GB2154925A

GB2154925A - Cutting fibrous material

Info

Publication number: GB2154925A
Application number: GB08505177A
Authority: GB
Inventors: Borge Leif Nielsen
Original assignee: Rockwool Business Development AS
Current assignee: Rockwool Business Development AS
Priority date: 1984-02-29
Filing date: 1985-02-28
Publication date: 1985-09-18
Also published as: DK129084A; DK129084D0; DE8505529U1; GB8505177D0

Abstract

A method of cutting hard fibrous material particularly slabs thereof containing a large amount of bonding agent using a rotatable knife 10 the, or each blade (11, Fig. 2) of which extends radially beyond a root diameter (2r) of the knife by a distance greater than the depth of the cut. In order to reduce the tendency of the knife to deviate from the intended line of the cut, particularly when slanting cuts are made, the knife is oblong, the difference between the smaller dimension (r, Fig. 2) and the larger dimension (R, Fig. 2) being greater than the depth of the cut in the slab. <IMAGE>

Description

SPECIFICATION Cutting fibrous material The present invention relates to the cutting of fibrous material and more particularly to a method of at least partly cutting through slabs of such material, particularly hard mineral wool with a large content of bonding agent.

For cutting or making grooves into mineral wool rotating sawblades which may be provided with hard metal teeth are normally used. In order to reduce the amount of dust generated it is preferred that the blade be as thin as possible, but as the stiffness of the blade decreases, the risk that the blade will not follow the intended track in the material increases. This leads to inaccurate results and a poor surface finish. In addition, overheating occurs due to the high friction acting between the material and the blade.

One object of the invention is to at least mitigate the above disadvantages.

According to this invention we propose a method of cutting fibrous material particularly hard mineral wool containing a bonding agent, using a rotating knife the, or each blade of which extends radially beyond a root diameter of the knife by a distance greater than the depth of the cut. For cutting a Vgroove, two rotating knives are set at a desired angle relative to one another such that the cuts made intersect to define the bottom of the V-groove.

We also propose a rotating knife for at least partly cutting through slabs of fibrous material, particularly hard mineral wool with a large content of bonding agent, characterised in that the blade of the knife is oblong or alternatively triangular, the shortest distance from the centre to its edge being smaller than the distance from the axis of rotation to the surface of the slab to be cut.

The knife according to the invention does not cut in the same way as a normal sawblade, by which the teeth machine the material at the bottom of the cut, but acts like an axe, cutting its way through the material.

As the blade does not touch the material when the edge hits the end of the cut, the knife will not show any tendency to deviate from the planned line, but cuts exactly in the direction, in which it is moved. The blade of the knife may therefore be thin and does not therefore produce a great deal of dust. As the blade is not in contact with the material all the time, the amount of heat produced is reduced as is the energy required for cutting.

The ability of the knife to follow the intended trace is particularly useful when angled cuts are made, i.e. for making a chamfered cutting on a fibre plate or a carpet etc., and for partly cutting through slabs, for example, when making a V-cut into the plate material.

In a preferred embodiment, the edges of the knife are substantially straight. This ensures that the outer end of the edge will hit the material first, which improves the ability to cut along a predetermined trace.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows apparatus for cutting a Vgroove in a mineral wool slab, and Figure 2 shows a knife-blade for use in the cutting apparatus of Fig. 1.

The apparatus according to Fig. 1 for making V-cuts into a mineral wool slab 1 comprises a housing 2, to which an electric motor 3 is connected. In the housing 2 two shafts 4 and 5 are mounted, the shafts being interconnected by means of bevel gears 6. The output shaft of the electric motor is also provided with a pinion 7 driving a gear 8 on the shaft 4. Each of the shafts 4, 5 has a hub 9 on which a knife blade 10 is mounted. The diameter of the knives 10 is such that in the mineral wool slab, the two cuts will meet to form the bottom of the V-groove.

Fig. 2 shows a knife 10 for use in the apparatus of Fig. 1. The knife 10 has a larger radius R, the size of which corresponds to the depth of the desired cut, and a smaller radius, which is so small that the knife is free from the material at this radius. From the root diameter (i.e. the smaller radius) the knife has wing like blades 11 extending to the larger radius, the wings or blades 11 preferably having straight edges 1 2. The knife shown in Fig. 2 has two wings, but an embodiment having three wings may also be used. The knife 10 has a central mounting hole 1 3 and two further holes 14, into which a pair of driving studs is fitting. The knife is fastened in a conventional manner with a nut.Due to the fact that the smaller distance r of the knife is smaller than the distance between the hub 9 and the slab 1 in the cutting plane, the knife 10 will hit the slab first at the larger diameter R, and therefore, each new cut starts correctly in the plane of the knife. Therefore, the knife will even in a slanted cut provide a clean and accurate cut and does not tend to deviate from the intended line.

