Method of an apparatus for semi-hot forming of metallic workpieces in a rolling operation

Claim 2

Method for the semi-hot forming of metallic workpieces by a rolling process, involving electrically heating the workpieces by a heating current to a preheat temperature and then subjecting the workpieces to a non-cutting shaping by a rolling pressure exerted between a pair of tool rollers, the improvement comprising the steps of preheating the workpieces to the desired temperature by transmitting the heating current to the workpieces through the tool rollers, while rotating the workpieces between the tool rollers, and, immediately following the preheating step, continuing the rotating of the workpieces between the tool rollers and roll-forming the workpieces.

Claim 3

Method, as set forth in claim 1, comprising the step of varying the contact pressure applied by the tool rollers to the workpiece between a first contact pressure and a higher contact pressure, utilizing the first contact pressure while preheating the workpieces and applying the higher contact pressure while roll forming the workpieces.

Claim 4

Method, as set forth in claim 1, comprising the step of contacting the tool rollers to the workpieces before applying heating current and cutting off the heating current before removing the tool rollers from contact after the completion of the roll forming operation to avoid any arcing when contact between the tool rollers and workpieces is made and broken.

Claim 5

Method, as set forth in claim 1, comprising the step of cutting off the supply of heating current before commencing the roll forming step.

Claim 6

Method, as set forth in claim 1, comprising decreasing the supply of heating current before commencing the roll forming operation.

Claim 7

Method, as set forth in claim 1, comprising the step of maintaining the level of the preheat temperature substantially constant during the roll forming operation.

Claim 8

Method, as set forth in claim 1, comprising the steps of establishing a preselected preheat temperature, and measuring the temperature of the workpieces during preheating for maintaining the temperature at the desired preselecTed level.

Claim 9

Method, as set forth in claim 1, comprising the step of rotating the tool rollers through several revolutions while preheating the workpieces.

Claim 10

Method, as set forth in claim 1, comprising the step of completing the preheating of the workpieces within a preset time period as the workpieces are rotated by the tool rollers.

Claim 11

Method, as set forth in claim 1, comprising the step of completing the preheating and roll forming steps during one complete revolution of the tool rollers.

Claim 12

Method for the semi-hot forming of metallic workpieces by a rolling process involving electrically heating the workpieces by a heating current to a preheat temperature and then subjecting the workpieces to a non-cutting shaping by a rolling pressure exerted between a pair of tool rollers, wherein the improvement comprises the steps of preheating the workpieces to the desired temperature while rotating the workpieces between the tool rollers, immediately following the preheating step, continuing the rotating of the workpieces between the tool rollers and roll forming the workpieces, completing the preheating and roll-forming steps to be in one complete revolution of the tool rollers, forming a smooth surfaced circumferentially extending segmental portion on the circumferential periphery of the tool rollers and forming a profiled surface circumferentially extending segmental portion on the remaining circumferential periphery of the tool rollers, supporting the workpiece in contact with the surfaces of the tool rollers, preheating the workpiece while it is rotated in contact with the smooth surfaced portion of the tool rollers, and completing the forming operation during the remainder of one revolution while the workpiece is in contact with the profiled surface of the tool rollers.

Claim 13

Method for the semi-hot forming of metallic workpieces by a rolling process involving electrically heating the workpieces by a heating current to a preheat temperature and then subjecting the workpieces to a non-cutting shaping by a rolling pressure exerted between a pair of tool rollers, wherein the improvement comprises the steps of preheating the workpieces to the desired temperature while rotating the workpieces between the tool rollers, immediately following the preheating step, continuing the rotating of the workpieces between the tool rollers and roll forming the workpieces, completing the preheating and roll-forming steps to be in one complete revolution of the tool rollers, forming a smooth surfaced circumferentially extending segmental portion on the circumferential periphery of the tool rollers and forming a profiled surface circumferentially extending segmental portion on the remaining circumferential periphery of the tool rollers, supporting the workpiece in contact with the surfaces of the tool rollers, preheating the workpiece while it is rotated in contact with the smooth surfaced portion of the tool rollers, and completing the forming operation during the remainder of one revolution while the workpiece is in contact with the profiled surface of the tool rollers.

Claim 14

Method, as set forth in claim 1, comprising the step of varying the rotational speed of the tool rollers during the preheating step as compared to the rotational speed of the tool rollers during the roll forming step.

Claim 15

Method, as set forth in claim 12, comprising the steps of rotating the tool rollers and thereby rotating the workpiece at a first rate of speed during the preheating step, and increasing the rate of speed of rotation of the tool rollers to a higher second speed during the roll forming step.

Claim 16

Method, as set forth in claim 13, comprising the step of varying the rotational speed of the tool rollers during one complete revolution thereof from the first speed where the preheating of the workpiece takes place during a portion of one complete revolution and the second speed where the roll forming of the workpiece is completed during the remainder of one complete revolution in which the preheating has been accomplished.

Claim 17

Rolling machine for carrying out semi-hot forming of metallic workpieces comprising a pair of tool rollers having their axes disposed in parallel relationship so that the circumferential surfaces of said rollers are spaced apart for receiving a workpiece therebetween in parallel relationship with the axes of said rollers and in contact with the circumferential surfaces of said rollers, said rollers arranged to rotate in the same direction and at least one of said rollers being laterally displaceable relative to the other said roller, a support member for said rollers, means for supporting the workpiece in position between said rollers mounted on said support member, a low-voltage electrical heating unit connected to said rollers, means for electrically insulating said rollers from one another, and means in communication with said heating unit for regulating the supply of heating current to said rollers.

