GB2110577A - Grinding machine for treating the generated surface of a roll - Google Patents

Abstract

The grinding machine comprises a grinding wheel (11) and at least one hydrostatic support element (18, 18a) having a ram (piston 21) guidable towards the side of the roll remote from the grinding wheel (11), the ram having a concave bearing surface (23) engageable with the generated surface of the roll. The bearing surface (23) comprises at least one hydrostatic bearing pocket (23') communicating via a restrictor bore (25) with the pressure chamber (cylinder chamber 26) associated with the ram (piston 21), the pressure chamber being connected to a hydraulic fluid feed line (27). The ram (piston 21) supplied with the hydraulic fluid is pressed on to the roll (4), some of the pressure fluid flowing through the restrictor bore (25) into the bearing pocket (23') and forming a film of pressure fluid between the bearing surface (23) and the generated surface of the roll. The roll (4) is therefore supported reliably and without contact in the operative region, so that vibrations of the roll (4) can be obviated, but without impairment of the texture of the generated surface. <IMAGE>

Description

SPECIFICATION Grinding machine for treating the generated surface of a roll This invention relates to a grinding machine for treating the generated surface of a roll and having guides for the two ends of the roll and, movable towards the generated surface, a grinding wheel which is rotatable around an axis extending substantially parallel to the roll longitudinal axis and is coupled with drive means, the guides and the grinding wheel being disposed on two support members, at least one of which is movable relatively to the other in a direction parallel to the roll longitudinal axis.

Known machines of this kind are prone to cause disturbing vibrations of the workpiece, more particularly when the workpieces are relatively long thin rolls; the vibrations may impair grinding considerably and make low-cost and rapid machining of the roll difficult. Often, it is impossible to provide local mechanical support for the roll, for instance by means of a rest subdividing the roll length, more particularly when the workpieces are rolls whose surface texture and dimensional accuracy must be to very high standards, as in the case, for instance, with the initial grinding and the regrinding of calender rolls, such as those used in the preparation of metal foils. Rolls of this kind are usually required to have a uniformly smooth generated surface which must, therefore, be ground without other contact.

It is an object of the invention so to improve a grinding machine of the kind specified that the roll to be treated is retained in the treatment zone in a treatment position exactly defined relatively to the grinding wheel substantially free from vibrations and without impairment of its surface texture.

According to the present invention, therefore, a grinding machine for treating the generated surface of a roll has: guides for the two ends of the roll: a grinding wheel which is movable towards the generated surface of the roll, is rotatable around an axis extending substantially parallel to the longitudinal axis of the roll, and is coupled with drive means; the guides and the grinding wheel being disposed on two support members at least one of which is movable relatively to the other in a direction parallel to the roll longitudinal axis; and at least one hydrostatic piston-and-cylinder support element disposed substantially opposite the grinding wheel and guidable towards the side of the roll remote from the grinding wheel, the support element having a first part which is stationary relatively to the grinding wheel and a second part which is movable transversely of the roll generated surface, the second part having a concave bearing surface engageable on the roll generated surface, the bearing surface having at least one hydrostatic bearing pocket communicating, by way of a restrictor bore extending through the movable part; and a feed line to connect the stationary part with a supply of hydraulic pressure fluid.

Similar hydrostatic support systems are known per se in a different context, for instance, from United States patent specification 3 802 044, for compensating for the sag of a hollow cylindrical roll shell rotatable around a stationary support.

In the hydrostatic support element according to the invention, the pressure fluid flowing through the bearing pocket and issuing therefrom by way of its side edges builds up between the bearing surface of the support element and the generated surface of the roll a permanently operative hydraulic film, so that the roll to be treated is guided reliably and without direct contact in the operative zone. The invention also makes possible the observation and constancy of a predetermined and, advantageously, readily controllable support force which is so applied to the workpiece during grinding as to oppose the pressure applied by the grinding wheel.

In a very expedient and constructionally simple embodiment of the invention, of use, for instance, in the conversion of existing grinding machines, the stationary part of the support element can be disposed on a mounting connected to the grinding wheel support member.

