Apparatus for removing burr by multiple-stage grinding machine

Abstract: This apparatus has plural fixed grinding machines (10,11), which are installed along the direction of travelling line of billets (1). And, facing pair of grinders (3,4) are equipped in a manner that the distances between each facing pair of grinders (3,4) are gradually shorter along the travelling direction of the billets (1) from the upstream side to the downstream side. In such a multiple-stage grinding machine, the burr on the welded part of the top and bottom side of the billet (1) are ground sequentially by the grinders (3,4), and the burr on welded part of the right and left side of the billet are ground sequencially by the grinders (3,4).

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus for removing burr on a welded part in a billet where billets are joined together by a flash butt welding in a continuos rolling process. An example of such an apparatus is disclosed in EP 761 331 A. 2. Description of the Related Art In the continuous rolling process, the successively casting billets are joined together at the inlet of a rolling mill, making use of the flash butt welding method. And then, a continuous billet can be formed. Finally, the continuous rolling process, what we call, Endless Rolling Process, can be obtained. However, the said process has an possibility to bring about an uplifted welded part with spills (which are caused by untrimmed laminated part line) and other defects. As the result of it, the as-welded billet has been rolled without any corrective action. No satisfactory product can be produced in such a way, from a view point of the product quality. Consequently, the burr on the welded part is in need of being removed before being bited by the rolling mill. In case of a square billet, a burr-removal apparatus has been disclosed in 'unexamined Japanese patent publication No. 52-43754, examined Japanese patent publication No. 57-11722. '. Such a disclosed burr-removal apparatus utilizes formed turning tools or those which are faced each other against its opposite side, in order to remove the said burr on the welded part. This apparatus has, however, disadvantages of suffering severe abrasion on the turning tool and of spending a lot of time on exchanging the turning tools. By that reason, this apparatus is not suitable for being applied to the continuous rolling process under the usual operating condition of 24 hours continuously. Furthermore, a method has been known to grind burr on the welded part by a grinding machine, syncronizing the grinding machine with the travelling billet. (unexamined Japanese patent publication No. 9-66 450, unexamined Japanese patent publication No. 9-122918). However, such a method needs for letting the grinding machine travel, simultaneously with the travelled billet itself, for a required time (3-10sec.) to be grinded. It causes some problems of the concerned space-arrangement and its instrumentation control system. But, in such a continuous rolling process for billets, the grinding method is the most suitable for removing burr on the welded part because of satisfying severe operative rolling condition. In such a case, under the condition of using the travelling grinding machine, the large space for travelling is required. In addition, the complex instrumentation control system is required for synchronizing the grinding machine with travelling speed of billet. On the other hand, the fixed grinding machine does not require large space nor complicated control system, but taking the grinding capacity into consideration, a single-stage grinding method cannot deal with the whole of the successively occurring welded parts. JP 05 277 916 A describes a method for grinding a weld overlay to prevent excessive grinding which lowers the welding strength, and to attempt abrasion prevention and life prolonging of the grinding wheel. In a first step the grinding wheels are positioned to grind the left side of the boundary of a weld overlay. In a second step the same procedures are applied to the second boundary part of a weld overlay. Finally, the middle part of the weld overlay is grounded by positioning the grinding wheels above and below the surfaces. SUMMARY OF THE INVENTION It is an object of the the present invention to provide an apparatus of a multiple-stage-grinding machine for removing burr on the welded part of the billet with small sized grinders to save space and much-simplified control system. This object is achieved by the apparatus of claim 1. The plural fixed grinding machines are equipped in a manner that the distances between the each pair of grinding machines, which are facing each other between the upper side and the bottom one of a billet, and between the left side and the right one of the billet, are gradually getting shorter, along the travelling direction of a billet from upstream to downstream. So, the burr on the welded part are ground stepwise in a manner that the continuous billets are passing through each pair of grinders. Therefore, the load on each grinders can be reduced without unreasonable force to the billets. Furthermore, the small size of the grinders makes it possible to save space for the apparatus. No need for travelling the grinding machines makes it possible to control the apparatus in a simple way. Optionally because the axes of the grinders of the plural fixed grinding machines are located in a inclined position against the transferring line, the contacting time with billet and the retreival time for billet can be kept longer. Consequently, the grinded powder from the burr can easily be dumped, because it cannot be splashed on the billets and on the neighboring grinding machines. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic drawing showing a multiple-stage-grinding method, which exhibits the burr on the welded part in the billet before being dealt with the multiple-stage-grinding machine. FIG. 1B is a schematic drawing showing a multiple-stage-grinding method, which exhibits the situation when the welded billet is passing at the first-stage in the grinding procedure. FIG. 1C is a schematic drawing showing a multiple-stage-grinding method, which exhibits the situation when the welded billet is passing at the second-stage in the grinding procedure. FIG. 2 is a top view of an apparatus for removing burr by multiple-stage grinding machine. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1A, FIG. 1B and FIG. 1C show the schematic drawing of a multiple-stage grinding method. There is uplifted welded burr 2 on the jointed part of the billets which are welded and joined together by travelling flash butt welding apparatus in the preceding process. In this example, two fixed grinding machines 10 and 11 are installed in the transferring direction of billet 1. And, the distance B between a pair of top and bottom grinder 4 at the second step is set to be smaller than the distance A between a pair of top and bottom grinders 3 at the first step. Because the depth to be ground in each step is set to be almost constant, the burr 2 on the welded part is ground stepwise so as to the height of the burr becomes lower sequencially and the level of burr 2 is almost equal to the surface of billet by passing billet 1 through the first step and the second one of the fixed grinding machines sequentially. In such a way, the burr on the welded part of top and bottom side has been ground, and then, the burr on the welded parts of the right side and left one are ground and removed in the same process as the multiple-step grinding machines. The outer diameter of grinders at each step is designed to be the same value. The dimension of the outer diameters is, also, designed to be as small as 300 to 400 mm, in order to make the said apparatus into a smaller size. The effective width of the grinders is a little bit wider than one edge of a billet. Furthermore, the axes of the grinders are preferable to be installed in a inclined position of 30-45 degrees against the direction of transferring line of a billet. By the reason of such a inclination, the grinded faces get in contact with the burrs on the welded faces, diagonally. Consequently, the contact time and grinding time with inclination can be longer than those without inclination. The grounded powder from the burr can easily be dumped by the reason of splashing the grounded powder from the burr at some degree toward the billets. Furthermore, such a grinding can be achieved in a moment, so that it enables a motor of the grinding machine to be much smaller, making use of a fry-wheel. Therefore, it makes it possible to keep space for the whole apparatus small even when it is a multiple-stage-grinder. In addition, no need of travelling the grinding apparatus makes it possible to keep a rotation speed of the grinders in a constant rate. It, also, makes it possible to simplify the instrumentation control system to a lot of degree. FIG. 2 shows concrete constitution of an apparatus for removing burr by the multiple-stage-grinder. In this figure, 10 is a fixed grinding machine at the first step, and then 11 is a fixed one at the second step for grinding the burr on the welded part of the top and bottom side of billet 1. In the downstream side, a fixed grinding machine 12 at the first step and a fixed one 13 at the second step are installed in the same way, for grinding the burr on the welded part of the right side and left one of billet 1. Although the grinders of the fixed grinding machine 12 and 13 for the right side and left one of billet 1 are graphically designed in parallel with billet 1, the axes of the grinders actually located in a inclined position against the direction of 10 and 11 for the top and bottom side of billet 1. The fixed grinding machine of each step is equipped with a pair of grinders 4 for the top and bottom, and a pair of grinders 5 and 6 for the right side and the left one, respectively. The grinders can be rotated by the grinding motor 7. Furthermore, the distance between in the downstream is set to be smaller than that of the facing pair of grinders 3 for the top and bottom in the upstream. The distance between facing pair of grinders 6 for the right side and left one in the downstream is set to be smaller than that of the facing pair of grinders 3 for the top and bottom in the upstream in the same way. Altough these distances of the grinders can be adjusted automatically by the geared motor 8 for adjusting distance, they can be adjusted manually. Manual adjustment is rather enough and suitable, judging from an point of reducing cost and from the small sized-apparatus and compact one. The operation of the apparatus for removing burr by multiple-stage grinder can be obtained as mentioned above. Describing the operation in detail, at first, the billet 1 welded by the flash butt welding method is transferred to the apparatus. Secondarily, the burr on the welded part of the top and bottom side of billet 1 are ground sequentially by the grinders 3 and 4 of the two fixed grinding machines 10 and 11, in order to make the height of the burr lower. Thirdly, the burr on the welded part of the right and left side of billet 1 is ground sequencially by the grinding stones 5 and 6 of the two fixed grinding machines 12 and 13. After the burr on the welded part are ground, the billet is transferred to the rolling mills to roll the billet continuously. Altough the order of grinding burr on the welded part is from the top and bottom of side to the right and left side of a billet in the above-example, it makes it possible to reverse the order, naturally. Unless otherwise, it makes it possible to grind burr on the welded part of from the top and bottom side and to the right and left side, one after the other. As mentioned above, the present apparatus has plural grinders of the fixed grinding machines installed in a manner that the distances between each facing pair of grinder is gradually shorter along the travelling direction of a billet from the upstream to the downstream and the burr on the welded part is ground stepwise. Therefore, it becomes possible to save large space for the apparatus, in comparison with a tarvelling grinder. By that reason, the instrumentation control system of the apparatus can be simpler. The load on each grinding step can be reduced. The size of the apparatus can be smaller. Unnecessary force can be reduced. Furthermore, the contact time with billet and the retreival time for grinding can be longer. The slag can easily be dumped by installing the axes of the grinders of each grinding step, in an inclined position against the transferring line.

Claims: An apparatus for removing burr on a welded part in a billet (1) where billets are joined together by a flash butt welding in a continuous rolling process, characterized by at least a first fixed grinding machine (10) and a second fixed grinding machine (11); a first pair of facing grinders, which are located in said first fixed grinding machine (10) having a distance A between each facing grinder; a second pair of facing grinders comprising grinding stones, which are located in said second fixed grinding machine (11), having a distance B between each facing grinding stone; the distance B being shorter than the distance A along a travelling direction of the billet (1) from a upstream side to a downstream side. The apparatus of claim 1, wherein said at least two fixed grinding machines (10, 11) have axes of grinders which are located in an inclined position against the direction of the travelling line of the billet (1).

Inventors: FUJII HIROSHI, MATSUO GIICHI, OKUSHIMA KOJI, FUJII, HIROSHI, MATSUO, GIICHI, OKUSHIMA, KOJI
Applicants: NIPPON KOKAN KK, NKK CORPORATION
Application year: 1998
Main classification: B24B9
IPC codes: B23K11, B24B5, B24B27, B24B9, B21B15, B21B45, B23K37