TOOL

Abstract: The present invention refers to a tool (14) intended to be rotatably mounted in a cutter (10), said tool (14) is in operative position carrying out ice-scraping and/or snow clearing of a road surface (17), and that the longitudinal axis (16) of the tool (14) forms an angle (α) being in the range of 20° - 90°, and that a hard material tip (15;15′;15″) of the tool (14) contacts the road surface in operative position of the tool. The invention also refers to the hard material tip (15;15′;15″) separately. The aim of the invention is to present a tool (14) and especially the design of the hard material tip (15;15′;15″) that is especially adapted for ice-scraping. The invention is characterized in that the hard material tip (15;15′;15″) includes a cylindrical or slightly conical portion (20;20′;20″) and a smoothly curved shape-defining surface (21;21′;21″) connected to said portion (20;20′;20″).

Description: The present invention refers to a tool intended to be rotatably mounted in a cutter, said tool is in operative position carrying out ice-scraping and/or snow clearing of a road surface, and that the longitudinal axis of rotation of the tool forms an angle relative to the road surface in the range of 20° to 90°, and that a hard material tip of the tool contacts the road surface in operative position of the tool, that the hard material tip includes a nearest to the tool located cylindrical or slightly conical portion, and that the free end of the hard material tip includes shape defining surfaces being symmetrical relative to the axis of rotation of the tool. The invention also refers to the hard material tip separately. From EP-A-0 179 034 is previously known a cutter of the type mentioned above. The tools used with this cutter are of standard type, i e the same type of tools that are used for cutting asphalt or breaking coal etc. These tools are thus designed to carry out a cutting action and consequently a common feature is that the hard material insert has a relatively pointed design to minimize the cutting forces. From GB-A-2 146 058 is previously known a cutting tool that is intended to be used to cut a variety of soft materials such as coal. Although the tool according to GB-A-2 146 058 has a smoothly curved tip, said tool is not suitable to be used for ice scraping and/or snow clearing. The tools to be used with a cutter for ice-scraping/snow clearing, however, must have other characteristics than the tools used for cutting action. When a cutter armed with tools of the actual type works the road surface a rolling contact will be established between the tool tips and the road surface. A tool used for cutting action will be subjected to much higher insert-bending forces than a tool used in accordance with the present invention. This difference concerning the forces acting on a tool is reflected in the design of a tool according to the present invention. As an important consequence of the design according to the present invention the volume of wear of the hard material tip increases so as to achieve an extended length of life. The present invention has the aim of presenting a tool of the type mentioned above and having a hard material tip so designed that the characteristics mentioned above are achieved. The aim of the invention is realized by a tool having the characterizing features of the appending claims. Below embodiments of the invention will be described, reference being made to the enclosed drawings. Figure 1 shows a front view of a portion of a cutter armed with tools according to the invention; Figure 2 shows a side view of the cutter according to Figure 1; Figure 3 shows an embodiment of a hard material tip of a tool according to the invention; and Figure 4 shows a further alternative embodiment of a hard material tip of a tool according to the invention. The cutter disclosed in Figures 1 and 2 is generally denoted by 10 and includes a base member 11 and a holder body 12 welded thereto. The base member 11 is provided with through holes 13 that are intended to receive fastening means by which the holder body 12 is attached to a planing blade (not shown) on a machine for ice-scraping and/or snow clearing of roads. A number of tools 14 are mounted in the holder body 12. The tools 14 have a hard material tip that constitutes the real object of invention of this application. The hard material tip 15 will be described more in detail with reference to Figure 3. The tip 15 is in a conventional way brazed to the tool 14 by having a projecting portion 18 received in a correspondingly designed recess 19. The hard material tip 15 discloses in the embodiment according to Figure 3 a cylindrical portion 20 located nearest to the tool. In the area of the free end of the tip 15 the cylindrical portion is transferred into a shape-defining surface 21 having a fixed radius of curvature R₁, in an axial plane through the axis 16 of rotation. Said shape-defining surface 21 is in its turn transferred into a shape-defining surface 22 that has an extension perpendicular to the axis of rotation 16 of the tool 14. Due to the fact that the portion 20 of the hard material tip 15 that is located nearest to the tool 14 has a cylindrical shape the contact point 23 between the hard material tip 15 and the road surface 17 will be located far away from the axis 16 of rotation, relatively seen. This means that a relatively seen lower force is needed to rotate the tool 14 around its axis 16 of rotation. A characterizing feature of the hard material tip 15 according to the invention is that the diameter D of the cylindrical portion 20 only is slightly smaller than the diameter D₁ of the adjacent portion of the tool 14. The tip 15 thus holds a relatively seen great volume of hard material. The location of the contact point 23 relative to the axis 16 of rotation depends on several factors. The above-mentioned relatively seen great volume of hard material is of course one factor as well as the radius of curvature of the shape-defining surface 21 and the inclination angle α of the axis 16 of rotation relative to the road surface 17. Generally seen it is valid that the smaller radius of curvature R₁ the further away from the axis 16 of rotation the contact point 23 will be located. However, it is also important that the radius R₁ is that big that risk for penetration of the tip 15 into the road surface 17 is eliminated to the utmost possible extent. In the embodiment according to Figure 3 the ratio between the radius R₁ and the diameter D is about 1:3. The angle α that the axis 16 of rotation has relative to the road surface 17 is preferably about 40°. One great advantage of the hard material tip 15 according to the invention is that the degree of freedom for variation of the angle α is high. This is at once realized by studying Figure 3. When the angle α is increased the distance from the contact point 23 to the axis 16 of rotation is increased. The embodiment according to Figure 4 is characterized by the slightly conical portion 20″ that widens in direction towards the free end of the hard material tip 15″ that includes a first shape-defining surface 21″ nearest to the conical portion 20″ having a radius of curvature R₁″ in an axial plane through the axis 16 of rotation and a second shape-defining surface 22″ having a radius of curvature R₂ in an axial plane through the axis 16 of rotation. The free end of the hard material tip 15″ is thus combined of shape-defining surfaces 21″, 22″ having different radius of curvature in an axial plane through the axis 16 of rotation. In the embodiment according to Figure 4 the radius of curvature R₂ is essentially bigger than the radius of curvature R₁″. The conicity of the portion 20″ is designated in Figure 4 by β. A value for β in the range of 0 - 5° seems preferable. Indeed the design according to Figure 4 gives rise to a greater stress upon the brazed seam between the tip 15″ and the tool 14 but also a higher readiness to rotate and a greater volume to wear is achieved. For all the described embodiments it is valid that the hard material tip 15;15″ is symmetric as of rotation in respect of its axis 16 of rotation. Also the cylindrical or slightly conical portion 20;20″ should have an axial extension in the range of 0.25 - 0.7, preferably 0.35 - 0.45, times the diameter D of said portion 20;20″ at the connection to the tool 14. To sum up a hard material tip 15;15″ according to the present invention gives rise to essential advantages in ice-scraping and snow clearing. Apart from principally eliminating the risk of penetration into the road surface 17 a relatively seen small force is required to rotate the tool as well as a relatively seen greater volume to wear is achieved. The invention is of course not in any way restricted to the embodiments described above but the different cylindrical and slightly conical portions can be combined with different types of free ends. Thus the invention can be varied freely within the scope of the appending claims.