Claim 18

Rolling machine for carrying out semi-hot forming of metallic workpieces comprising a pair of tool rollers having their axes disposed in parallel relationship so that the circumferential surfaces of said rollers are spaced apart for receiving a workpiece therebetween in parallel relationship with the axes of said rollers and in contact with the circumferential surfaces of said rollers, said rollers arranged to rotate in the same direction and at least one of said rollers being laterally displaceable relative to the other said roller, a support member for said rollers, means for supporting the workpiece in position between said rollers mounted on said support member, a low-voltage electrical heating unit connected to said rollers, means for electrically insulating said rollers from one another, and means in communication with said heating unit for regulating the supply of heating current to said rollers.

Claim 19

Rolling machine, as set forth in claim 15, wherein said means for electrically insulating said rollers from one another comprises an insulating plate mounted on said support member, said pair of tool rollers comprising a stationary tool roller mounted on said insulating plate and insulated from said support member by said plate and a movablE tool roller directly mounted on said support member, said means for supporting the workpiece comprising a workpiece holder mounted on said insulating plate and insulated from said support member, said heating unit comprising a first cable connection connected to said stationary tool roller and a second cable connection connected to said support member whereby heating current is supplied to said rollers while said rollers are insulated from one another.

Claim 20

Rolling machine, as set forth in claim 15, wherein means are arranged for effecting a variable supply of pressure to said movable roller for varying the contact pressure exerted by said pair of rollers on the workpiece, a pressure switch operatively connected to said means for supplying variable pressure to said movable roller, said pressure switch being electrically connected to said heating unit, whereby a lower hydraulic pressure is supplied to said movable roller for heating the workpiece compared to the pressure supplied to said movable roller for forming the workpiece and said pressure switch is arranged to cut in the heating current with a delay after said movable roller contacts the workpiece and effects the lower contact pressure on the workpiece in combination with said stationary roller.

Claim 21

Rolling machine, as set forth in claim 15, wherein a temperature measuring device is positioned adjacent the location of the workpiece between said rollers in the heat radiation range of the workpiece, and a circuit breaker connected in series electrically with said temperature measuring device whereby the supply of heating current to said rollers can be terminated.

Claim 22

Rolling machine, as set forth in claim 15, wherein each said roller of said pair of rollers comprises a first circumferentially extending portion covering an equal angular part of each said roller, and a second circumferentially extending portion covering the remainder of the circumferential periphery of each said roller, said first circumferentially extending portion having a smooth concentrically arranged surface, and said second circumferentially extending portion having a profiled surface and the radius of said first circumferentially extending portion corresponding to the radius of the roller from which the profiled second circumferentially extending portion is formed.

Claim 23

Rolling machine, as set forth in claim 19, wherein each of said rollers has a circumferentially extending recess formed therein which is equal to the angular extent of said first circumferentially extending portion, said first circumferentially extending portion comprising a separate contact member positioned within said recess, and means for securing said separate first circumferentially extending portion within said recess.

Claim 24

Rolling machine, as set forth in claim 19, wherein a plurality of support rings is mounted on said rollers and spaced axially from the location of contact between said rollers and the workpiece, a trip cam mounted on each of said support rings and spaced angularly apart on the periphery of said rings, and a limit switch for each said trip cam positioned in the path of said trip cam as it rotates with said roller for supplying and interrupting the flow of heating current to said rollers.

Claim 25

Rolling machine, as set forth in claim 15, wherein means are arranged for varying the rotational speed of said tool rollers so that said tool rollers can rotate at the same speeds and the rotational speed can be varied between at least two different speeds while said rollers are positioned in contact with the workpiece.

Claim 26

Rolling machine, as set forth in claim 22, wherein each of said pair of rollers is profiled over its entire circumferential periphery, means for regulating the speeds of said rollers, and means for rotating said rollers at a first speed while said heating unit heats the workpiece and for switching to a second increased speed while said rollers form the heated workpiece.

Claim 27

Rolling machine, as set forth in claim 22, whereIn said means for regulating the supply of heat current to said rollers comprises a plurality of trip cams associated with one of said rollers, and a limit switch positioned in the path of each said trip cam for supplying and interrupting the flow of heating current to said rollers, and said limit switches are arranged operatively connected to said means for varying the rotational speed of said tool rollers so that said trip cams can also effect the change in the rotational speed of said rollers as said rollers rotate.

Claim 28

Rolling machine, as set forth in claim 22, wherein the circumferential peripheral surface of each of said rollers is composed of two portions, one of said portions is smooth and the other said portion is profiled, trip cams associated with one of said rollers and a limit switch arranged in the path of each of said trip cams so that as said roller with said trip cams is rotated said limit switches effect the change in rotational speed of said tool rollers.

Claim 29

Rolling machine, as set forth in claim 25, wherein at least one additional trip cam is provided on said roller and a limit switch is arranged in the path of said additional trip cam, said additional trip cam being arranged to contact its associated said limit switch as the smooth surface portion of said rollers is in contact with the workpiece for effecting an increase in speed in said rollers during the period of contact between the workpiece and the smooth surface portion of said rollers.

Claim 30

Rolling machine, as set forth in claim 22, wherein a thyristor-controlled electromotor is arranged for driving said tool rollers.