The present invention relates to a method for producing •. tool strip for the manufacture of tools which are pri¬ marily intended for material removing or cutting work, and for the manufacture of said tools, such as saw blades, knife blades and the like, where said strip and said tools include a metallic material which has been adapted to a high degree of hardness and wear resistance.

The invention also relates to apparatus for carrying out the method, and strip and tools.

The metallic material adapted to a high degree of hardness and wear is intended to form the cutting parts of the tool, i.e. the saw teeth, knife edge or corresponding cutters.

Tools of this kind are mainly produced from strip material, which is of the same kind as the material adapted to a high degree of hardness. This material is most often highly expensive, relatively speaking, due to its high content of alloying substances and to the high yield losses experienced in manufacture as a result of the high content of alloying substances. One serious drawback with this method, in which the whole tool, or substantially the whole tool is made of material which has been adapted to a high degree of hardness is that the tool is encumbered with the low toughness of the material .

Blades of this kind are also produced primarily from strip material, partly of a simple and less expensive kind,

intended primarily for carrying parts and attachement parts, and partly of a more expensive kind intended for cutting parts, wherewith strip parts of both kinds are joined together, by means of welding, mould casting or the like, such as to form a tool. Although the material costs are lower when applying this method of manufacture, the method is less attractive because of the number of additional manufacturing operations involved, primarily the welding or like operations, and also because it is difficult to obtain a holdable join, inter alia because only a very limited join surface is available.

Also known is a method in which a rectangular duplex blank-section is produced by casting complementary mate- rial on a part section. The method is low productive and necessitates the use of complicated and expensive mould casting procedures.

The present invention relates to a highly productive method which enables tools of the kind meant here to be produced at low costs and with which the resultant tools will not be encumbered with the- drawbacks of given known tools, such as weak zones at the join, toughness deficien¬ cies, and high costs.

The invention thus relates to a method for producing tool strip for the manufacture of tools which are mainly in¬ tended for material removal, cutting or like work, and to the manufacture of such tools, where said strip and tools include parts made of a metallic material, such as steel, which has been brought to a high degree of hardness and wear resistance and therewith suitable for forming the material removing or cutting parts of the tool, and in which manufacture a strip-like element, said strip, is effected by shaping an elongated blank which comprises

more than one metallic material, where one or more of said metallic materials, e.g. the material which has been adapted to a high degree of hardness etc., is applied by a casting or moulding technique. The method is particu- larly characterized in that casting of said one or more metallic materials is effected in an essentially known manner by direct casting of molten metal which is caused to run from a melt outlet part of a container and caused to form a continuous wire-like or rod-like body through stabilization with the aid of a wire-like body which passes continuously through the outlet part, whereafter the contin¬ uous jet of molten metal surrounding the wire-like body is caused to solidify around said body and collected, or by so-called dip forming in which a wire-like body is passed through a molten metal bath and a layer of the bath metal is frozen onto the wire-like body, wherein the wire-like body forms a central part of said blank and wherein one or more such metallic materials -are applied such as to form a substantially concentric part of the blank when seen in cross-section.

The invention also relates to apparatus for forming strip for the manufacture of tools which are primarily intended for material removing or cutting work, and for the manu- facture of such tools, said strip and tools including parts made from a metallic material, such as steel, which has been adapted to a high degree of hardness and wear resistance and therewith suited and intended to form mate¬ rial removing or cutting parts. The apparatus is particu- larly characterized by the provision of devices for pro¬ ducing a strip-like body, said strip, by shaping an elon¬ gated blank while only slightly reducing the cross-sec¬ tional dimensions of the blank, or substantially in the absence of any such reduction, said blank comprising one or more metallic materials, and in which blank one or more

of said metallic materials, e.g. said material which has been adapted to a high degree of hardness, is present in the form of an essentially concentric part, with regard to the cross-section of the blank, which has been applied by a casting or molding technique.

The invention also relates to tools which are primarily intended for material removing or cutting work and which have the form of a substantially strip-like element, or strip, and include parts made of a metallic material, such as steel, which has been adapted to a high degree of hard¬ ness and wear resistance and is therewith suitable, and intended, to form material removing or cutting parts of the tool, and also to strip where said strip-like element, said strip, is produced by shaping an elongated blank and where one or more of said metallic materials, such as ma¬ terial of the kind which has been adapted or brought to a high degree of hardness etc. , are applied by -a casting or molding technique. The tools and strip are mainly charac- terized in that said casting is effected by the direct casting of a molten metal which is brought to run from a metal bath container through a melt outlet part therein and caused to form a continuous wire-like body by stabil¬ izing with a wire-like body which passes continuously through the outlet part, whereafter the continuous jet of molten material surrounding the wire-like body is caused to solidify around the wire and collected, or is effected by so-called dip-forming in which a wire-like body is passed through a molten metal bath and a layer of metal is frozen onto said body, and in which one or more metallic layers are applied to said body such as to form a sub¬ stantially concentric part with regard to the cross-sec¬ tion of the blank.

