Gantry-type machine tool

Abstract: A machine tool provides at least one set of cut-direction adjustable, tool rests, set on the horizontal beam, or the port, to cut a work-piece horizontally by means of a horizontal linear reciprocating motion of the driving device, to machine with conventional vertical machining to perform further obverse and reverse cross machining, layer by layer, to prevent the residual stress of the working piece, or to perform grinding, planing, milling and polishing operations on a stepped strip shape work-piece.

Description: This invention relates to apparatus for machining a workpiece by grinding, milling and polishing whereby residual stresses within the workpiece are reduced. There are numerous known apparatuses which provide for the grinding, milling and polishing of workpieces. These apparatuses permit such work to be performed on workpieces which are both stationary and moving. Examples of such apparatuses are grinding centres, as well as the more conventional grinding machines, and the methods in which they are used. While useful for their purposes, the use of such apparatuses for working on stationary workpieces presents particular problems. Specifically, where stationary workpieces are involved, internal residual stresses can build up in the workpieces, these stresses being generated by the working tool (e.g. a grinding wheel). These internal residual stresses can, in turn, result in a flow, or other deformation, of the material in the workpieces. Such deformed workpieces are useless, resulting in losses of time and material. One known apparatus for grinding comprising the pre-characterising features of claims 1 and 2, respectively, is disclosed in CH-A-136984. The aim of the present invention is to provide an apparatus for grinding, milling and polishing a stationary workpiece while reducing, or substantially eliminating, the flow or deformation of the material therein. The present invention provides apparatus for machining a workpiece by grinding, milling and polishing whereby residual stresses within the workpiece are reduced, the apparatus comprising: a machine body; a bench for supporting the workpiece and for moving the workpiece longitudinally along the machine body; a support frame having a portal structure and mounted on the machine body; a transverse tool guide rail carried by the support frame; a tool carriage movable along the tool guide rail transversely across the machine body; a rotatable machine tool carried by the tool carriage; means for driving the machine tool; wherein relative movement between the machine tool and the workpiece in transverse and longitudinal directions are brought about by bi-directional movement of the tool carriage and movement of the bench along the machine respectively; characterised in that the machine tool rotatable about a horizontal axis and is angularly adjustable in 90° steps about a vertical axis for cutting operations directed in a transverse direction across the machine body and in a longitudinal direction along the body; and a locking device being provided for locking the machine tool in a selected angular position. The invention also provides apparatus for machining a workpiece by grinding, milling and polishing whereby residual stresses within the workpiece are reduced, the apparatus comprising: a machine body; a bench for supporting the workpiece and for moving the workpiece longitudinally along the machine body; a support frame having a portal structure and mounted on the machine body; at least one transverse guide rail carried by the support frame; a first tool carriage and a second tool carriage, each carriage being movable along said at least one transverse guide rail transversely across the machine body; a first rotatable machine tool carried by the first tool carriage; a second rotatable machine tool carried by the second tool carriage; and means for driving the first and the second machine tools, wherein relative movement between the first machine tool and the workpiece in a transverse direction is brought about by bi-directional movement of the first tool carriage along said at least one transverse guide rail, and relative movement between the second machine tool and the workpiece in a longitudinal direction is brought about by bi-directional movement of the bench along the machine; characterised in that the first machine tool is rotatable about a horizontal longitudinal axis for cutting operations directed in a transverse direction across the machine body, and the second machine tool is rotatable about a horizontal transverse axis for cutting operations directed in a longitudinal direction along the machine body. The invention will now be described in greater detail, by way of example, with reference to the drawings, in which:- FIG. 1 is a perspective view of a first embodiment of the apparatus of the present invention, wherein the apparatus is incorporated into a grinding, milling or polishing centre; FIG. 2 is a perspective view of a second embodiment of the apparatus of the present invention, wherein the apparatus is incorporated into a grinding, milling or polishing centre; FIG. 3 is a perspective view of a third embodiment of the apparatus of the present invention, wherein the apparatus is incorporated into a grinding, milling or polishing centre; and Tables 1 to 6 are flow charts of the use of the apparatus of the invention. Referring to the drawings, FIGS. 1 - 3 show machining apparatus 10 which includes a bench 11 which supports a workpiece 1. A first (horizontal) working tool guide rail 12 is supported above the bench 11 by a support frame 13. A first (horizontal) carriage 14 is horizontally slidingly carried by the guide 12 for transverse movement of the carriage 14. Ball bearings, pneumatic membranes or other mediums well known to those skilled in the art may be provided to facilitate the sliding movement of the carriage 14 along the guide 12. The carriage 14 supports a second (vertical) carriage 15 which, in turn, carries a working tool 16. This tool 16 may be a grinding tool, such as a grinding wheel, or any other conventional or unconventional tool, such as a polishing wheel, a milling wheel or a cutting tool which are well-known to those skilled in the art. In this fashion, the tool 16 may contact the top of the workpiece 1 for performing work operations on the workpiece in a transverse plane, such as the facing off, grinding, milling or polishing of the top of the workpiece. The tool 16 is rotatable about a horizontal axis, and is angularly adjustable in 90° steps. It can, therefore, be moved from the position shown in full lines to the position 16' shown in phantom lines for performing work operations in the longitudinal direction. The movement of the carriages 14 and 15, as well as the operation and movement of the tool 16, can be controlled by an operator from a control panel 17. Tables 1 to 4 are flow charts illustrating different operational cycles of the apparatus of Figure 1. Here, it should be noted that the "horizontal" direction is the transverse direction, and that the "vertical" direction is the longitudinal direction. Figure 2 shows a modified form of the machining apparatus of Figure 1. Accordingly, like reference numerals will be used for like parts, and only the modifications will be described in detail. Thus, the apparatus of Figure 2 includes two carriages 14a and 14b, each of which is horizontally slidingly carried by the guide 12 for transverse movement. Each carriage 14a,14b supports a respective working tool 16a,16b. The tool 16a is arranged to contact the top of a workpiece 1 for performing work operations on the workpiece in a transverse plane, and the tool 16b is arranged to contact the top of the workpiece for performing work operations in a longitudinal plane. Table 5 is a flow chart illustrating an operational cycle of the apparatus of Figure 2. Here again, it should be noted that the "horizontal" direction is the transverse direction, and that the "vertical" direction is the longitudinal direction. Figure 3 shows another modification of the machining apparatus of Figure 1. Here again, therefore, like reference numerals will be used for like parts, and only the modifications will be described in detail. Thus, the support frame 13 of the apparatus of Figure 3 carries a pair of longitudinally-spaced horizontal working tool guides 12a and 12b. Each of the guides 12a,12b supports a respective carriage 14a,14b, each of which is horizontally slidingly carried by its respective guide for transverse movement. Each carriage 14a,14b supports a respective working tool 16a, 16b. The tool 16a is arranged to contact the top of a workpiece 1 for performing work operations on the workpiece in a transverse plane, and the tool 16b is arranged to contact the top of the workpiece for performing work operations in a longitudinal plane. Table 6 is a flow chart illustrating an operational cycle of the apparatus of Figure 3. Here again, it should be noted that the "horizontal" direction is the transverse direction, and that the "vertical" direction is the longitudinal direction.

