Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28D—WORKING STONE OR STONE-LIKE MATERIALS
  • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
  • B28D1/18—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by milling, e.g. channelling by means of milling tools
  • B28D1/186—Tools therefor, e.g. having exchangeable cutter bits
  • B28D1/188—Tools therefor, e.g. having exchangeable cutter bits with exchangeable cutter bits or cutter segments

Definitions

• the invention relates to a tool for the working of hard materials, for example subsurfaces, rocky ground, asphalt, oil gravel or concrete, and which consists of a holder, preferably in the form of a substantially round shank designed to be mounted in larger numbers on a rotating element, in that the round shanks are secured freely rotatable around their longitudinal axes in bores in the rotating el ⁇ ement, preferably with the axes at an angle to both the tangential and the radial direction, and where in each of the round shanks there is fitted a cutting element of hard metal in a central blind hole in the end of the shank.
• the object of the present invention is thus to prov- ide other means of extending the lifetime of the cut ⁇ ting element, in that the overall costs of operating with such tools are, on the whole, proportional to the lifetime.
• the tool according to the invention is characteristic in that contact surfaces of the cutting element are formed in such a manner that the lowest part of the blind hole's side surfaces is free, i.e. they do not engage with the cutting element during mounting or when the first period of use has taken place, and that the cutting element is hereby pressed into the shank.
• the holder and the cutting el ⁇ ement are dimensioned in such a way that there is air under the cutting element after the pressing in.
• the pressing in takes place upon mounting and during use, which involves the influence of an axially-directed force component which results in a further pressing in. It is important, however, to emphasize that the dimensioning is effected in such a manner that the cutting element is not pressed in to the bottom after its first period of use, and neither after the wear ⁇ ing down of the first part.
• OMPI element is conical. A further pressing down during the work will thus result in the cutting element com ⁇ ing to sit even more firmly. This, of course, is of immediate importance when the work and the consequent wearing away of the extreme ends of the shank has - ⁇ brought about the opposite effect. It is obvious that the same effect can be achieved if the blind hole is conical or both parts are conical, and one embodiment is thus characteristic in this respect. According to the invention, the half cone angle can be approx. 3 .
• blind hole is less conical than the cutting element, the result being that the frictional forces which secure the cutting element will, to a higher degree, be concentrated at the extreme end of the shank, whereby the resistance moment which opposes the for ⁇ ces which seek to break the cutting element out of its seating will be greater.
• the distribution of force will be reversed because of the elasticity in the holder, in that there will be more holding mater ⁇ ial surrounding the lower part of the cutting elem ⁇ ent.
• OMPI OMPI Moreover, the costs of manufacture are much less, the reason being that it is far cheaper to drill a cylin ⁇ drical hole than a tapered hole.
• the cutting element can be made conical as a matter of course, the reason being that it is pressed by powder pressing. Further ⁇ more, it is cheaper and easier to produce a conical cutting element than a cylindrical cutting element.
• Another embodiment is characteristic in that the bot- torn of the blind hole is provided with a second cen ⁇ tral blind hole (of smaller diameter) , and that the bottom end of the cutting element is formed with a guide stud, or that to its bottom end there is se ⁇ cured a guide stud which fits down into the second bottom hole, hereby enabling the lifetime of the cut ⁇ ting element to be further extended.
• the cross-section of the guide stud is an equilateral polygon, for example an equi ⁇ lateral hexagon, and that it is soldered firmly to the cutting element, in that it projects into the central bottom hole in the cutting element. It is hereby possible to achieve a good soldered connection between the guide stud and the cutting element, while at the same time the guide stud retains its charact ⁇ eristics as such in a cylindrical hole.
• the tool according to the invention can be characteristic in that the fit between the guide stud and the second blind hole is a press fit.
• a guide stud which does riot give any play, but which still allows itself to be pressed deeper down into the hole. This applies particularly if the cross-section is an equilateral polygon.
