Surface treatment of metal billets

Abstract: Apparatus and a method for removing surface defects from elongate metal billets (1) arranged in side-by-side relation, comprises a support framework (3,4,5,6) carrying a grinding wheel assembly (7), the support framework being adapted to move the grinding wheel (7) in three mutually orthogonal directions.

Description: The invention relates to the surface treatment of metal billets and the like and in particular the removal of surface and subsurface defects by grinding. Billets can have surface defects such as cracks or inclusions which must be removed. It is known to treat the surface defects by first inspecting the billets, marking the location of the defects and then removing the defects by grinding. The known methods of grinding either involve moving the billets one by one underneath a motorised grinding wheel at a feed location or laying a plurality of the billets in side-by-side and end-to-end relation on a work table and then grinding the defects using a low powered hand held grinding tool. The work is dirty and dangerous. Both methods are time consuming, and there is a need for a method of treating billets which is reliable, efficient and involves less danger for the operator. FR-A-2125956 teaches a method of removing a surface defect on an elongate metal billet by grinding away the defect using a grinding wheel mounted in a framework, means connected to the framework being adapted to move the grinding wheel in three mutually orthogonal directions, in which the grinding wheel is advanced to overlie the defect, the wheel is lowered and the defect ground away. The present invention provides an improved method of treating the billets. Accordingly in one aspect the invention provides a method of removing a surface defect on an elongate metal billet by grinding away the defect using a grinding wheel mounted in a support framework, means connectable to the framework being adapted to move the grinding wheel in three mutually orthogonal directions, actuating the means so as to advance the grinding wheel until it overlies the defect, lowering the wheel and grinding away the defect, characterised in that the billets are of rectangular cross section and are arranged in side-by-side relation on a table, which table includes longitudinally extending recesses transversely spaced apart across the table and shaped to hold a longitudinal corner portion of a billet, the billets are moved across the table so as to cause a longitudinal corner portion of the billet to be received in a recess, thereby rotating the billet through substantially 45° so as to present the opposing longitudinal corner portion uppermost to the grinding wheel and moving the billet across the table to progressively rotate the billet and expose successive faces uppermost. The grinding wheel and the support can be controlled from a remote location: eg from behind a screen, so the work is less hazardous for the operator. Preferably the billets are laid in both side-by-side and end-to-end relation, as a horizontal or array of billets. In such a case, the grinding wheel can be quickly moved from one billet to another and the defects are efficiently treated. In another aspect the invention provides an apparatus for use in removing surface defects from a plurality of billets. The apparatus comprises a support framework having a grinding wheel mounted thereon, the support framework including means for moving the grinding wheel in three directions arranged mutually orthogonally, actuating means so as to advance the grinding wheel until it overlies a defect and means to raise and lower the grinding wheel characterised in that the apparatus includes a table on which the billets of rectangular cross-section can be arranged in side-by-side relation, the table having longitudinally-extending recesses transversely spaced apart across the table, the recesses being of a shape to hold a longitudinal corner of a billet and means to push the billets accross the table whereby their corners are received in and rotated through 45° by successive recesses. The billets are preferably arranged relative to the apparatus so that the first carriage travels in a direction parallel to the longitudinal axis of the arranged billets. The grinding wheel is preferably suspended from the support by a lever arm pivotally mounted about a horizontal axis, whereby the wheel is adapted for movement in a vertical direction. The lever arm may also be pivotally mounted on the support about a vertical axis. Longitudinal surface defects are often present on the corner portions of the billets and it is difficult with the known methods to reliably or efficiently treat those defects. It is known to turn the billets manually using a lever both to expose the corners and to present the other faces for treatment, but this can be awkward. The invention overcomes this difficulty. In another aspect of the invention there is provided a method of treating surface defects on different surfaces of an elongate metal billet of rectangular cross section, the method comprising laying the billet on a table, to present a face for treatment of its surface defects, the table including a plurality of transversely spaced apart longitudinally extending substantially v-shaped recesses shaped to receive a longitudinal corner portion of the billet, moving the billet in steps across the table so that successive corner portions are received in successive recesses, and lowering surface treatment apparatus towards each successive side face presented for treatment of the surface defects thereby to remove the defects on successive faces. In order that the invention may be well understood, various embodiments thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic exploded perspective view of one embodiment of apparatus for use in the invention; Figure 2 is an end elevation of an embodiment of the invention; Figure 3 is a side view of the apparatus of Figure 2; Figure 4 is a fragmentary partial top plan view of the apparatus of Figures 2 and 3; Figure 1 shows schematically groups of elongate metal billets 1 which are arranged in side-by-side relation