Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1998-02-18
2001-02-27
Grant, William (Department: 2786)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S160000
Reexamination Certificate
active
06195595
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for working a workpiece, which apparatus comprises drive means for rotating a carrier about an axis of rotation, a tool for working said workpiece, means for moving said tool in an x-direction and a y-direction with respect to said drive means, and a control unit comprising a memory for one or more control programs, wherein said control unit is arranged for controlling said moving means in accordance with a control program, in such a manner that said tool follows one or more desired paths for working the workpiece, and also to a method for storing a control program for such an apparatus and to a method for controlling such an apparatus.
Apparatus of the above kind are known in various embodiments thereof, and they may be adapted for working the workpiece, whether or not by removing stock. Known apparatus are for example lathes, forming lathes or the like. Usually a control program is stored in the memory in a teaching or programming phase in the known apparatus, after which the control unit controls the moving means in accordance with the control program in the production phase, so that the tool is moved in the desired path or paths along the workpiece, which is clamped in the apparatus, so as to carry out the desired working step on the workpiece. One problem that occurs with known apparatus is that when the tool is exchanged or worked, the tool contour and/or the position of said contour with respect to the axis of rotation no longer correspond with the contour and/or the position of the tool during the teaching or programming phase, in particular if the tool must be adjusted in advance outside the apparatus. Another problem is that when maintenance or repairs are being carried out on the apparatus, whereby the moving means are for example detached from the frame of the apparatus, it is virtually impossible to fix the moving means in exactly the same position in the apparatus again. In such cases a change actually occurs in one or more apparatus parameters that influence the control program, as a result of which the stored program can no longer be used. In that case it will be necessary to store the control program for the product in question in the memory anew in a teaching or programming phase.
In the mass production of large numbers of identical products, several apparatus of the above kind will usually produce the same workpiece. With the known apparatus a control program must be stored in the memory in a teaching or programming phase for each apparatus separately. This makes it virtually impossible to achieve an exactly synchronized same production time for all apparatus which produce the same product. This is a drawback, in particular if the worked workpieces from two or more apparatus must subsequently undergo further working in a common subsequent apparatus.
SUMMARY OF THE INVENTION
The object of the invention is to provide an apparatus of the kind referred to in the introduction, wherein the above drawbacks have been overcome in a simple and efficient manner.
In order to accomplish that objective the apparatus according to the invention is characterized in that the control unit is arranged for measuring at least one apparatus parameter, which apparatus parameter is stored at the (each) control program, wherein the control unit is arranged for comparing the stored apparatus parameter with the measured apparatus parameter, and wherein the control unit, if a difference is detected between the stored apparatus parameter(s) and the measured one(s), adapts the (each) control program in such a manner that the tool will follow the desired path(s).
The invention is based on the insight that by storing the apparatus parameters, such as the angle between the axis of rotation and one of the directions of movement, and/or the tool contour and the position of said contour with respect to the axis of rotation, in the control programme, said control programme is in fact made independent of said parameters. By having the control unit measure these parameters before a workpiece is worked in accordance with a control program, the control unit can establish the difference between the values stored at the control program in question and the measured values, and, if a difference is detected, adapt the control program so that the tool will follow the desired path or paths in spite of any such deviation. This means that a new teaching or programming phase for continuing the production in accordance with an already stored control program is no longer necessary when the tool is exchanged or worked. In addition, a control program which has been stored in a particular apparatus in a teaching or programming phase together with the associated apparatus parameter(s), can be used in other apparatus without any problem, whereby said control program can be adapted to the apparatus in question in a simple manner by having the control unit measure the apparatus parameter(s). All of the apparatuses will then have the same production time. Moreover, a teaching or programming phase is only required for one apparatus, after which the control program can be used for all other apparatuses which are used for producing the same product.
Another advantage of the apparatus according to the invention is furthermore the fact that a user of the apparatus can order a control program for the manufacture of a particular product from the manufacturer or from another supplier, which program can be stored in a teaching or programming phase on an available machine by the supplier, and subsequently be made available to the user.
Consequently the invention also provides a method for storing a control program for an apparatus for working a workpiece, which apparatus comprises drive means for rotating a carrier about an axis of rotation, a tool for working the workpiece, means for moving said tool with respect to said drive means in an x-direction and a y-direction, and a control unit comprising a memory for one or more control programs, wherein a working step is carried out on the workpiece in a teaching or programming phase, and one or more paths followed by the tool during the working of the workpiece are stored in the memory in the form of a control program for said moving means, characterized in that at least one apparatus parameter, preferably the angle between the axis of rotation and one of the directions of movement and/or the tool contour and the position of said contour with respect to the axis of rotation, is measured and stored in the memory.
The invention furthermore provides a method for controlling an apparatus for working a workpiece, which apparatus comprises drive means for rotating a carrier about an axis of rotation, a tool for working the workpiece, means for moving said tool with respect to said drive means in an x-direction and a y-direction, and a control unit comprising a memory for storing one or more control programs and at least one apparatus parameter, wherein said control unit is arranged for controlling said moving means in accordance with a control program, in such a manner that said tool follows one or more desired paths for working the workpiece, characterized in that at least one apparatus parameter is measured and compared with the stored apparatus parameter, and if a difference is detected between the stored apparatus parameter and the measured one, the (each) control program is adapted in such a manner that the tool will follow the desired path(s), whereby preferably the angle between the axis of rotation and one of the directions of movement and/or the tool contour and the position of said contour with respect to the axis of rotation are used as the apparatus parameters.
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Bahta Kidest
Grant William
Koehler, Esq. S.
Westman Champlin & Kelly P.A.
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