Abstract:
A side trimmer made from hardened steel has an inner diameter with a keyway, an outer diameter, and two faces. A recess is machined in the faces to a radius greater than the keyway root. The recesses enable the faces to be hard faced with a ceramic tool without the tool being destroyed by interrupted cuts at the keyway. At least one face is formed with an annular groove that separates the faces into inner and outer faces. The outer face cooperates with the outer face of a second side trimmer to form a nip that trims a moving coil. When the outer faces have worn, they are resharpened by hard turning with a ceramic tool.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention pertains to metal cutting, and more particularly to apparatus for trimming metal coils. 
     2. Description of the Prior Art 
     An essential step in producing sheet metal in coils is the trimming of the coil edges as it leaves the rolling station. Various equipment has been developed to perform the trimming operation. Such equipment includes pairs of cooperating rotary trimmer blades. The trimmer blades may be in the form of cylindrical disks having flat faces and sharp corners between the disk faces and the outer diameters. For satisfactory operation and long life, the trimmer blades are made of hardened steel. 
     The manufacture of prior trimmer blades is somewhat inefficient. That is because the manufacturing process requires a surface grinding operation on the blade faces. The surface grinding operation is time consuming and requires the use of specialized and expensive machine tools. Further, prior manufacturing methods require grinding of the outer periphery, which necessitates the use of a second grinding machine. 
     In operation, the trimmer blades are placed with their faces parallel to each other. Their peripheries overlap a slight distance with minimal clearance between the overlapping faces such that the faces lie in a common plane. The blades rotate in opposite directions, and their overlapping faces form a nip through which a margin of the metal coil passes. As the coil passes through the nip, the coil is sheared along the common plane. 
     After extended service, the trimmer blades begin to dull. The sharp corners become rounded and eventually lose their cutting ability. At that time, the trimmer blades are removed from service and are resharpened. 
     Because of the hardness of the trimmer blades, resharpening prior trimmer blades presents a problem. Their faces must be ground, but many sheet steel mills which make coils do not have surface grinding equipment. Consequently, prior art dull trimmer blades must be sent to the manufacturer for resharpening, which results in undesirable shipping and handling costs. Repeated surface grinding of these blades reduces the thickness of the blade hub. Hence, spacers may be required if there is not adequate thread length on the arbor. In addition, resharpening the trimmer blades at the factory by surface grinding is a slow and expensive operation. 
     Thus, a need exists for improvements in the field of trimmer blades. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a coil side trimmer is provided that is more economical to manufacture and resharpen than prior trimming equipment. This is accomplished by designing the side trimmers to be manufactured and resharpened by hard turning rather than by grinding operations. The hub of the trimmer blade is not turned or ground when resharpened. 
     The side trimmer has the general shape of a hollow cylinder with parallel faces. They range in size up to two and one-half inches thick. The internal diameter is sized to fit over a standard coil trimming arbor that drives the side trimmer by means of a key. The faces of the side trimmer make sharp corners at their respective junctions with the outer diameter. For maximum strength and rigidity, the side trimmer has substantial thickness. 
     The side trimmer is made from a hardenable steel. The manufacturing process includes rough machining the side trimmer prior to hardening, and finish machining takes place after hardening. It is a feature of the present invention that finish machining of the faces and outer diameter is achieved by hard turning using a ceramic tool rather than by surface and external grinding. To enable such hard turning, the side trimmer is designed with a recess or undercut in each face surrounding the internal diameter. Each recess has a radius that is slightly greater than the distance from the side trimmer axis to the keyway root. The recesses are machined into the respective faces before hardening, and they are deeper than the thickness of the material on the faces that is removed at finish machining. Consequently, the side trimmer face areas outside of the recesses can be finish machined in a continuous cut with a ceramic tool, and the probable destruction of the ceramic tool by an interrupted cut due to the keyway is eliminated. 
     Further in accordance with the present invention, the side trimmer is designed to be resharpened in the field rather than at the manufacturing plant. For that purpose, at least one and preferably both faces of the side trimmer are formed with an annular groove so as to divide the face into inner and outer faces. The outer face has a sufficient radial width to properly overlap the outer face of a cooperating side trimmer to trim the edge of a web or coil of sheet metal. 
     After the outer faces of the cooperating side trimmers have worn because of use in trimming the coil metal, the side trimmers are removed from their arbors for resharpening. The side trimmer outer faces are hard turned on a lathe at the mill with a ceramic tool. Rough turning may be required with a carbide tool if trimmer surfaces are rough as a preliminary step. The grooves are designed to enable the use of a four-sided ceramic tool with a lead angle for the hard turning operation. In that manner, not only is the prior requirement of returning the side trimmer to the factory for resharpening eliminated, but the possibility of ceramic tool failure during the hard turning resharpening process is greatly reduced. 