upon a table 2. Each billet typically of steel may measure between, say, 1 and 30 m long and be of square or rectangular cross section having a side dimension of between about 5 and about 13 cm. The groups are arranged in end to end relation. Apparatus for use in treating the billets comprises rails 3 extending on each side of the table 2 parallel to the longitudinal axis of the arranged billets. A first carriage 4 is mounted for movement along the rails and comprises a box-like frame made from elongate frame members joined together, e.g. welded. A second carriage 5 is mounted in the upper part of the first carriage 4 and is arranged to reciprocate along a path at right angles to that travelled by the first carriage 4. A third carriage 6 is mounted upon the second carriage 5 and is arranged to reciprocate along a shorter path generally parallel to that of the first carriage 4. A grinding wheel assembly 7 is suspended from the third carriage and is movable vertically between a raised and a lowered condition, as will all be described in greater detail. One embodiment of the apparatus is shown in greater detail in Figures 2 to 4. The first carriage 4 comprises four uprights 10 which are joined at their top by two side frame members 11 and two bridging or cross members 12. A wheel housing 13 is present at the foot of the uprights 10 at each side. Two wheels 14 are present in each housing, each pair of wheels being driven by a drive belt 15 connected to a motor 16 to cause the carriage 4 to travel along the rails 3. The second carriage 4 comprises a generally rectangular planar framework of frame members 21 joined together at the corners. The second carriage 5 reciprocates along rails 17 extending along the uppermost surface of the bridging members 12 of the first carriage 4. Wheels 22 are present below the member 21 to engage the rail 17. An electric motor 23 connected by a drive belt 24 to an axle 25 present underneath the topmost frame members 12,13 of the first carriage 4 to power movement of the second carriage. A wheel 26 having a resilient tyre, e.g. rubber is present at each end of the axle 25. A screw 27 having a handle 28 is present to urge the wheel 26 into engagement with the underside of the bridging member 12 of the first carriage 4. The third carriage 6 reciprocates along rails 29 extending along the uppermost surface of those frame members 21 of the second carriage which extend in a direction generally parallel to the side frame members 12 of the first carriage 4. The third carriage comprises a rectangular planar framework of frame members 30 joined together. Wheels (hidden from view in the drawings) are present to engage the rails 29. The drive means for the third carriage comprises a stepper motor 31 mounted on the second carriage connected by a rotary crank assembly 32, rotation of the crank by the motor causing the third carriage to reciprocate across the second carriage. The grinding wheel assembly 7 is suspended from the third carriage and comprises framework 40 hanging beneath the level of the topmost members of the first carriage. A grinding wheel 41 is mounted at one end of a balanced lever arm 42 which is pivotally mounted about a horizontal axis. A motor 43 and drive belt 44 are present on the arm 42 to rotate the grinding wheel 41. The motor is preferably of low to medium power, e.g. about 5.5 kw. An electric motor 45 is mounted on the top of the carriage 6 and is connected by a drive belt 46 via an electromechanical clutch assembly 47 to a pinion 48. The pinion 48 engages an elongate rack 49 which is inclined upwardly at a shallow angle. A pivotally mounted rod 50 extends between the elevated end of the rack and the lever arm 42, whereby the motor 45 provides the power for pivotal movement of the arm 42. A platform 18 extends to one side of one of the bottom side frame members upon which, as shown, an operator is sitting and controlling the grinding wheel assembly 7 from a control box 19. A protective screen is preferably present through which he can monitor the process. In use, the billets are firstly inspected for defects and marked, e.g. with a stripe of paint. They may be inspected visually or e.g. using x-rays. The billets are arranged on the table 2 and the first carriage 4 is advanced until the wheel 41 is generally above but spaced across the table 2 from the start of the first defect to be treated. The second carriage 5 is then moved across the table until the wheel symmetrically overlies the leading edge of the defect. The motor 45 is then actuated to lower the wheel 41 onto the surface of the billet 1. This action transfers power through the clutch 47 to the pinion 48 which moves the rack 49 in a downward direction, thereby lowering the wheel 41, which travels through an arcuate path. The pressure applied by the wheel 41 onto the surface of the billet can be adjusted by control or "slipping" of the clutch 47. The wheel is rotated by switching on the motor 43. Short longitudinally extending defects can be ground away by moving the third carriage along its rails 29. Because the third carriage 6 is so much smaller than the first carriage 4, it is much more accurately controlled. The resilient tyres 26 and the clamping mechanism 27 between the second and first carriages reduce any problems caused by vibration and ensure the defect is accurately ground away. The billets can be turned, both to treat defects on side surfaces which are hidden, and to treat defects on the corners of the billets. The table 2 includes a plurality of transversely spaced apart v-shaped recesses 60 in the uppermost surface. The recesses are shaped to hold two adjacent side faces of a billet, so that the opposing longitudinal corner portion faces uppermost. A vertical wall 61 is present at one side of the table 2. In use, by pushing the billets from one side across the table, each billet can be progressively rotated to expose successive side faces so that defects thereon can be treated. Surface defects which are present on the longitudinal corner portions can also be treated when the billet is supported in a recess 60. Four recesses 60 are shown but the number is not critical.