1. A method of cutting fibrous material particularly hard mineral wool containing a bonding agent, using a rotating knife the, or each blade of which extends radially beyond a root diameter of the knife by a distance greater than the depth of the cut.

2. A method according to claim 1 for cutting a V-groove in fibrous material wherein two rotating knives are set at a desired angle relative to one another such that the cuts made intersect to define the bottom of the Vgroove.

3. A rotating knife for at least partly cut

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Cutting fibrous material The present invention relates to the cutting of fibrous material and more particularly to a method of at least partly cutting through slabs of such material, particularly hard mineral wool with a large content of bonding agent. For cutting or making grooves into mineral wool rotating sawblades which may be provided with hard metal teeth are normally used. In order to reduce the amount of dust generated it is preferred that the blade be as thin as possible, but as the stiffness of the blade decreases, the risk that the blade will not follow the intended track in the material increases. This leads to inaccurate results and a poor surface finish. In addition, overheating occurs due to the high friction acting between the material and the blade. One object of the invention is to at least mitigate the above disadvantages. According to this invention we propose a method of cutting fibrous material particularly hard mineral wool containing a bonding agent, using a rotating knife the, or each blade of which extends radially beyond a root diameter of the knife by a distance greater than the depth of the cut. For cutting a Vgroove, two rotating knives are set at a desired angle relative to one another such that the cuts made intersect to define the bottom of the V-groove. We also propose a rotating knife for at least partly cutting through slabs of fibrous material, particularly hard mineral wool with a large content of bonding agent, characterised in that the blade of the knife is oblong or alternatively triangular, the shortest distance from the centre to its edge being smaller than the distance from the axis of rotation to the surface of the slab to be cut. The knife according to the invention does not cut in the same way as a normal sawblade, by which the teeth machine the material at the bottom of the cut, but acts like an axe, cutting its way through the material. As the blade does not touch the material when the edge hits the end of the cut, the knife will not show any tendency to deviate from the planned line, but cuts exactly in the direction, in which it is moved. The blade of the knife may therefore be thin and does not therefore produce a great deal of dust. As the blade is not in contact with the material all the time, the amount of heat produced is reduced as is the energy required for cutting. The ability of the knife to follow the intended trace is particularly useful when angled cuts are made, i.e. for making a chamfered cutting on a fibre plate or a carpet etc., and for partly cutting through slabs, for example, when making a V-cut into the plate material. In a preferred embodiment, the edges of the knife are substantially straight. This ensures that the outer end of the edge will hit the material first, which improves the ability to cut along a predetermined trace. One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows apparatus for cutting a Vgroove in a mineral wool slab, and Figure 2 shows a knife-blade for use in the cutting apparatus of Fig. 1. The apparatus according to Fig. 1 for making V-cuts into a mineral wool slab 1 comprises a housing 2, to which an electric motor 3 is connected. In the housing 2 two shafts 4 and 5 are mounted, the shafts being interconnected by means of bevel gears 6. The output shaft of the electric motor is also provided with a pinion 7 driving a gear 8 on the shaft 4. Each of the shafts 4, 5 has a hub 9 on which a knife blade 10 is mounted. The diameter of the knives 10 is such that in the mineral wool slab, the two cuts will meet to form the bottom of the V-groove. Fig. 2 shows a knife 10 for use in the apparatus of Fig. 1. The knife 10 has a larger radius R, the size of which corresponds to the depth of the desired cut, and a smaller radius, which is so small that the knife is free from the material at this radius. From the root diameter (i.e. the smaller radius) the knife has wing like blades 11 extending to the larger radius, the wings or blades 11 preferably having straight edges 1 2. The knife shown in Fig. 2 has two wings, but an embodiment having three wings may also be used. The knife 10 has a central mounting hole 1 3 and two further holes 14, into which a pair of driving studs is fitting. The knife is fastened in a conventional manner with a nut.Due to the fact that the smaller distance r of the knife is smaller than the distance between the hub 9 and the slab 1 in the cutting plane, the knife 10 will hit the slab first at the larger diameter R, and therefore, each new cut starts correctly in the plane of the knife. Therefore, the knife will even in a slanted cut provide a clean and accurate cut and does not tend to deviate from the intended line. CLAIMS

3. A rotating knife for at least partly cut ting through slabs of fibrous material, particularly hard mineral wool with a large content of bonding agent, characterised in that the blade of the knife is oblong or alternatively triangular, the shortest distance from the centre to its edge being smaller than the distance from the axis of rotation to the surface of the slab to be cut.

4. A knife according to claim 3, characterised in that the knife is oblong or alternatively triangular, the difference between its smaller radius (r) and its larger radius (R) being greater than the intended depth of cutting.

5. A knife according to claim 3 or claim 4, characterised in that the edges of the knife are substantially straight.