Conveniently, the support element is offset from the grinding wheel in the direction of the roll longitudinal axis. This feature - assuming that the support element is disposed before the grinding wheel in relation to the axially parallel relative movement thereof - obviates the risk of impairment of the surface texture of the treated part of the roll. Correspondingly, any damage which the generated surface has suffered near the support element during the grinding step can be detected and made good.

Conveniently, as a means of providing very effective vibration damping of the support element, the surface of the hydrostatic bearing pocket or bearing pockets which approaches the roll is less than 60% of the total concave bearing surface of the support element. Consequently, the support element has relatively wide marginal webs bounding the or each bearing pocket, so that the relatively large proportion of the hydraulic film which is disposed above the margins is operative for vibration damping.

Preferably, the hydraulically effective area of the movable part of the support element is between 20 and 40% of the area of the concave bearing surface. A ratio of this kind between the operative surfaces of the support element calls for or makes possible - for a given pressure of the support element - the use of a relatively high working pressure for the hydraulic fluid, such pressure being correspondingly easier to control than a lower pressure.

According to a constructionally very simple feature of the invention providing very accurate roll guidance at an advantageously reduced constructional outlay, in a support element having a single hydrostatic bearing pocket the cylinder may have a bore which extends fairly tightly around substantially the whole length of the piston part received therein, the diameter of the bore being greater than the diameter of the piston by a clearance permitting substantially only relative axial movements.

On the other hand, in a support element having a plurality of bearing pockets, more particularly four, the cylinder can have a bore which extends around the piston with a relatively large clearance permitting adjusting movements of the movable part transversely of its longitudinal axis, there being a ring seal which extends tightly around the piston. This enables the support element to be adjusted according to the pattern of the generated surface to be supported, so that the roll to be machined can be guided reliably despite relatively large differences between the patterns of those parts of the generated surface which are near the support element and the grinding wheel, for instance, in the case of rolls having a longitudinally convex generated surface.

To achieve very reliable guidance substantially without vibration in the operative zone of the roll to be treated, if two support elements are provided, they are offset from one another by an angle of between 90 and 1 500 about the roll longitudinal axis.

As a very simple way of providing a considerable improvement of vibration damping, a restrictor may be disposed in the hydraulic feed line. In this case the hydraulic fluid can have a relatively high and, therefore, relatively easily controllable pressure upstream of the restrictor and it is a simple matter to reduce the pressure by corresponding restriction to a value necessary for vibration damping.

The hydraulic feed line can comprise a pressure regulator controllable, by way of a signal derived from the control of the drive means, in dependence upon the power input thereto. This provides a very simple way of adapting the pressure of the support elements to the cutting force of the grinding wheel as determined by adjustment of the longitudinal and circular feed of the grinding machine.

It is very economical for the hydraulic fluid to be a lubricant which is also directed between the grinding wheel and the generated surface of the roll. The use of the lubricant which is usually present in sufficient quantity in grinding machines enables the advantages of the invention to be achieved without additional expenditure on the storage of operating agents and also helps to improve lubrication in the grinding zone by virtue of the film of hydraulic fluid applied by way of the support element very close to the grinding zone.

The invention may be carried into practice in various ways but one grinding machine embodying the invention and a number of modifications will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a partial plan view partly in section of a grinding machine having support elements arranged according to the invention; Figure 2 shows the machine of Figure 1 in a cross-section on the line Il-Il of Figure 1; Figure 3 is a view to an enlarged scale of a detail of the machine of Figure 1; Figure 4 shows a detail of a modification of the machine, the view being in a partial section similar to the view of Figure 2; Figure 5 is a partial plan view with a partial section of another modified grinding machine; and Figures 6 and 7 each show a different modification of the arrangement according to the invention of support elements, in each case in a diagrammatic partial view simiiar to Figure 2.

The machine shown in Figures 1 and 2 comprises a machine bed 1; secured thereto are two bearings 2, 3 in which the ends of a roll 4 to be machined are mounted for rotation; at least one of the two roll ends and in the case of very thin rolls each roll end has drive means associated with the respective bearing 2 or 3. The drive means are not shown. The bed 1 has a dovetail guide 6which extends horizontally and parallel to the longitudinal axis of the roll 4 and on which a carriage 6 is guided for movement in the longitudinal direction, as indicated by arrows 9.

The carriage 6 has a dovetail guide 7 which extends horizontally and transversely of the guide 5 and on which a support plate 8 carrying a grinder 10 is movable transversely as indicated by arrows 9b.

