For being able at the rolling of continuous cast work- pieces to achieve a good quality of the final product, the workpieces prior to their rolling must be free from defects, i.e. that particularly surface cracks extending more or .less deep must be prevented to a sufficient degree. This is effected in that the workpiece prior to its rolling is scanned or inspected in one way or another in respect of cracks, which thereafter are re- ^• moved by grinding. At present, this surface condition¬ ing is carried out substantially for one or two sides of the workpiece at a time in a separate machining station where the workpiece is reciprocated beneath a machining head, or the machining head is reciprocated over the workpiece. Substantially always the grinding is carried out on cold workpieces and, irrespective of how the grinding operation is placed in the prod¬ uction line, it always'is a separate operation. his means that buffer stores must be provided on the inlet as well as on the outlet side of the grinding station. The grinding, thus, requires much space and relatively much time. Moreover, even when the grinding is carried out on hot workpieces between their discharge fr ^' om the continuous casting to the rolling mill, a substantial temperature loss occurs during the grinding, because the grinding inclusive of its bufferting inlet and outlet requires quite a considerable time. This, together with the handling of hot workpieces, makes protective measures necessary which are somewhat more effective than at the handling of cold workpieces.

In order to eliminate the aforesaid problem, the invent¬ ion has the object to provide a grinding method and a

OΛΪPΪ ^«

device therefor, by which continuous grinding of a workpiece is rendered possible, i.e. the grinding can be carried out on the continuous cast material after the casting but prior to the dividing into workpieces when the continuous cast strand is fed through the grinding machine. Especially by utilizing the hot grind¬ ing directly on the strand, a surface conditioning without disturbing interference in the production chain is obtained. The higher workpiece temperature at the grinding reduces the risk of crack formation, the cutting speed can be kept higher at a lower effect, the production capacity is increased, and better work- piece surfaces can be obtained. Owing to the lower effect required for the grinding, also the wear of the grinding wheels is reduced. When the grinding mach¬ ine is made an integral part in the casting process, as described above, it does not cause any energy loss¬ es from the continuous cast material. The total energy losses, thus, decrease, which implies that the sub¬ sequent heating preceding the rolling can take place more rapidly, which additionally contributes to a corr¬ ect and thereby less expensive plant.

According to the invention, the cutting members are arr¬ anged overlapping for each surface on the workpiece, so that either the entire surface of the workpiece ^' can be machined or alternatively the separate units can be controlled separately for spot machining during the continuous feed of the workpiece through the grinding station.

At a preferred embodiment of the invention, the grind¬ ing station comprises a plurality of grinding modules, each with a grinding spindle axle substantially perp¬ endicular to the respective surface of the strand, i.e. the grinding wheel almost in parallel with the surface. Due to the overlapping arrangement, the entire surface

of the strand can be ground during the passage of the workpiece through the grinding station.

In order to safely prevent overheating of the grinding wheels, the wheels preferably are cooled, either with air or water or a combination of both. At spot grinding of the surface, each grinding module preferably is con¬ trolled individually from a preceding crack or defect detection of the workpiece surface.

The invention is described in greater detail in the following by way of an embodiment thereof and with ref¬ erence to the drawings, in which Fig. 1 is a lateral view of a grinding device according to the invention, and Fig. 2 shows the same device or machine seen in the longitudinal direction of the strand.

The grinding machine shown in the drawings is located in direct connection to the straighetning rollers 8 of the continuous casting machine, between which rollers the workpiece 2 is passed through. The grinding mach¬ ine comprises a machine stand 7, in which a plurality of grinding modules 3 are located. Each grinding mod¬ ule comprises a substantially vertical spindle 3 driv¬ en by a motor 6 via an axle 5 provided with splines, and on each spindle a grinding wheel 1 is mounted. Due to the spline connection between motor and spindle 3 _. the spindle can be moved in the direction to and from the workpiece 2. This vertical movement for the grind¬ ing wheel and spindle is controlled by. a hydraulic cyl¬ inders., which is attached in a grinding stand 4 and, respectively, via a lug (bracket) is attached to the grinding spindle. Each grinding stand 4 for a grinding module is suspended adjustably in the machine stand for adjusting the angle of action of the grinding wheel relative to the workpiece. Said suspension of the grinding modules also renders it possible to relatively rapidly and simply exchange the modules

O PI r- wipo

for reparation and service.

As appears from Figs. 1 and 2, the grinding machine des¬ cribed comprises four upper and four lower grinding mod¬ ules, which are so offset in lateral direction that their grinding areas overlap each other and cover the entire width of the workpiece. The machine, of course, also can be equipped for edge grinding the workpiece, but this is not shown for reasons of clearance.

Cooling water for cooling the grinding wheels is supp¬ lied via an angle 10 to passageways in the spindle axle which are branched off to wheel flange and grind¬ ing wheel. The greater part of the cooling water con¬ sumed is vaporized upon contact with the hot workpiece. The waste water which was not vaporized is collected via protective metal sheets in a waste water container beneath the machine. The protective metal sheets also are a protection against bursting of the grinding wheels. The grinding machine preferably is provided with detection means to ensure that the machine does not operate when there is no workpiece in the machine. The waste water collection can be completed in a way not shown in detail with a pump means and sedimentat¬ ion means. The machine, of course, also is provided With evacuation units for handling grinding dust and water vapour, but these equipments are not shown, either, for reasons of clearness. In normal case the machine is provided with a device measuring the grinding motor effect and utilizing the measured value for controlling the pressure in the hydraulic cylind¬ er 9 and thereby the adaptation force to the workpiece for holding the motor effect constant. The contact of the grinding wheel with the workpiece surface prefer¬ ably is controlled by the system for effect control of the grinding wheel. Hereby a soft grinding contact

OMPI

and coupling-in to effect-controlled grinding for hold¬ ing the grinding depth constant are obtained.