The invention will now be described in more detail with

reference to a number of exemplifying embodiments thereof and with reference to the accompanying drawings, in which

Figure 1 is a cross-sectional view of a wire-like blank for use with the inventive method and tool ;

Figure 2 illustrates shaping of a blank, by rolling the blank into a strip-like body in accordance with the in¬ vention;

Figure 3 illustrates an inventive strip-like body in cross-section;

Figure 4 is a cross-sectional view of a first embodiment of a tool according to the invention;

Figure 5 is a cross-sectional view of a second embodiment of a tool according to the invention ^' ;

Figure 6 illustrates, in smaller scale, part of the tool shown in Figure 5 seen in the direction of the main plane of the tool ;

Figure 7 is a cross-sectional view of a third embodiment of a tool according to the invention; and

Figure 8 is a cross-sectional view of a saw blade whose teeth comprise solely hard wear-resistant material.

In Figure 1 the reference numeral 1 identifies an elon¬ gated blank of essentially circular cross-section intended for the manufacture of strip-like bodies, or strip. The strip is thus intended for manufacturing tools which are mainly intended for material removing or cutting work, and the strip and tools include parts of a metallic material,

such as steel, which has been adapted or brought to a high degree of hardness and wear resistance and which is there¬ with suitable, and intended, to form the material removing or cutting parts of the tool.

The blank 1 comprises more than one metallic material, where.one or more of said metallic materials, such as ma¬ terial of said kind which has been adapted to a high degree of hardness etc. , are located as a substantially concentric part 2, as seen in the cross-section of the blank, which has been applied by a casting or moulding technique. The material need not have said high degree of hardness etc. at the blank stage. It is more prefer¬ able to bring the material to said high degree of hardness by, for instance, heat treating the material when shaping etc. has been completed. Thus, the material adapted to a high degree of hardness etc. may possess this degree of hardness or may be brought to said high degree of hard¬ ness, for instance, by heat treatment. The blank, also includes a central part 3 which may have a circular cross- sectional shape, although such shape is not absolutely necessary. The embodiment illustrated in Figure 1 in¬ cludes a part 2 shown in full lines, although further concentrical parts 2 are conceivable, as illustrated in chain lines in the Figure.

In accordance with one preferred embodiment of the inven¬ tion the blank is produced in the form of a duplex with regard to material composition and includes herewith, in cross section a central part 3 and an outer layer which extends concentrically around the central part.

In accordance with the invention, said casting or moulding operation is effected in an essentially known manner, sub- stantially in accordance with Swedish Patent 8003487-9, by

the direct casting of a molten metal, which is allowed to run from a container through a melt outlet port therein and caused herewith to form a continuous, wire-like body by stabilizing with the aid of a wire-like body which passes continuously through the outlet port, whereafter the continuous, exiting molten jet surrounding the wire¬ like body is caused to solidify around the wire and is collected.

Alternatively, the casting or moulding operation can be effected by so-called dip-forming, where a wire-like body is caused to pass through a molten metal bath and a layer of the metal is frozen onto the wire-like body.

Thus, in the aforesaid instances the wire-like body will form a central part 3 of the blank 1 and the solidified metal will form a concentrical part 2.

A strip-like body 4, said strip.4, is intended to be pro- duced, in accordance with the invention, by re-shaping the cross-section of the blank 1, i.e. to flatten the blank 1. This is effected by re-distributing the cross-sectional material while maintaining reduction of the cross-section¬ al size of the blank at a relatively slight level, or at an insignificant or substantially non-existant level. As beforementioned, the body 4 is intended for the manufac¬ ture of tools 5, Figures 4-8, intended for material re¬ moving or cutting or like work, the blank 1 being intended to be deformed into a strip 4 which includes a centrally located strip-like layer 6, which is formed by the de¬ formed central part 3, and at least one layer 7 which em¬ braces the layer 6 and forms at least two strip-like layers 7' , 7", one on each respective side of the layer 6.

Edge parts 8, teeth 8 or like elements which form material

removing or cutting parts 8 of the tool are formed on the body 4 by grinding, clipping or like operations.

In the embodiment of blade 5 illustrated in Figure 4, an edge 8 has been produced by bevelling or chamfering one long side 9 of the body, 4. Figures 5 and 6 illustrate a saw blade, in which one long side 9 has been provided with teeth 8. Conceivably, both long sides 9 can be provided with teeth 8,

The layer 1 , and herewith the layers 7', 7" of at least the embodiments illustrated in Figures 4-6 and 8 comprise said material which has been adapted to a high degree of hardness and wear resistance, for instance high-speed steel, this layer 7 corresponding to one or more cast or molded layers 2 of the blank 1. The central layer 6 and corresponding central part 2 suitably comprise a tough and relatively inexpensive material, such as a low-alloy steel, for example a low-carbon steel of commercial type.