Claims: 1. Tool intended to be rotatably mounted in a cutter, said tool (14) is in operative position carrying out ice-scraping and/or snow clearing of a road surface (17), and that the longitudinal axis (16) of rotation of the tool (14) forms an angle (α) relative to the road surface (17) that is in the interval of 20° to 90°, and that a hard material tip (15;15″) of the tool (14) contacts the road surface (17) in operative position of the tool (14), that the hard material tip (15;15″) includes a nearest to the tool (14) located cylindrical or slightly conical portion (20:20″), and that the free end of the hard material tip (15;15″) includes shape defining surfaces being symmetrical relative to the axis of rotation (16) of the tool (14), characterized in that a first one (22;22″) of said shape defining surfaces covering the axis of rotation (16) of the tool (14), said first shape defining surface (22;22″) being planar or having a certain radius of curvature (R₂) in an axial plane of the tool (14), a second shape defining surface (21;21″) surrounding and being continuous with said first shape defining surface (22;22″), said second shape defining surface (21;21″) having a certain radius of curvature (R;R″) in an axial plane of the tool (14), said radius of curvature (R;R″) being smaller than the radius of curvature (R₂) for said first shape defining surface (22;22″), and that the axial extension of the cylindrical or slightly conical portion (20:20″) is in the range of 0.25 - 0.7 times the diameter (D) of said portion (20;20″) at its connection to the tool (14). 2. Tool according to claim 1, characterized in that the second shape-defining surface (21;21″) has a radius of curvature (R;R₁″) in an axial plane that is smaller than the diameter (D) of the cylindrical or slightly conical portion (20:20″) at its connection to the tool (14). 3. Tool according to claims 1 or 2, characterized in that the diameter (D) of the cylindrical or slightly conical portion (20;20″) at its connection to the tool (14) is somewhat smaller than the diameter (D₁) of the tool (14) at its end directed towards the hard material tip (15;15′). 4. Tool according to anyone of claims 1 - 3, characterized in that the free end of the hard material tip (15) includes a shape-defining surface (22) having an extension substantially perpendicular to the axis (16) of rotation of the tool (14). 5. Tool according to anyone of claims 1 - 3, characterized in that the free end of the hard material tip (15′) is cap-shaped. 6. Tool according to anyone of claims 1 - 5, characterized in that the conical portion (20″) has a widening shape towards the free end of the hard material tip (15″). 7. Hard material tip (15;15″) intended to be fastened to a tool blank to create a rotatable tool (14) to be mounted in a cutter for ice-scraping and/or snow clearing, said hard material tip (15;15″) including a portion (18) to be connected to the tool blank, a cylindrical or slightly conical portion (20;20″) and that the free end of the hard material tip (15;15″) in its mounted position on the tool (14) includes shape defining surfaces being symmetrical relative to the axis of rotation (16) of the tool (14), characterized in that a first one (22;22″) of said shape defining surfaces covering the axis of rotation (16) of the tool (14), said first shape defining surface (22;22″) being planar or having a certain radius of curvature (R₂) in an axial plane of the tool (14), a second shape defining surface (21;21″) surrounding and being continous with said first shape defining surface (22;22″), said second shape defining surface (21;21″) having a certain radius of curvature (R;R″) in an axial plane of the tool (14), said radius of curvature (R;R″) being smaller than the radius of curvature (R₂) for said first shape defining surface (22;22″), and that the axial extension of the cylindrical or slightly conical portion (20;20″) is in the range of 0.25 - 0.7 times the diameter (D) of said portion (20:20″) at its connection to the tool (14).

Inventors: NILSSON, ROLAND, SJOEDIN, GOERAN, TIBAECK, BO, Sjödin, Göran, Tibäck, Bo
Applicants: SANDVIK AKTIEBOLAG
Application year: 1988
Main classification: E01H5
IPC codes: E01H5