The grinder 10 comprises a grinding wheel 11 which can be guided towards the generated surface of the roll 4 and is disposed on a shaft 12 mounted for rotation about an axis parallel to the longitudinal axis of the roll 4, the grinder 10 also comprising an electric driving motor 13 which is secured to the plate 8 and connected via a vee belt drive 14 to the shaft 12. The shaft 12 is mounted in a bearing 15 secured to a retaining member 16 on the plate 8. A support 1 7 which extends above the roll 4 is secured to the retaining member 16 and carries at its free end a hydrostatic piston-and-cylinder support element 18 disposed opposite the grinding wheel 11.The support element 18 comprises a cylinder 20 secured to the support 17 and a piston 21 guidable towards that part of the generated surface of the roll which is remote from the grinding wheel 11, the piston 21 being guided sealingly, in a ring seal 22 disposed in the cylinder 20, for movement transversely of the roll 4 as indicated by the arrows 9b. A second support element 1 8a disposed at an offset of approximately 900 from the first support element 18 is secured by way of a bracket 19 to the plate 8. The piston 21 of the support element 1 8a is guidable towards the underside of the roll 4 and is guided for substantially vertical movement in the associated cylinder 20. Each cylinder 20 has a bore which surrounds the piston 21 with a relatively large clearance permitting adjusting movements of the particular piston 21 concerned relatively to its longitudinal axis.

The support elements 18, 1 8a are so disposed that their longitudinal axes in a transverse plane extending through the grinding wheel 11, the longitudinal axis of the support element 1 8 being disposed, together with the longitudinal axes of the roll 4 and shaft 12, in a common plane E which in the example shown is substantially horizontal.

Figure 3 is a plan view of one of the pistons 21 in the direction of its longitudinal axis. As can be gathered more particularly from Figure 2, the pistons 21 each have a concave bearing surface 23 which is engageable with the generated surface of the roll, is formed on an enlarged head part 24 on the cylindrical piston part and is rectangular as seen in Figure 3. Diameter D of the piston part is such that the piston surface or area is from 20 to 40% of the bearing surface 23 determined by dimensions A and B, the larger dimension A extending lengthwise of the roll 4 and the smaller dimension B extending round the roll periphery.

The bearing surface 23 has four hydrostatic bearing pockets 23' each communicating by way of a restrictor bore 25 with a cylinder chamber 26 bounded by the piston 21 and the end of the cylinder 20. The cylinder chambers 26 of the two cylinders 20 are connected to a hydraulic feed or supply line 27 communicating with a hydraulic reservoir 28. The reservoir 28 can hold, for instance, a lubricant which can be guided towards the grinding wheel 11 and the generated surface of the roll during grinding and which can therefore also serve as a pressure fluid.

The feed line 27 comprises a circulating pump 30, a pressure-regulating valve 31 downstream of the pump and a manually adjustable restrictor 32 disposed between the valve 31 and the cylinders 20. The valve 31 can be actuated by way of an element 33 controllable by way of control lines 34, 35. The line 34 is connected to a pressure detector 36 disposed between the restrictor 32 and the cylinders 20 and serves to transmit a setvalue signal derived from the detector 36. The control line 35 is connected to a measuring element 37 associated with the motor 13 and is adapted to transmit a control signal derived from the element 37. Referring to Figure 1, the element 37 can be an ammeter connected to the current supply line 39 of the motor 13, the valve 31 being controlled in dependence upon the power consumption or power input of the motor 13.Line 37 is connected between the pump 30 and the valve 31 to a return line 38 which extends to the reservoir 28 and which comprises a relief valve 40 adjustable to a predetermined pressure.

In operation, the roll 4 to be ground and the grinding wheel 11 are rotated, preferably in the same direction, by way of a roll drive facility (not shown) and by way of the motor 13, respectively.

The carriage 6 can be coupled with drive means (not shown) adapted to move the carriage 6 at choice in either longitudinal direction along the roll 4, so that the grinder 10 disposed on the carriage 6, together with the support elements 1 8, 1 8a, make a longitudinal advance or feeding movement. To adjust the circular feed of the grinder 10, the transversely movable plate 8 can be coupled with a manual adjusting device (not shown).