Embodiments are conceivable which instead, or at least the central part 3, comprise said hard material, whereby an embodiment of edge parts 8, e.g. according to Figure 7 is suitable.

As illustrated in Figure 8, the tool 5, which in this case is a saw blade, can be configured so that edge or teeth 8 solely include one material, suitably a hard and wear resistant material. Embodiments according to, e.g., Fig- ure 5 are also conceivable in which the teeth 8 are of duplex construction.

The apparatus for reshaping the blank 1 to an elongated body 4 illustrated schematically in Figure 2 includes at least one pair of rollers 10 between which the blank 1

is intended to be deformed by rolling. The rolls 10 preferably have a planar roll path, i.e. are cylindrical, at the location where deformation of the blank takes place. The roll diameter D is preferably so adapted in relation to the diameter of the blank 1 and reduction of the height of the blank during its passage through the roll nip as to achieve the desired increase in width as the blank is rolled.

According to one embodiment of apparatus according to the invention suitable devices, not shown, are provided for dividing the produced strip-like bodies 4 in the direction of their longitudinal axes into at least ^' two parts, these thus form strip-like _% parts being intended for the manu- facture of blades 5. There is obtained in this regard an edge 11, e.g., in accordance with the part shown in full lines in Figure 4.

As will be understood the choice of material of the parts 2, 3 both individually and with regard to the combination, and therewith of the strip-like body 4, is made with re¬ gard to the use for which the blade is intended. Thus, the ^' material adapted for high wear resistance may comprise, e.g., high-speed steel, stainless steel or a high carbon steel other than high-speed steel. It is also conceivable to produce both the part 3 and the part 2 from essentially the same metallic material, where the part or parts 2 are applied by casting or molding techniques but where the material in said parts 2, 3 can be considered in this con- text to be mutually different metallic materials.

The apparatus and blade function, and also the tool ac¬ cording to the invention and the inventive method will be understood in all essentials from the aforegoing.

A blank 1, whose cross-section preferably comprises solely partially a material adapted to a high degree of hardness etc. intended to form material removing parts 8 of a tool 5 is thus produced partially by means of casting or mould- ing in the aforedescribed manner. The blank 1 is re¬ shaped so as to achieve the desired distribution of mate¬ rial across the cross-section of the strip-like body 4, The blank is shaped to a strip-like body 4, e.g., by roll¬ ing the blank. There are formed in this way strip-like layers which, subsequent to being ground or corresponding¬ ly worked, form material removing or cutting parts of the tool .

The reduction in cross-section and the increase in width achieved when rolling the blank can be controlled by the geometry of the rolls. With an increasing contact zone 12 in the rolling direction between rolls 10 and blank 1 in relation to the width of the .blank, the relative in¬ crease in width will increase and said reduction decrease.

It will be understood from the aforegoing that the inven¬ tion enables a blade 5 of the kind meant here to be pro¬ duced at much lower costs than is possible with known techniques . Direct casting affords a high degree of flexibility with regard to the selection of material etc., and results in high production capacity. Re-shaping of the blank in accordance with the aforegoing also contri¬ butes to this high degree of flexibility. The part 2, when applicable the stabilizing wire, can be produced at low cost, since it comprises a simple material, such as low-carbon steel of commercial steel type. Particularly good adhesion is obtained between the parts 2, 3, since the boundary surface is created at the casting or moulding stage. It is, of course, important that the cross-sec- tional shape cast will lie close to the cross-sectional

shape of the finished product.

The invention has been described in the aforegoing with reference to various embodiments thereof. It will be understood that more embodiments are conceivable and that minor modifications can be carried out without departing from the concept of the invention.

For example, embodiments are conceivable in which the core 2 and the outer layer 3 comprise essentially the same material .

When suitable from the aspect of manufacture, reshaping of the blank can be effected with the blank in a hot state, in which case reshaping of the blank is preferably ef¬ fected in connection with the casting operation and the blank being preferably permitted to cool to only a slight extent subsequent to being cast.

Naturally, the body 4 may be hand moulded for the manu¬ facture of tools in a number of. ways. It is suitable, in many instances, for at least one part of at least one long side of the body 4 to incorporate material removing or cutting parts 8 of a tool produced form the body 4.

As beforementioned, the cross-sectional dimensions of the elongated blank will suitably lie close to the cross- sectional dimensions of the strip-like body. A substan¬ tially round blank having a diameter of about 1-8 mm is considered suitable for many applications. Consequently, the dimensions of the blank subsequent to being cast will suitably lie within this range. It will be understood, however, that blank dimensions which lie outside this range are also conceivable.

The invention shall not therefore be considered limited to the aforedescribed and illustrated embodiments, since modifications and variations can be made within the scope of the following claims.