Patent Abstract:
The invention relates to a composite system for a cut-off wheel. The cut-off wheel includes an abrasive external cutting ring with depressions on both sides in the vicinity of the bore and two flush-fitting tensioning plates placed in the depressions to act as a core clamping device. The clamping plates are reusable elements, retained by the user, and transfer forces to the clamping flanges of the machine. The plates also increase stability and reduce waste.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a U.S. National Stage of International Patent Application No. PCT/AT2005/000413 filed Oct. 18, 2005, and claims priority under 35 U.S.C. §119 of Austrian Patent Application No. A 1749/2004 filed Oct. 19, 2004. Moreover, the disclosure of International Patent Application No. PCT/AT2005/000413 is expressly incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant invention relates to the composite system for a synthetic resin-bonded cut-off wheel with an outer diameter of greater than or equal to 400 mm and, in particular, to a synthetic resin-bonded cut-off wheel having a cutting ring with depressions and two adapted edge-shaped clamping plates inserted into the depressions as reusable core clamping devices. 
     2. Discussion of Background Information 
     Synthetic resin-bonded cut-off wheels starting at a diameter of greater than or equal to 400 mm are used at stationary separating facilities in the metal-generating and metal-processing industry, to cut steel, cast iron, special alloys, inconell, titanium, etc. 
     The generally slight usability of conventional cutting wheels is a great disadvantage. In an ideal case, homogenous cut-off wheels can be used up to a minimum of 45% of the new diameter, but on average they can only be used up to 60% of the initial diameter, however, these figures depend on available machines as well as large material measurements. 
     Once used, the remaining residual discs must be disposed of at high costs according to national disposal guidelines. Another disadvantage is the use of raw material for the unused core zones in the cut-off wheel, which results in additional costs for the raw material sector despite the availability of alternative abrasive grain materials for reinforcement and resin portions of a cut-off wheel. 
     European Patent 0 832 720 A2 describes a synthetic resin-bonded fabric-reinforced cut-off wheel by means of a non-positive bonding on a metallic base body. This system, however, was not able to establish itself because a small residual film of the grind-active edge zone remains on the base of the body. Therefore, the need to dispose of a metal core comprising a synthetic resin-bonded residual film still remains. 
     A further solution is described in EP 0 769 352 A1, wherein the grind-active edge zone is pressed on a metallic base body in a non-positive manner during production. The high-priced acquisition of a large number of these base bodies has turned out to be a disadvantage. In addition, there is a logistical problem when returning the used composite cutting wheel, which must be sent back to the manufacturer to be re-plated. Thus, for cost reasons, this system can only be used at a limited distance to the manufacturer. In addition, the cleaning and re-plating associated with the cut-off wheel requires a greater technical effort, time, and cost. 
     BRIEF SUMMARY OF THE INVENTION 
     An aspect of the instant invention is to create a composite system, which eliminates the above-mentioned disadvantages and makes it possible for the user to deplete the external cut-off wheel up to 95% of the entire grind-active cutting ring surface, and further ensures additional advantages such as a reduced cutting wheel width and increasing stability. 
     According to the invention, this aspect is achieved by synchronizing the bore diameter of the cut-off wheel to the minimum depletion diameter and pressing the edge form of the two clamping plates, which are offset on both sides, into the depressions. This enables a virtually complete depletion of the grind-active edge zone, and only a small abrasive residual ring must be disposed of. 
     The two clamping plates, which are to be considered to be connecting elements between the actual clamping flanges at the machine side and the grind-active cutting ring, are essential components of this invention. Because the transition from the clamping flange to the cutting wheel for conventional products represents a weak spot, this disadvantage is considerably improved according to the invention by the material of the clamping plates, which is possible as an alternative. 
     Due to the fact that the two clamping plates remain with the user, only the considerably lighter cutting ring must be sent to the customer and a weight savings of up to 40% is thereby possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional features and details of the instant invention can be found in the description of the figures below. It is shown therein: 
         FIG. 1  is an exploded illustration of a cut-off wheel with double clamping plates in accordance with the invention; 
         FIG. 2  is a sectional view through the composite system along the line A-A in  FIG. 3 ; and 
         FIG. 3  is a side view of the cutting ring composite system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The cut-off wheel  10  illustrated in the figures is a synthetic resin-bonded cut-off wheel  10 , preferably without additional material reinforcement. However, different degrees of hardness are adapted to respective application requirements and customer requests via a systematic selection of phenolic resin in combination with coordinated abrasive grains and fillers. 
