure 3 is a rear perspective view of the saw blade as shown in Figure 1; and, Figure 4 is a part perspective view of a jigsaw according to the second aspect of the present invention.

As shown in Figure 1, a saw blade, in the form of jigsaw blade 1, comprises a leading cutting side 2 and a trailing side 3, in which the trailing side 3 comprises a first rear corner 4 and a second rear corner 5, in which a first cutting profile 6 is formed on the first rear corner 4, and a second cutting profile 7 is formed on the second rear corner 5.

Between the two cutting profiles 6 and 7, is a flat bearing surface 8, and as is clear from Figures 1 and 2, the first cutting profile 6 and the second cutting profile 7 comprise cutting teeth 9 which do not extend beyond the plane of the trailing side 3, and which do not extend beyond the plane of a right 10 and a left 11 side respectively of the blade 1. The cutting profiles 6 and 7 are formed at 45 degrees to the trailing side 3.

In other respects the jigsaw blade 1 is like a known jigsaw blade, and it has a leading cutting profile 12 formed in the leading cutting side 2, and it has a mounting section 13, adapted to fit into a jigsaw machine. The jigsaw blade 1 is made from metal and has a short depth A-A and a narrow width B-B, so it can be used to cut curved or intricate shapes in a subject material.

In use the blade 1 is mounted in a jigsaw machine, which could be a handheld or a free standing machine, and is moved up and down in a reciprocal action by the machine. The blade 1 is then driven into a subject material to be cut, either by running a hand held machine over the material, or forcing the material against the blade 1 in a free standing machine.

When the blade 1 is driven through a curved path (or when the material is moved through a curved path about the blade 1) the blade 1 suffers less frictional binding between whichever side 10 or 11 is on the inside of the curve and whichever rear corner 4 or 5 is on the outside of the curve, than a conventional blade. The first 6 or second 7 cutting profile, whichever is on the outside of the curve being cut, cuts into the material if it is forced against it, which helps to prevent the blade 1 from becoming jammed in the material and bending outwards.

The invention also includes a jigsaw provided with a blade as described above, and part of such an arrangement is shown in Figure 4.

In Figure 4 a jigsaw blade 40 is mounted into a jigsaw machine, only a guide means 41 of which is visible. The jigsaw machine is of a known construction and is therefore not further described here. The jigsaw blade 40 is of identical construction to jigsaw blade I as shown in Figures 1 to 3. In particular it has a trailing side 42 with a first cutting profile 43 formed on a first rear corner 44, a second cutting profile 45 formed on a second rear corner 46, and a flat bearing surface 47 formed between the cutting profiles 43 and 45. The teeth 48 of the cutting profiles 43 and 45 do not extend beyond the plane of the trailing side 42, and do not extend beyond the plane of a right (not visible) and left 49 side respectively of the saw blade 1.

The guide means 41 comprises a roller means 50 comprising a rotating drum 51 provided with a circumferential trough 52. The drum 51 is mounted on two arms 53 and 54, which can be moved back and forth in a pendulum action in order to support the blade 40 at a preferred angle.

The trailing side 42 of the blade 40 is disposed in the trough 52, and is thereby held in position by the guide means. The trough 52 is deeper than the depth- wise extent of the first and second cutting profiles 43 and 45 on the blade 1, such that parts of the right (not visible) and left 49 sides of the blade 1 contact the walls of the trough 52. The bearing surface 47 is in contact with the base of the trough 52.

It will be appreciated that the first cutting profile 43 and the second cutting profile 45 do not cut into the rotating drum 51 because they do not extend beyond the planes of the trailing side 42, the right (not visible) and the left 49 side.

Thus, the jigsaw blade of the invention can be used with known guide means without causing damage.

The above described embodiments can be altered without departing from the scope of the invention. In particular, in one alternative embodiment (not shown) a saw blade according to the invention is formed as an ordinary saw blade for a hand- driven saw with a handle at one, or either end. In another alternative embodiment (not shown) a saw blade according to the invention is formed as a hack- saw blade.

The above described embodiments suffer from one drawback, which is that the Cut made by the blade can be widened if the first or second cutting profiles cut into the material on the outside of the curve. The tighter the curve the wider the cut may be. In order to manage this problem the first and second cutting profiles can be arranged at deeper or shallower angles than 45 degrees as shown above. Therefore, in other alternative embodiments (not shown) the first and second rear cutting profiles are formed at other angles than 45 degrees, and are formed at angles ranging from 1 degrees to 89 degrees to the trailing side.

Thus a saw blade is provided which greatly reduces the occurrence of "runoff'.

Claims

Claims.

1. A saw blade comprising a leading cutting side and a trailing side, in which the trailing side comprises a first rear corner and a second rear corner, in which a first cutting profile is formed on the first rear corner, and a second cutting profile is formed on the second rear corner.

2. A saw blade as claimed in Claim I in which a bearing surface is formed on said trailing side between said first cutting profile and said second cutting profile.

3. A saw blade as claimed in Claim 2 in which the first cutting profile and the second cutting profile comprise cutting teeth which do not extend beyond the plane of the trailing side.

4. A saw blade as claimed in Claim 3 in which the first cutting profile and the second cutting profile comprise cutting teeth which do not extend beyond the plane of a right and left side respectively of the saw blade.

5. A saw blade as claimed in Claim 4 in which the first cutting profile and the second cutting profile are formed at substantially 45 degrees to the trailing side.

6. A saw blade substantially as described herein and as shown in Figures 1, 2 and 3.

7. A jigsaw provided with a saw blade comprising a leading cutting side and a trailing side, in which the trailing side comprises a first rear corner and a second rear corner, in which a first cutting profile is formed on the first rear corner, and a second cutting profile is formed on the second rear corner.

8. A jigsaw as claimed in Claim 7 in which a bearing surface is formed between said first cutting profile and said second cutting profile, and in which the jigsaw is provided with guide means which acts against said bearing surface.

9. A jigsaw as claimed in Claim 8 in which the first cutting profile and the second cutting profile comprise cutting teeth which do not extend beyond the plane of the trailing side, and which do not extend beyond the plane of a right and left side respectively of the saw blade, and in which the guide means comprises a roller comprising a rotating drum provided with a circumferential trough in which the saw blade is situated.

10. A jigsaw substantially as described herein and as shown in Figure 4.