Abstract:
There is provided a tool blade, comprising a backing strip particles of abrasive material and a binder layer of binding material which binds the abrasive particles along an edge of the backing strip, wherein the edge of the backing strip is pre-formed with teeth, on which the abrasive particles are bound by the binding material. A profiled cutting portion extends beyond the pre-formed teeth. The pre-formed teeth are shaped as generally triangular waves or are flattened at least partially along an upper edge on which the cutting portion is at least partially disposed. A method of making such a blade is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. §119 of Great Britain Patent Application Nos. 1512361.5, filed Jul. 15, 2015, and 1519222.2, filed Oct. 30, 2015, the disclosures of which are hereby incorporated herein by reference in their entireties. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to tool blades and to methods of making tool blades. 
       SUMMARY OF THE INVENTION 
       [0003]    Examples of the present invention provide a method of making a tool blade, in which:
   a. a backing strip is provided;   b. particles of abrasive material are provided;   c. binding material is provided;   d. and the binding material forms a binder layer which binds the abrasive particles along an edge of the backing strip;   
 
         [0008]    wherein the edge of the backing strip is preformed with teeth, prior to the introduction of abrasive particles and binding material; 
         [0009]    and wherein the binding material is heated by a beam of radiation to form the binder layer. 
         [0010]    The teeth may be preformed to be undersize relative to a desired size, the abrasive particles and binding material coating the teeth to increase the tooth size to the desired size. 
         [0011]    Alternatively, the teeth may be preformed to be undersize relative to a desired size, the abrasive particles and binding material coating the teeth to increase the size beyond the desired size, the teeth being processed to return the tooth to the desired size. The teeth may be processed by grinding or other machining, or by laser cutting. The processing may create one or more sharp cutting edges. 
         [0012]    The teeth may be formed undersize relative to a desired size, and to a desired shape. The abrasive particles and binding material may form a uniform layer at the surface of the finished teeth. 
         [0013]    The teeth may be ground for sharpness. The teeth may be ground after coating with abrasive particles and binding material. 
         [0014]    The backing strip may be coated only at the cutting portion of the teeth. 
         [0015]    The binding material may be heated by laser radiation. 
         [0016]    The abrasive particles may be introduced by projecting or streaming onto the edge of the backing strip, and a high temperature bonding matrix powder may be projected or streamed separately to create precise positioning of the particles. The abrasive particles may have a particle size of 500 microns or less. The abrasive particles may comprise tungsten carbide, or only tungsten carbide, or may comprise other hard metals. The abrasive particles may comprise at least one super abrasive material (such as diamond or cubic boron nitride). 
         [0017]    The binding material may be introduced in particle form. The binding material may be introduced by separately projecting, streaming or cascading onto the edge of the backing strip. The binding material may comprise a braze material. 
         [0018]    Examples of the present invention also provide a computer-readable medium having computer-executable instructions adapted to cause a 3D printer to print a tool blade in accordance with the method set out above. 
         [0019]    Examples of the present invention provide a tool blade, comprising:
   a. a backing strip;   b. particles of abrasive material;   c. and a binder layer of binding material which binds the abrasive particles along an edge of the backing strip;   
 
         [0023]    wherein the edge of the backing strip is preformed with teeth, on which the abrasive particles are bound by the binding material. 
         [0024]    The binding material and abrasive particles may form a cutting portion profiled to providing a cutting edge. 
         [0025]    The profiled cutting portion may extend beyond the pre-formed teeth. 
         [0026]    The pre-formed teeth are preferably shaped as generally triangular waves. 
         [0027]    The pre-formed teeth may be flattened at least partially along an upper edge on which the cutting portion is at least partially disposed. 
         [0028]    The teeth of the backing strip may be undersize relative to a desired size, the abrasive particles and binding material coating the teeth to increase the tooth size to the desired size. 
         [0029]    Alternatively, the teeth may be preformed to be undersize relative to a desired size, the abrasive particles and binding material coating the teeth to increase the size beyond the desired size, the teeth being processed to return the tooth to the desired size. The teeth may be processed by grinding or other machining, or by laser cutting. The processing may create one or more sharp cutting edges. 