• fig. 1 shows one embodiment of a tool accord ⁇ ing to the invention, seen from the side and with the shank in longitudinal section,
• fig. 2 is a longitudinal section of the outer end of a holder according to a second preferred embodiment, and with a cut- ting element shown with stippled lines during its insertion into the holder,
• fig. 4 shows the holder from fig. 1 after the wearing down of the cutting element.
• the latter gives a rotation of the holders around their longitudinal axes.
• a conical bottom hole 2 with a half cone angle of 3°.
• a similarly conical cutting element 3 of hard, wear-resistant pressed -.
• the top end of the cut ⁇ ting element is provided with a conical surface 4, so that a generatrix in the cone surface is directed in the tangential direction.
• the cone surface thus already has the shape that it will assume on being worn down.
• the lower part of the cutting element 3 is provided with a bottom hole 5 with a semi-spherical bottom, and having sides formed with slip.
• the cut ⁇ ting element is produced by powder pressing, and the semi-spherical surface is necessary for generating sufficient pressure in the mould. If this pressure was not achieved, the outer conical surface would be given a slight indentation, i.e. it would be slightly concave or hourglass-shaped.
• the bottom hole 5 serves to secure a piece of hexagon bar steel 6 which, by soldering, brazing or welding, is fastened centrally in the hole 5 to form a guide stud 6 which, with its largest cross dimension, forms a press fit in a sec ⁇ ond central bottom hole 8, the bottom end of said guide stud 6 being provided with a bevel 9.
• Fig. 2 shows a holder 11 according to a preferred em- bodiment.
• a blind hole 12 is cylindrical at its low ⁇ est part, but has a conical part or bevelling 13 above, so that a conical cutting element 14 indicated by the stippled lines and, for that matter, identical to that shown in fig. 1, can be inserted in precisely this part of the hole.
• the holder 11 and the cutting element 14 are placed in a press capable of exerting a pressure of 5 - 10 tons.
• the cutting element is then pressed in to the position shown in fig. 3, whereby the holder 11 is deformed, in that annular stresses arise which by friction se ⁇ cure the cutting element.
• the annular stresses will be greatest at the bottom be ⁇ cause of the shape of the holder, the reason being that the thickness of the material around the blind hole 2 increases downwards, and the deformations as a result hereof become smaller downwards.
• the conicity of the blind hole is less than the conicity of the cutting element, which in principle can also be said to be the case for the construction with regard to figs. 2 and 3, with a suitable choice of conicities one can ensure that the annular stresses are greatest at the top. This natur ⁇ ally gives a greater power of resistance against non -central outer forces on the cutting element.
• Fig. 3 with the shown position of the cutting element 14 is that position which the parts have when the holder is mounted and ready for use. The cutting element will remain in this position for a very long time. Approximately the upper third part of the cutting el ⁇ ement will first be worn away, though the cone shape at the top will be retained for reasons of the above- mentioned angles chosen in the mounting. The angle in fig.
• the cutting element is made of hard metal, the holder or shank of hardened chrome-nickel steel of the type 34 Ch Ni Mo 6 , and the guide stud of so-called mach ⁇ ine steel, for example steel 37.
• the cutting element will fall out as soon as it is worn down to approx. half its size.
• the present preferred embodiment there will be only very little of it remaining when it falls out, see fig. 4.
• the guide stud does not constitute a necessary prerequisite in achieving the new technical effect.

Landscapes

• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Earth Drilling (AREA)
• Road Repair (AREA)
• Cutting Tools, Boring Holders, And Turrets (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8127043

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (2)

Family Cites Families (4)

• 1982
  • 1982-08-26 DK DK381382A patent/DK381382A/da not_active Application Discontinuation
• 1983
  • 1983-08-24 EP EP19830902751 patent/EP0119213A1/en not_active Withdrawn
  • 1983-08-24 GB GB08408942A patent/GB2136730A/en not_active Withdrawn
  • 1983-08-24 DE DE19833390200 patent/DE3390200T1/de not_active Withdrawn
  • 1983-08-24 WO PCT/DK1983/000078 patent/WO1984000987A1/en not_active Ceased
  • 1983-08-24 AU AU18900/83A patent/AU1890083A/en not_active Abandoned

Non-Patent Citations (1)

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