TOOL

Description

Background

At building sites and in construction industry is used large quantities of foamed plastics for insulating purpose. Much of this must be adjusted to form and size at the assembly site. Today this is carried out in that the material is sawed with a hand saw (fog saw), an electric piercing saw or a band saw. Much sawdust is produced. On one hand this will produce a wide-spread litter (particularly indoors) as it is electrostatic, and on the other hand it will create problems in the building process, e.g. by raising up to the surface through the concrete and then, among other things, render finishing of the concrete difficult. A fog saw will easily get stuck in the saw cut, a piercing machine saw requires electric power, and when using a band saw, it will be quite a lot of running between the building site and the saw for measurement. It is important that the cuts become straight and exact for avoiding thermal bridges in the constructional insulation and in order to avoid wastage. Foamed plastic is also cut with a metal wire, which is heated in that electric current is passed there through and melts/burns the plastic foam. Poisonous fumes can be formed at this method. The high-speed band saw is principally a machine driven high-speed band saw without teeth. It functions with a large consumption of power, due to the extremely high motional speed of the blade relative the surface of the material to be treated (e.g. a piece of metal), through which it melts its way. To use long sharp knives, or knives with breakable blades does not function in practice as they seize to much.

During cutting, the material is parted off by the sharp, thin knife edge and if the material can be pressed apart by the rest of the knife blade, the tool can force its way along the track. When sawing, milling or grinding, the teeth/the abrasive grains will cut material and form a track in which the tool can advance. A tool can also part and advance through a material, by letting the operating front portion melt, burn or vaporize by means of electric heating.

A simple, flexible tool, which gives perfect cuts, i.a. in foamed building insulation, which will not litter, which requires a minimum of power consumption and force, and which can easily be carried along without need of electric power, thus is missing.

Description of drawing figures

The drawing figures merely show embodiments of the tool, and this can have other forms, structure or another number of elements. Fig. 1 shows the cutting part of the tool (1) and the frontal portion (2) thereof, which performs the actual treatment of the material. Both sides of the blade have the reference number (3) and the width of the edge of the frontal portion (4). The supporting part of the tool has the reference number (5). Fig. 2 shows cross sectional embodiments of the operating part with the frontal portion at the right hand side, where material adjacent the frontal portion is designated (6).

In embodiment (7) the entire blade material has a low heat conducting ability, whereas the frontal portion in embodiment (8) is of another material having low heat conductivity, in (9) the frontal portion is separated from the rest of the cutting part by means of holes (which is also shown in a planar view), in (10) by means of a material reduction, and in (11) in that material adjacent the frontal portion is made of another thermally insulating material.

Fig. 3 shows an embodiment in which the device cuts the material. The material is designated (12) and the direction of the saw cut and the pressure from the tool against the material is randomly shown with the arrow (13). Fig. 4 shows cross sectional details of raised portions at the sides, where example (14) is corrugated.

Fig. 5 shows examples of embodiments such as plate shape (15), thin piercing form (16), interconnected endless belt (17), complete (18) and portion (19) of disc and cylinder (20).

A purpose is a device for parting i.a. constructional plastic foam, such as FRIGOLIT (Styrofoam) and the like. It can also be used for other materials that can be melted/ burned/vaporized, for heat transformable materials, or for materials the strength of which is reduced at temperature increase, or where it is desired to increase the temperature in the cut. Further examples of use is e.g. for deep-frozen products and within surgery. The device can be designed as a separate hand tool, but also as a manually operated machine or a machine, possibly integral with and modified for a cutting table.

This technique means to cut a material by means of frictional heat. The heat can be generated by friction, in that the cutting frontal portion moves towards the material. Then it is required that the motional speed, the pressure and the friction relative to the material are high enough and that the melting temperature or the transforming temperature of the material, and the removal of the heat generation of the cutting surface are low enough to allow the material to be influenced and be cut.

By means of the motion the material is melted/ burned/vaporized, or by means of other heat transformation, the cutting frontal portion is advanced by means of frictional heat through the material, and initiates alternatively splitting. If the edge has a sharp/cutting, filing or sawing design the area of use can be widened. The cut thereupon cools down and remains as a split. By being designed as a blade, it is possible to make the device with a thin frontal portion, which is yet strong. The device shall have the property that the friction heat generated in the frontal portion shall not directly be drained off, but is utilized for the cutting. If for instance it is tried to use the smooth rear side of a fog saw, nothing will happen, as the friction heat generated is drained off in the large steel blade which acts as a cooling flange. The device and its cutting motion may be of several types, such as for instance plate form, an endless joined belt, an entire or a part of a disc, a cylinder (corresponding e.g. to a fog saw, hacksaw, piercing saw, belt saw, circular saw/disc, surgery saw and hole saw) with possible motion combinations of reciprocating, unidirectional, or rotating, arch-formed and linear motions.