     Corundum, specifically special corundum, zircon corundum, and sinter corundum as well as silicon carbide are used as grinding mechanisms. The fillers comprise raw materials, such as pyrite, zinc sulphide, graphite, potassium chlorine manganate, etc., which are also presently used in cutting wheels for industrial applications. 
     Glass material inserts are presently used as material reinforcement  5 . In the future, however, alternatives such as Kevlar® or carbon fiber are possible. Additionally, an embodiment without a continuous reinforcement is possible. However, reinforcements should be provided in the region of the depressions. 
     The outer diameter D of the cut-off wheel  10  typically lies between 400 and 2000 mm, however, preferably the outer diameter D is greater than 800 mm. Ideally, the bore diameter d of the cut-off wheel  10  can be adjusted to an applied minimum diameter. For manufacturing reasons, however, a fixed bore diameter d should be chosen based on the respective standard measurement of the cutting ring  1 . A range of 40-80% of the outer diameter D is to be indicated as the recommended value for the bore diameter d. 
     Presently, the ratio of the outer diameter D to the width T typically lies in the range of 80-100. According to the invention, due to the considerably stiffer core zone, an increase of up to 130 can be realized. The grind-active cutting ring  1  can be embodied on a parallel plane, as well as in a conical manner, i.e., so as to taper towards the bore region. 
     For clarity reasons, the width T in  FIGS. 1 and 2  is illustrated many times too large in relation to the outer diameter D. 
     On both sides of the flat surface in the bore region, the cut-off wheel  10  encompasses a plurality of geometric depressions (or recesses)  3 , into which the two clamping plates  2  are inserted with an exact fit. The shape of these depressions  3  can be embodied so as to be round, rectangular, but preferably like a dovetail. To enable a good pretensioning of the clamping plates  2 , the depth of these depressions  3  must be between 0.1 and 1 mm, and preferably 0.2 to 0.6 mm less than half of the cutting ring width T in the bore region. The radial reach e of these depressions  3  is a function of the outer diameter D and is between 10 and 200 mm, and preferably between 30 and 60 mm. 
     The two clamping plates  2 , having a defined edge shape, fit exactly into the bilateral depressions  3  of the cut-off wheel  10 , and are a considerable component of this system. In response to being clamped with the conventional clamping flanges  4   a  and  4   b , the two clamping plates  2  are compressed and the required lateral clamping force is thus generated. The drive shaft thereby transfers the forces required for the clamping process to the two clamping plates  2  via the clamping flanges  4   a  and  4   b . From there, the forces are finally transmitted via the special edge shape to the grind-active abrasive cutting ring  1  in a non-positive manner. 
     The clamping plates  2  can be embodied in a straight, offset, perforated or also in a corrugated shape. As a possibility for reducing the weight, the clamping plates  2  can be provided with additional depressions  3 . 
     The depressions  3  of the two clamping plates  2  is characterized by a plurality of symmetrically, round, square, dovetail-shaped, or similarly formed protruding clamping surfaces, which must fit exactly into the bilaterally pressed depressions  3  of the grind-active cutting ring  1 , and which can thus transfer the forces which occur during the abrasive cutting. 
     The total thickness of the two clamping plates  2  must be slight, i.e. approximately 5-10% thinner than the wheel width T in the bore region of the cut-off wheel  10 . In doing so, it is ensured that the required free cutting depth is achieved as with conventional cutting wheels. 
     High-strength reinforced synthetic materials, carbon fibers, non-ferrous metals, special alloys, titanium, but preferably presently simple steel plates are used as material for the clamping plates  2 . In addition to the required basic strength, it is an important criterion for the material to encompass a certain flexibility and high residual stress, so as to be able to withstand the lateral force effects occurring in response to such applications, without permanent damage. 
     To facilitate the handling in response to clamping the composite system, provisions are made in the clamping plates  2  for slits  2   a , into which special tension springs are inserted to aid in clamping. When dealing with very large clamping plates  2  (greater than 60% of the outer diameter of the cutting ring  1 ), additional bores  2   b  can be installed in the outer diameter region of the clamping plates  2  as an additional fixing, or to increase clamping force. Thereby, connecting elements do not protrude beyond the end face of the clamping plate  2 . 
     The position and form-exact pressing of the cut-off wheel  10  into the depressions  3  in the bore region is required. This is achieved by pressing a template having an exact fit. In the alternative, the depressions  3  can also be subsequently ground at a suitable processing facility.

Technology Classification (CPC): 1