Claims: A method of removing a surface defect on an elongate metal billet (1) by grinding away the defect using a grinding wheel (41) mounted in a support framework (3,4,5,6), means (16,23,31,45) connectable to the framework being adapted to move the grinding wheel (41) in three mutually orthogonal directions, actuating the means (16,23,31,45) so as to advance the grinding wheel (41) until it overlies the defect, lowering the wheel (41) and grinding away the defect characterised in that billets (1) of rectangular cross section are arranged in side-by-side relation on a table (2), which table includes longitudinally extending recesses (60) transversely spaced apart across the table (2) and shaped to hold a longitudinal corner portion of a billet, the billets (1) are moved across the table (2) so as to cause a longitudinal corner portion of a billet to be received in a recess (60), thereby rotating a billet through substantially 45° so as to present the opposing longitudinal corner portion upper most to the grinding wheel (41) and moving the billet (1) across the table to progressively rotate the billet and expose successive faces uppermost. A method according to Claim 1 characterised by advancing a first carriage (4) of the support framework in a direction generally parallel to the longitudinal axis of the arranged billets until the grinding wheel (41) is spaced to one side of the defect, a second carriage (5) carrying the grinding wheel (41) being mounted upon the first carriage (4), and advancing the second carriage (5) sideways across the billets (1) until the grinding wheel overlies the defect. A method according to Claim 1 or 2 characterised in that the billets (1) are arranged in a horizontal array on a table (2). Apparatus for removing surface defects from a plurality of metal billets (1), the apparatus comprising a support framework (3,4,5,6) having a grinding wheel (41) mounted thereon, the support framework including means (16,23,31,45) for moving the grinding wheel in three directions arranged mutually orthogonally, actuating means (16,23,41,45) so as to advance the grinding wheel (41) until it overlies a defect and means to raise and lower the grinding wheel (41) characterised in that the apparatus includes a table (2) on which the billets (1) of rectangular cross-section can be arranged in side-by-side relation, the table having longitudinally-extending recesses (60) transversely spaced apart across the table (2), the recesses (60) being of a shape to hold a longitudinal corner of a billet (1) and means to push the billets (1) across the table whereby their corners are received in and rotated through 45° by successive recesses. Apparatus according to Claim 4, characterised in that the support framework comprises a first carriage (4) movable in a first direction relative to the arranged billets, a second carriage (5) mounted upon the first carriage (4) and movable in a direction at right angles to the first direction, and a third carriage (6) mounted upon the second carriage (5) and movable in a direction generally parallel to that of the first carriage (4), but to a more limited length of travel, the grinding wheel (41) being suspended from the third carriage (6); means (16,23,31) being present to move the respective carriages Apparatus according to Claim 5 characterised in that the first carriage (4) is arranged for travel on rails (3) spaced apart on either side of an elongate table (2). Apparatus according to Claim 5 or 6 characterised in that means (26,27,28) connecting the second carriage (5) to the first carriage (4) are present to suppress vibration. Apparatus according to Claim 7 characterised in that the first carriage comprises two uppermost spaced apart side frame members (11) joined by two bridging members (12) and the second carriage (5) is arranged to be driven along the upper most surface of the bridging members (12), the means to move the second carriage comprising at least one driven wheel (26) engageable with the underside of each bridging member (12), means (27,28) being present to urge the wheel into engagement with the bridging member, the wheel (26) having a tyre formed from a resilient material to suppress vibration. Apparatus according to any of Claims 5 to 8 characterised in that the grinding wheel (41) is disposed on a lever arm (42) movable between a lowered condition and a raised condition. Apparatus according to Claim 9 characterised in that a motor (45) mounted upon the third carriage (6) is present to raise and lower the lever arm (42) and thereby the grinding wheel (41), and adjustable clutch means (47) are present between the motor (45) and the arm (42), whereby the pressure applied by the grinding wheel (41) upon the surface of the billet (1) may be adjusted by control of the clutch means. Apparatus according to any of Claims 5 to 10, characterised by means (129) arranged to pivot the grinding wheel about a vertical axis. A method of treating surface defects on different surfaces of an elongate metal billet of rectangular cross section, the method comprising laying the billet (1) on a table (2), the table (2) to present a face for treatment of its surface defects and lowering surface treatment apparatus (41) towards the face, characterised in that the table (2) includes a plurality of transversely spaced apart longitudinally extending substantially v-shaped recesses (60) shaped to receive a longitudinal corner portion of the billet, moving the billet in steps across the table so that successive corner portions are received in successive recesses, whereby each successive side face may be presented for treatment of the surface defects thereby to remove the defects on successive faces.

Inventors: DETRONDE MICHEL, MARCUZZI ADOLFO, DETRONDE, MICHEL, MARCUZZI, ADOLFO
Applicants: SOMAFER SA, SOMAFER S.A.
Application year: 1990
Main classification: B24B27
IPC codes: B23Q1, B24B27, B23Q7