The support elements 1 8, 1 8a apply to the roll 4 two bearing forces which form a resultant bearing force substantially opposing the pressure of the grinding wheel 11 and which prevent deflection of the roll 4 in the grinding zone and inhibit vibrations of the roll 4. The pressure fluid supplied to the support elements 1 8, 1 8a acts to produce the bearing force to be applied via the piston 21 to the roll 4 and to maintain between the bearing surface 23 and the generated surface of the roll a permanent film of hydraulic fluid which prevents direct metal-to-metal contact between the surface 23 and the roll 4.The pressure fluid film is formed because the pressure fluid issues from the cylinder chamber 26 through the restrictors 25, with a loss of pressure, to the bearing pockets 23' and discharges outwardly by way of the marginal parts of the bearing surface 23 which extend right around the bearing surface 23, a gap through which the pressure fluid flows always being present between the generated surface of the roll and each of the bearing surfaces 23. Vibration damping of the roll 4 is provided more particularly by those zones of the film which are disposed above the marginal parts of the bearing surface 23. Conveniently, therefore, the marginal parts are relatively wide - i.e., the total area of those surfaces of the pockets 23' which approach the roll 4 is less than approximately 60% of the total bearing surface 23.

Since the area of the piston 21 is smaller than the bearing surface 23, the necessary bearing force needs to be produced by a pressure fluid at a working pressure which is relatively high and, therefore, controllable very economically. The working pressure is so controlled by way of the valve 31 in dependence upon the power consumption of the motor 1 3 as determined by the longitudinal feed and circular feed of the grinder 10 that an increased power consumption of the motor 1 3 leads to a corresponding increase of the working pressure and, therefore, of the bearing forces which the elements 1 8, 1 8a apply to the roll 4. Surplus pressure fluid delivered by the circulating pump 30 returns to the reservoir 28 via the return line 38.The pressure fluid supply and the adjustment of the pressure can be set at a relatively high and, therefore, correspondingly readily controllable pressure which is reduced by the restrictor 33 to the extent necessary for actuation of the pistons 21. Correspondingly, the conveying and control facilities for the pressure fluid can be of relatively simple and rugged construction virtually irrespective of the pressures required in the cylinder chambers 26.

As can be gathered from Figure 4, a piston-andcylinder support unit 43 guidable towards the generated surface of the roll can have a stationary piston 45 secured to the support 17 and a cylinder 44 which is sealingly and movingly guided on the piston 45 in the direction of the longitudinal axis thereof, the bearing surface 23 which is engageable with the roll 4 and the restrictor bores 45 being present at the head end of the cylinder 44.

In the constructions shown in Figures 1 to 4, the moving members of the support elements 1 8, 1 8a, 43 are in each case guided for movement either transversely of the longitudinal axis of the corresponding stationary member or at an inclination to such axis. Consequently, the pistons 21 and the cylinder 44 can be adjusted to suit rolls having non-cylindrical generated surfaces, for instance, generated surfaces which are convex over some or all of their length, in accordance with the pattern of that part of the generated surface which is in the treatment zone. but without impairment of roll guidance.

Referring to Figure 5, like elements have the same references as in Figure 1. The machine of Figure 5 has a single piston-and-cylinder support element 48 which is guidable towards the side of the roll remote from the grinding wheel 11 and which is offset therefrom along the length of the roll 4. The support element 48 comprises a cylinder 50 secured to the support 17 and a piston 51 which moves in the cylinder 50 perpendicularly to the roll longitudinal axis and whose head part 24 is formed with a concave bearing surface 53 engageable with the generated surface of the roll.

The surface 53 has a single hydrostatic bearing pocket 53' which is bounded by four marginal parts and which communicates by way of an axial restrictor bore 25 with cylinder chamber 26. In this construction the cylinder 50 has a bore whose diameter is greater than the diameter of the piston 51 only by a reduced amount permitting merely relative axial movements of the piston 51.

Correspondingly, firm parallel guiding of the piston 51 is provided; if required, the support surface 53 need not be subdivided. This construction is of use only for the treatment of cylindrical rolls.