         [0030]    The teeth may be formed undersize relative to a desired size and to a desired shape. The abrasive particles and binding material may form a uniform layer at the surface of the finished teeth. 
         [0031]    The teeth may be ground for sharpness. The teeth may be ground after coating with abrasive particles and binding material. 
         [0032]    The backing strip may be coated only at the cutting portion of the teeth. 
         [0033]    The abrasive particles may have a particle size of 500 microns or less. The abrasive particles may comprise tungsten carbide, or only tungsten carbide, or may comprise other hard metals. The abrasive particles may comprise at least one super abrasive material (such as diamond or cubic boron nitride). 
         [0034]    The binding material may comprise a braze material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]    Examples of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: 
           [0036]      FIG. 1  is a schematic side view indicating a method of making a tool blade; and 
           [0037]      FIGS. 2, 3, 4 and 5  illustrate teeth of the tool blade on an enlarged scale. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]      FIG. 1  illustrates a method of making a tool blade indicated generally at  10  in  FIG. 1 , but with detail removed in the interests of clarity. In this example, a backing strip  12  is provided. Binding material  14  is provided. This is in powder form and in this example, is projected as a beam or jet onto the backing strip  12  from a source indicated as a hopper  18 . In this example, this occurs at a workstation  21  as the backing strip  12  is moving past the workstation  21  in the direction of the arrow  23 . One workstation is shown, having two hoppers  18 ,  20 . Other numbers of workstations and hoppers could be chosen. 
         [0039]    The binding material powder  14  and the backing strip  12  are heated in the workstation  21  by a beam of radiation  22  from a radiation source  24  to form a binder layer (to be described). Abrasive particles  26  are also provided. The particles  26  are provided at the workstation  21  from a hopper  20  in this example. The abrasive particles are to be bound along an edge  11  of the backing strip  12 . This is achieved by the binder layer which is being formed by the binding material. 
         [0040]    The edge  11  of the backing strip  12  is preformed with teeth  16 , prior to the introduction of abrasive particles  26  and binding material  14 . In this example, the teeth  16  are shaped as generally triangular waves along the edge  11 . Other shapes could be chosen, including shapes which have straight or curved portions, re-entrant portions, additional crests or other features. 
         [0041]    The abrasive particles  26  may comprise tungsten carbide. In one example, the abrasive particles  26  comprise only tungsten carbide. Other abrasive particles could be used such as hard metals or super abrasives (such as diamond or cubic boron nitride). The abrasive particles may have a particle size of 500 microns or less. 
       Apparatus Used in the Method 
       [0042]    In more detail,  FIG. 1  illustrates a backing strip  12  in the form of a long steel strip. After the strip  12  has been treated to create a cutting edge along the edge of the strip  12 , the strip will be suitable for use as a tool in the form of a linear edge blade for band saws, hacksaws, jigsaws, reciprocating saws, hole saws and other similar tools. Other materials could be used for the backing strip  12 . 
         [0043]    In this example, the edge  11  of the strip  12  is moved relative to the workstation  21 , for the formation of the blade  10 . The workstation  21  includes hoppers  18 ,  20  for providing material in the form of powder projected onto the edge  11  of the strip  12 . In this example, two separate hoppers  18 ,  20  are illustrated and will be described as supplying binding material  14  and abrasive material  26 , respectively, so that these materials can be supplied separately or together to the edge  11  of the strip  12 . In other examples, there may be only a single source of these materials, in a mixture. Mixtures of more than one binding material may be used, provided by respective sources or from one or more combined sources. The control arrangements of the hoppers  18 ,  20  allow the delivery of binding material  14  and abrasive particles  26  to be controlled. The rate of delivery may be controlled, and the delivery may be controlled to start and stop. It is envisaged that delivering the materials separately, to be mixed at the edge  11 , will improve the level of control available, especially if the different materials have different particle sizes or weights. 