     The annular grooves permit reducing the thickness of the side trimmer only near the outer diameter because of sharpening. A side trimmer can be resharpened until the outer face reaches the level of the root of the annular groove. The depth of the groove is designed so that the side trimmer still has ample rigidity as it nears the end of its useful life. When both outer faces have been resharpened a number of times such that they have reached the level of the roots of their respective annular grooves, the side trimmer is recycled or discarded. 
     In a modified embodiment of the invention a second set of annular grooves of a smaller radius are provided to afford a second zone for resharpening. This further increases the life of the trimmer. Other objects and features of the invention will become apparent from the disclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a pair of side trimmers, each of which embodies the features of the invention, with the side trimmers installed for trimming coil metal; 
     FIG. 2 is a top view of the trimmers taken generally along line 2--2 in FIG. 1; 
     FIG. 3 is a rear sectional view of the trimmers taken generally along line 3--3 in FIG. 2; 
     FIG. 4 is a side view of the side trimmers taken generally along line 4--4 in FIG. 3; 
     FIG. 5 is an enlarged side view of one of the side trimmers of the present invention; 
     FIG. 6 is a cross-sectional view of one of the side trimmers taken along line 6--6 of FIG. 5; 
     FIG. 7 is a cross-sectional view similar to FIG. 6, but showing the side trimmer after having been resharpened; and 
     FIG. 8 is a cross-sectional view similar to FIG. 6, but showing a modified embodiment of the side trimmer that also embodies the features of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto. 
     Referring to FIGS. 1 to 4, a pair of side trimmers 1 are illustrated that include the present invention. As FIG. 1 shows, the side trimmers are particularly useful for trimming the edge 3 of a thin gauge coil 5 of metal, typically a coil of steel. The invention, however, is not limited to metal cutting operations. 
     In the particular application of the side trimmers 1 shown in FIGS. 1 to 4, a conventional web or coil 5 of metal or steel or similar material is formed by rolling equipment as is known in the art and is not shown. The coil 5 is fed in the direction of arrow 7 (see FIG. 1) by auxiliary well known means, which is not illustrated. The coil has rough edges 3 as it leaves the rolling equipment. 
     In accordance with the present invention, the opposite edges 3 of the rolled coil 5 are trimmed by the side trimmers 1 to be straight and at a specified distance apart; a finish edge is represented by reference numeral 9. As a part of the trimming process, a strip 11 of trim scrap is produced along the coil edge. Coil trimming is achieved by passing an edge 3 through a nip 13 formed by two overlapping side trimmers (as best shown in FIG. 3). 
     Each side trimmer 1 is rigidly but removably mounted to a respective arbor 15a and 15b. Driving of the side trimmers on the arbors 15a and 15b is by respective keys 17a and 17b. The direction of rotation of the arbors is indicated by arrows 19a and 19b (see FIGS. 1 and 4). 
     In the preferred embodiment (and please refer now to FIGS. 4 to 6), each side trimmer 1 is constructed as a hollow cylinder having an outer diameter 21, an inner diameter 23, and opposed faces 25 which extend from the recess 29 to the outside diameter or periphery 21. Representative dimensions for an exemplary side trimmer are approximately 16 inches for the outer diameter 21, 8.50 inches for the internal diameter 23, and a nominal thickness of approximately 1.50 inches between the two faces 25. A keyway 27 formed in the inner diameter 23 may be approximately 1 inch wide and 0.50 inches deep. The side trimmer is made from a high quality hardenable steel such as AISI H13 tool steel. 
     It is a feature of the present invention that the side trimmer 1 is manufactured by a process that avoids grinding of the outer diameter 21 and the faces 25. For that purpose, the manufacturing process starts with the operation of sawing a blank of material from a length of solid or hollow forged bar stock. Individual forgings, either disks or rings, may be substituted for a sawed piece of solid or hollow forged bar stock. The blank is chucked in a lathe, where it is drilled and/or bored to a rough dimension for the inner diameter 23. One face 25 is rough turned on the lathe, and a recess 29 is machined in the face. An annular groove 32 is also cut in the face. As FIG. 8 shows, a second annular groove 66 may also be cut into the face at this time. The blank is reversed in the lathe, so face 25, recess 29 and groove 32 can be machined in the opposite face. The second annular groove 66 may also be cut in the face at this time. The outer diameter 21 is turned. The keyway 27 is then cut in the internal diameter. The root, i.e., the deepest surface 31 of the keyway is closer to the side trimmer axis 33 than the radius 30 of the recess. The blank is then hardened and tempered to approximately 54-56 Rockwell C. After the heat treat operation, one face 25 is hard turned with a ceramic tool. Then the inside diameter 23 of the hole is ground to the finished size locating off the hard turned face 25. The other face 25 is then hard turned and finally the outside diameter is hard turned to size. 