Fig. 1 shows a device having a supporting part (5), a plate, the cutting part (1), which not in itself carries out the cutting but the edge of which, the frontal portion (2), cuts the material, which shall be cut by means of friction. The friction of the cutting edge, the frontal portion (2), can be increased by giving it a rough surface or an uneven shape. The frontal portion (2) may also have a wave-shaped contour, like the edge of a bread- knife. For weak, elastic or grainy materials, it should also be sharp in order to make a better cutting work.

Saw teeth giving chips should however be avoided.

The frictional heat generated shall not easily be carried away from the cutting edge, the frontal portion (2). This can be accomplished in that the entire blade material e.g. has a low heat conductivity (7), or by the frontal portion being made of a separate material,

which has a low heat conductivity (8). It can also be arranged in that the frontal portion is separated from the other part of the cutting part by means of recesses (of optional shape, size or number, when the remaining material and the fitting give sufficient strength) (9), by means of thinner material (10) or by insulating material adjacent to the frontal portion.

The portions having low heat conductivity may be homogeneous or alternatively consist of parts having low heat conductivity, formed as short/long particles arranged randomly or in specific patterns, embedded in other material. The structure may also be inverted thus that it is the material in the portion surrounding the particles, which has low heat conductivity. The embodiment (9) and (10) counteracts heat conduction from the edge of the frontal portion by means of reduced overall surface of cut along and adjacent the same. The frontal portion in (11) may be one or more separate details fitted to the cutting part (1), the part (6) adjacent the frontal portion may have hole recesses at the edge. Recesses according to (9) may also be thin slots, for instance cut by laser. The methods may also be combined with each other. The sides (3) of the blade shall have low friction against the surface of the cut in order not to get jammed. Low friction can be achieved by choice of material and/or coating, or by shape, such as e.g. corrugated, or alternatively a structured relief surface, which counteracts the sides (3) of the blade from "sucking" to the smooth sides of the cut. The frontal portion (2) should be thin (4) thus that it can penetrate the material with only a low requirement of melting and a low resistance in the direction of the cut (13). The cut can also be widened by making the frontal portion (2) wave formed sideways, like the setting of a hacksaw. The rest of the cutting part (1) should not be appreciably thicker as it then will get stuck in the cut, even if there is a certain margin as the material (12) possibly can flex away to a certain degree. This makes it possible with e.g. a certain corrugation. At the same time the cutting part (1) needs to be strong and/or stiff in order not to bend or break under influence of the motional forces.

Corrugation or alternatively added reinforcements can be used for giving the combined effect of rigidity and a surface which counteracts sucking. Corrugation of the cutting part (1) can extend up to the frontal portion (2) and be combined with a wave-shaped setting as stated above. The shape of the blade gives a guiding effect in the cut and makes the blade have a self-supporting stiffness. Alternatively the blade can be stretched by a supporting part, such as in a hacksaw in order to obtain a straight cut, or be arranged to maintain the shape by being bent like a hole saw.

The descriptions herein are only intended as examples. The design in sheet metal with a series of holes can be preferred due to its sturdiness, but the tool is not limited to this design and application. At a size of a fog saw the blade may have a thickness of 0.5 mm and can also be given a smooth corrugation, which can be accommodated within the width of a cut of for instance some millimeters (i.e. wave peak height). For the fog saw type the corrugation is preferably made substantially in parallel with the frontal portion, i.e. thus that the peaks and the bottoms extend along this and along the direction of the manual pushing force. The functions can be achieved with, e.g. a carbon fiber reinforced plastic disc with a coarse edge (corresponding to example 7 in Fig. 2), on which for the sake of convenience has been mounted a fog saw handle. A further embodiment is with a piece of sheet steel, readily of spring band-steel, where the sharpened, raw edge of the frontal portion has been separated from the other part of the blade by a repeated series of holes, with an internal distance of about 1 mm, a hole diameter of 5 mm, and with a couple of millimeters of material left at the frontal portion (corresponding to example 9, Fig. 2). Still another embodiment can be a sheet of steel, one side of which has been made into an edge in that it has been coated with e.g. a heat insulating plastic surface, such as powder varnish in a narrow band along the processing edge (corresponding to example 8 in Fig. 2).