         [0044]    The abrasive particles  26  may comprise tungsten carbide, or comprise only tungsten carbide. 
         [0045]    The workstation  21  also includes a radiation source  24 . In this example, the radiation source  24  is a laser light source. Other types of radiation source could alternatively be used, such as electron beams, plasma beams and others. The purpose of the radiation source  24  is to create heating in the binding material  14 , at the edge  11  of the strip  12 , in order to form a binder layer, as will be described. Accordingly, a choice of radiation source  24  can be made by considering the nature of the binding material  16 , the material of the backing strip  12  and the material of the abrasive particles  26 , in order to achieve the results which will be described. 
         [0046]    The workstation  21  may be fixed in position, with a feed mechanism (not shown) being provided to feed the strip  12  past the workstation  21 . This may be done in a continuous or stepwise fashion. Alternatively, or in addition, the workstation  21  (and in particular, the laser  24 ) may be arranged to scan along the edge  11  of the strip  12  or toward and away from the edge of the strip  12 , either by mechanical means or by optical means. The laser  24  may also be arranged to provide variable intensity, pulses of variable duration, or streams of pulses which have a variable duty cycle (the ratio between the length of on periods and the length of off periods). The frequency or wavelength of the radiation may be varied. The focus position or the shape or size of the focus of the radiation beam may be varied. The incident angle or drag angle of the radiation relative to the strip  12  may be varied. The scanning speed of the radiation, relative to the strip  12 , may be varied. These or other variations may be used to create controllable heating effects in the strip  12 . This allows the temperature to be controlled at the surface of the binder layer being formed. 
         [0047]    A second workstation is illustrated at  32  and is a finishing station for performing a grinding or other machining operation, laser cutting, or otherwise for finishing the blade, as will be described. Alternatively, the second workstation  32  may be part of a separate line for finishing the blade. In a further alternative, the workstation  32  may provide initial machining or finishing, to create a blade in a raw state for subsequent final finishing elsewhere. 
         [0048]    The workstations  21 ,  32  may be controlled by one or more computing devices  25 . Consequently, there may be computer-executable instructions adapted to cause the workstations  21 ,  32  to perform as a 3D printer system to print an abrasive tool blade in accordance with the method being described herein, the instructions being in a computer-readable medium either within the device  25 , or removable from the device  25 , as illustrated at  25 a. 
       Form of the Backing Strip 
       [0049]    The backing strip  12  is preformed with teeth  16 . Various different shapes and sizes of teeth  16  could be used. The teeth  16  could all be of the same size and shape. Alternatively, tooth size and/or tooth shape could vary along the backing strip  12 . 
         [0050]      FIG. 2  illustrates a tooth  16  which is generally triangular wave crest in shape and has an exposed tip  28  which will form the cutting portion of the tooth  16 , when in use. A coating  30  is formed on the tooth  16  ( FIG. 3 ) by the binding material  14  and the abrasive particles  26 . In  FIG. 3 , it can be seen that the outer surface of the coating  30  has a different shape to the tooth  16  of the backing strip  12 , and is larger in size. 
       Formation of a Binder Layer and Coating 
       [0051]      FIG. 1  illustrates the situation as the binder layer  32  is being formed to provide the coating  30 . This is the process at the workstation  21 . Binding material  14  is projected onto the edge  11  of the strip  12  and the laser  24  is used to illuminate the edge  11  of the strip  12  and the binding material. This has the effect of creating heating. The heating effect causes the binding material to bind to the backing strip  12 . In one example, the binding material and/or the backing strip  12  become molten, to achieve a welding effect between the materials. Abrasive particles  26  are also projected onto the edge  11  of the strip  12 , so that they become bound along the edge  11  by the action of the binding material  14 . The workstation  21  may be controlled so that the backing strip  12  is coated only at the tip  28  of the teeth  16 . Alternatively, the backing strip  12  may be coated continuously along its edge. 