Claims: Apparatus for machining a workpiece (1) by grinding, milling and polishing whereby residual stresses within the workpiece are reduced comprising: a machine body; a bench (11) for supporting the workpiece and for moving the workpiece longitudinally along the machine body; a support frame (13) having a portal structure and mounted on the machine body; a transverse tool guide rail (12) carried by the support frame; a tool carriage (14) movable along the tool guide rail transversely across the machine body; a rotatable machine tool (16) carried by the tool carriage; means for driving the machine tool; wherein relative movement between the machine tool and the workpiece in transverse and longitudinal directions are brought about by bi-directional movement of the tool carriage and movement of the bench along the machine respectively; characterised in that the machine tool is rotatable about a horizontal axis and angularly adjustable in 90° steps about a vertical axis for cutting operations directed in a transverse direction across the machine body and in a longitudinal direction along the body; and a locking device being provided for locking the machine tool in a selected angular position. Apparatus for machining a workpiece (1) by grinding, milling and polishing whereby residual stresses within the workpiece are reduced comprising: a machine body; a bench (11) for supporting the workpiece and for moving the workpiece longitudinally along the machine body; a support frame (13) having a portal structure and mounted on the machine body; at least one transverse guide rail (12 or 12a, 12b) carried by the support frame; a first tool carriage (14a) and a second tool carriage (14b), each carriage being movable along said at least one transverse guide rail transversely across the machine body; a first rotatable machine tool (16a) carried by the first tool carriage; a second rotatable machine tool (16b) carried by the second tool carriage; and means for driving the first and the second machine tools, wherein relative movement between the first machine tool and the workpiece in a transverse direction is brought about by bi-directional movement of the first tool carriage along said at least one transverse guide rail, and relative movement between the second machine tool and the workpiece in a longitudinal direction is brought about by bi-directional movement of the bench along the machine; characterised in that the first machine tool is rotatable about a horizontal longitudinal axis for cutting operations directed in a transverse direction across the machine body, and the second machine tool is rotatable about a horizontal transverse axis for cutting operations directed in a longitudinal direction along the machine body. Apparatus according to claim 2, wherein said at least one transverse guide rail includes first and second transverse guide rails (12a, 12b), wherein the first tool carriage (14a) is carried by the first transverse guide rail, and the second tool carriage (14b) is carried by the second transverse guide rail. Apparatus according to any one of the preceding claims, further comprising means for raising and lowering the or each transverse tool guide rail (12 or 12a, 12b).

Inventors: YANG TAI-HER, YANG, TAI-HER
Applicants: YANG TAI HER, YANG, TAI-HER
Application year: 1991
Main classification: B23Q1
IPC codes: B23Q1, B24B7