     Unlike prior trimming blades, the faces 25 and outer diameter 21 of the semi-finished side trimmer 1 are not ground to bring their respective dimensions to finish size. Rather, the outer diameter and faces are hard turned in a lathe with a suitable ceramic turning tool, such as are manufactured by Kennametal Company of Latrobe, Pennsylvania. One face is hard turned by a suitable ceramic facing tool to create one of the sharp corners 39 at the junction of the face and outer diameter. The presence of the recess 29 in the face enables the hard turning operation to be performed without requiring the ceramic tool to contact the keyway 27, which would destroy the ceramic tool by the resulting interrupted cut. After grinding the internal diameter 23, the side trimmer is reversed in the lathe chuck and the second face is hard turned so as to create the other sharp corner 39. The side trimmer is complete and ready for installation on an arbor 15a, 15b. 
     As mentioned, the side trimmer 1 is provided with a groove 32 in each face 25. Each groove divides its associated face into an outer face 37 and an inner face 38. The grooves are located on the side trimmer such that the nip 13 between cooperating side trimmers occurs exclusively on their respective outer faces 37. The purpose of inner and outer face construction is to greatly simplify and economize the process of resharpening the side trimmers. Periodic resharpening is required because the corners 39 and the outer faces 37 of the mating side trimmers gradually wear as they trim the coil steel 5 passing through the nip. With prior trimming blades, surface grinding the faces 25 was required to resharpen the corners 39 and the faces. However, most steel rolling mills and similar facilities do not have surface grinding equipment. With the division of the face into inner and outer faces, the side trimmer can be resharpened at the mill merely by chucking it in a lathe and hard turning with a ceramic tool across the outer face 37. If the faces are rough as a result of wear a preliminary turning can be done with a carbide cutting tool. If necessary, the outer diameter 21 can be hard turned a slight amount. Since most steel rolling mills have lathes, the side trimmers can remain there, thereby saving the time and expense of both the surface grinding operation and the shipping to the manufacturer and back. 
     The grooves 32 are located and dimensioned such that reducing the thickness of the side trimmer 1 between the faces 37 through resharpening does not adversely affect its overall strength and rigidity. With a nominal thickness of 1.50 inches for the side trimmer, a satisfactory depth for each groove 32 is approximately 0.38 inches. We have found that a width of approximately 0.25 inches for the grooves 32 works very well. That width enables the outer faces 37 to be resharpened with a four-sided ceramic tool having a lead angle, so the initial cutting of the tool can be made with the tool&#39;s edge rather than its point. That procedure greatly reduces the possibility of ceramic tool failure. 
     FIG. 7 shows a side trimmer of 1.50&#34; that has been resharpened on both outer faces 37 to leave faces 37&#39; with corners 62. If desired, of course, the side trimmer can be manufactured with only one groove 32 and thus resharpened on only one face 37. Resharpening can be repeated until the outer faces 37&#39;  reach the levels of the roots 41 of the grooves 32. At that point, the side trimmer has reached the end of its useful life. The depth of the grooves 32 is chosen such that sufficient strength and rigidity are present at the outer face for proper trimming of the coil steel 5 even when the outer faces reach the level of the groove roots 41. 
     FIG. 8 shows a modified embodiment of the invention in which a second groove 66 is provided to provide an additional cutting zone 60 after the outer cutting zone 69 is worn down. The remaining portions of faces 37&#39; of FIG. 7 are removed to the roots 41 of grooves 32 with a ceramic tool moved in the direction of arrow 71. The new outer diameter 81 is then formed by a final pass of the cutting tool parallel to the axis of the arbor by turning with a ceramic tool in the direction of arrow 71. With use of the FIG. 8 embodiment, the faces 60 can then be hard turned as required to maintain a sharp cutting edge. 
     Thus, it is apparent that there has been provided, in accordance with the invention, a method of making new side trimmers and side trimmer blades that fully satisfy the aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. 
     Although the present invention is described in association with ceramic tools, any other tool developed in the future with ability to turn tool steel or high speed steel hardened to Rockwell 56 C. to 62 C. can be employed to obtain the benefits of the invention. The use of the term &#34;ceramic&#34; in the claims is intended to encompass all tools which could be employed in the method described herein. Various cutting tool materials have been disclosed in the last few years which may be adapted for use in practicing the invention. These patents are included in the following: U.S. Pat. No(s) 4,849,381; 4,852,999; 4,867,761; 4,770,673; 4,441,894; 4,440,547; 4,449,989; 4,421,525; 4,431,431; 4,406,667; 4,388,085; 4,409,003; 4,409,004; 4,416,670; and 4,406,668.