         [0052]    The binding material may consist of or include a ductile braze material. Alternatively, a hard braze material may be used. The hard braze material may be a nickel braze material. A desired function of the binding material is to create a hard tooth tip or blade edge or other cutting portion of the teeth  16 , this tip, edge or portion being also abrasive by virtue of the presence of the abrasive particles  26  and the quality of their bond to the backing strip  12  achieved by the binding material  14 . 
       Tooth Shape and Tooth Finishing 
       [0053]    In  FIG. 2 , the preformed tooth  16  has a rounded wave shape which is generally triangular in shape. The tooth  16  is coated at the workstation  21  with the abrasive particles  26  and binding material  14 . The coated tooth  16  is illustrated in  FIG. 3 . In this example, this coating process increases the tooth size to a desired size indicated by the external outline of the coating  30  ( FIG. 3 ). Prior to coating ( FIG. 2 ), the tooth  16  is under size as compared with the desired size. In this example, the tooth shape also changes while the tooth  16  is coated. That is, the initial tooth shape is not the same as the desired tooth shape. In particular, a sharp edge  29  is formed by the coating process. 
         [0054]    After coating the tooth  16 , the tooth  16  may be finished by a grinding operation at the second workstation  32  ( FIG. 1 ). For example, the tooth  16  may be ground for sharpness, particularly along the edge  29  of the tip  28 . 
         [0055]      FIG. 4  illustrates an alternative possibility. The uncoated tooth  16  is again a rounded wave shape which is generally triangular in shape and is again coated in the workstation  21  by a coating  30  of abrasive particles  26  and binding material  14 . In this example, the tooth  16  is initially undersize as compared with the desired size. The desired size is assumed in this example to be the size shown in  FIG. 3 , for ease of comparison with the first alternative. The coating  30  is applied sufficiently thickly to increase the tooth size beyond the desired tooth size. This is illustrated in  FIG. 4 , in which the desired tooth size (corresponding with  FIG. 3 ) is indicated by a broken line  34 , and different shading is used inside and outside the desired tooth size, solely for illustrative purposes. 
         [0056]    After the tooth  16  has been coated to the oversize condition of  FIG. 4 , the tooth  16  passes to the second workstation  32 . The workstation  32  returns the oversize tooth  16  back to the desired tooth size. This may be by grinding or other machining, laser cutting, or another form of processing. 
         [0057]    In these two examples, the initial tooth size is undersize and the initial tooth shape is not correct as compared with the desired tooth size and shape. In consequence, the coating  30  is not uniform in thickness across the surface of the finished tooth. In other examples, the coating process may leave the shape of the tooth unchanged from an initial shape of the tooth  16 , in which case the coating  30  will be uniform in thickness across the surface of the finished tooth. 
         [0058]      FIG. 5  illustrates two teeth finished as described above ( FIGS. 3 and 4 ), and an uncoated tooth in the form which would be observed prior to the tooth reaching the workstations  21 . 
         [0059]    The examples described above are expected to provide an improved cutting blade for various reasons, including the following. The mechanical integrity of the teeth is primarily provided by the preformed shape of the teeth on the backing strip, and many different shapes can readily be created along the strip by conventional manufacturing techniques such as machining, stamping, laser cutting, grinding etc. The coating provided by the workstation  21 , together with any finishing (if any) provided by the workstation  32 , is expected to create a superior tooth performance, for example by virtue of the precise shaping and the ease of varying the tooth shape to suit various materials or applications. Speed of production is expected to increase, with the resulting lower cost, particularly because of the presence of the tungsten carbide or other abrasive material, but without prejudicing the mechanical integrity provided by the preformed teeth. The precise control available from the laser will also minimise the heat affected zone, retaining more of the flexibility and ductility of the backing strip. 
         [0060]    It is envisaged that the blade may be coated as described and then sold in uncut strip form for finishing by others, including any required grinding or finishing steps. 
         [0061]    Many variations and modifications can be made to the techniques and apparatus described above, without departing from the scope of the present invention set forth herein. For example, many different materials, or combinations of materials, shapes, sizes, relative shapes and relative sizes of structures can be chosen. 
         [0062]    While endeavoring in the foregoing specification to draw attention to those features of the present invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.