Arranging the grinding wheel 11 at a lengthwise offset from the support element 48 is convenient more particularly when the support element 48 is disposed before the grinding wheel 11 as considered in the direction (arrow 9a) of movement of the grinder 10, for instance, during the final grinding pass, so that any damage which the generated surface has suffered in the region of the bearing surface 53 can be cleared in the next pass of the grinding wheel 11. Of course, two support elements 48 can be used.

As can be gathered from Figure 6, when two support elements are used, they can be arranged with pistons 21 inclined at any desired adjustable angle a or a1 to the horizontal plane E; the angles a and a, can be adjusted in accordance with the predetermined position of the required resulting bearing force. The sum of the angles a and 1 can be between 900 and 1500.

When two support elements are used, they can be designed, for instance, by having different piston areas, to transmit different bearing force components which together determine the position of the resultant bearing force.

Referring to Figure 7, when a single support element is used it can be disposed at an inclination to the horizontal plane E; the angle a of inclination of the piston 21 can be such that its bearing force substantially opposes the cutting force of the grinding wheel 11 resulting from the horizontal pressure thereof and the vertical component of the grinding force.

Another possibility is for the roll to be ground to be arranged with its longitudinal axis vertical and for the grinder to be guided correspondingly in the vertical direction. Also, the grinder and its associated hydrostatic support elements can be stationary while the roll to be ground and its guide members can be arranged for movement in the direction of the roll longitudinal axis.

Claims (13)

1. A grinding machine for treating the generated surface of a roll and having: guides for the two ends of the roll; a grinding wheel which is movable towards the generated surface of the roll, is rotatable around an axis extending substantially parallel to the longitudinal axis of the roll, and is coupled with drive means; the guides and the grinding wheel being disposed on two support members at least one of which is movable relatively to the other in a direction parallel to the roll longitudinal axis; and at least one hydrostatic piston-and-cylinder support element disposed substantially opposite the grinding wheel and guidable towards the side of the roll remote from the grinding wheel, the support element having a first part which is stationary relatively to the grinding wheel and a second part which is movable transversely of the roll generated surface, the second part having a concave bearing surface engageable on the roll generated surface, the bearing surface having at least one hydrostatic bearing pocket communicating, by way of a restrictor bore extending through the movable part; and a feed line to connect the stationary part with a supply of hydraulic pressure fluid.

2. A machine as claimed in Claim 1 in which the stationary part of the support element is disposed on a mounting connected to the support member of the grinding wheel.

3. A machine as claimed in Claim 1 or Claim 2 in which the support element is offset from the grinding wheel in the direction of the roll longitudinal axis.

4. A machine as claimed in Claim 1 or Claim 2 or Claim 3 in which the surface of the hydrostatic bearing pocket or bearing pockets which approaches the roll is less than 60% of the total concave bearing surface of the support element.

5. A machine as claimed in any of the preceding claims in which the hydraulically effective area of the movable part of the support element is between 20 and 40% of the area of the concave bearing surface.

6. A machine as claimed in any of the preceding claims in which the support element has a single hydrostatic bearing pocket, the cylinder has a bore which extends fairly tightly around substantially the whole length of the piston part received therein, the diameter of the bore being greater than the diameter of the piston by a clearance permitting substantially only relative axial movements.

7. A machine as claimed in any of Claims 1 to 5 in which the support element has a plurality of bearing pockets, the cylinder has a bore which extends around the piston with a relatively large clearance permitting adjusting movements of the movable part transversely of its longitudinal axis, there being a ring seal in the bore which extends tightly around the piston.

8. A machine as claimed in any of the preceding claims which includes two support elements offset from one another by an angle of between 90 and 1 500 about the roll longitudinal axis.

9. A machine as claimed in any of the preceding claims which includes a restrictor in the hydraulic feed line.

10. A machine as claimed in any of the preceding claims in which the hydraulic feed line comprises a pressure regulator controllable, by way of a signal derived from the control of the drive means, in dependence upon the power input thereto.

11. A machine as claimed in any of the preceding claims which includes a hydraulic fluid is a lubricant which is also directed between the grinding wheel and the generated surface of the roll.

12. A grinding machine substantially as described herein with reference to Figures 1 to 3 of the accompanying drawings.

13. A machine as claimed in Claim 12 modified substantially as described herein with reference to any one of Figures 4 to 7 of the accompanying drawings.