The present invention relates to an automatically operated lathe and method for controlling the same.
A turning machine tool capable of performing an automatic turning process (referred generically to as an automatically operated lathe in this specification) may automatically carry out various turning processes in sequence or, if necessary, simultaneously, by causing a feed motion of various tools carried on a tool rest relative to a bar-shaped or disk-shaped workpiece to be machined, which is securely held in a spindle. Recently, an automatically operated lathe of a type (called an electronic-cam type) controlling a relative feed motion between a workpiece or spindle and a tool or tool rest by a machining command using a cam-reference data for successively directing tool positions as a function of cam rotation angles, has been provided.
In the electronic-cam type automatically operated lathe, an electric operating command following a predetermined cam curve is used, in place of a mechanical operation of a cam used in a traditional cam-installed automatic lathe, to automatically control a relative feed motion between the spindle and the tool rest. Accordingly, the electronic-cam type automatically operated lathe is capable of advantageously performing a relatively simple machining sequence in a short time, due to respective motions of tools carried on plural tool rests, which follow individual cam curves in a way similar to the conventional cam-installed automatic lathe. In particular, according to such an electronic-cam system, it is not necessary to provide many types of mechanical cams corresponding to the configurations of machined products, and it is possible to significantly reduce time and labor required for an initial set-up, which permits various kinds of products to be manufactured in very high productivity in comparison with the conventional cam-installed automatic lathe.
Also, in the electronic-cam type automatically operated lathe, even when the machine structure thereof is provided with a plurality of control axes along which the spindle and the tool rest are relatively operated, it is possible to prepare cam diagrams for the respective control axes on a common reference (i.e., a cam rotation angle), which advantageously makes it easier to program a synchronizing command of the control axes. Moreover, the operation of the control axes is individually and freely controllable, so that, in the case where various machining processes are successively performed by using plural tools, it is made easier to operate the tools so as to overlap in time, and thereby, it is possible to significantly reduce the time required for the entire machining process (i.e., one machining cycle) of the workpiece to be machined. Contrary to this, in the conventional NC lathe, it is generally difficult, from a viewpoint of machine and control structure, to perform a machining process of one tool until another tool reaches a stand-by position after finishing the machining process thereof, and thereby, the time required for one machining cycle inevitably includes the idle time of tools.
In the above-described electronic-cam type automatically operated lathe, the cam rotation angle as a reference for preparing the cam diagrams may be defined on the basis of a rotational frequency of the spindle. That is, a predetermined rotational frequency of the spindle is defined to correspond to a single rotation (360 degrees) of the cam, and tool positions are successively directed corresponding to the rotational frequencies of the spindle, so as to control the operation of the respective control axes. According to this structure, it is possible to individually control the operation of the plural control axes on the basis of a common reference defined by the rotational frequency of the spindle (normally, the rotational frequency of the drive source of the spindle) that is a mechanically operative component of the automatically operated lathe.
However, in this structure, the operation of the control axes cannot be controlled during a period when the spindle does not rotate. Therefore, it is difficult, in the automatically operated lathe performing an electronic-cam control on the basis of the rotational frequency of the spindle, to carry out, for example, a secondary process (e.g., a cutting process by a rotary tool) during a period when the spindle does not rotate, which can be carried out by a conventional multifunctional numerically-controlled (NC) lathe.
Also, the rotational frequency of the spindle may be varied, in general, due to a machining load applied to the spindle by, e.g., a cutting force during the machining process. In particular, in the structure wherein a drive force from a spindle drive source is transmitted to the spindle through a transmission mechanism such as a belt/pulley, the rotational frequency of the spindle drive source tends to become different from the actual rotational frequency of the spindle, when a slip is caused in the transmission mechanism by the machining load. In this case, in an electronic-cam control on the basis of the rotational frequency of the spindle drive source, the spindle and the tool rest are operated to perform the relative feed motion in accordance with the rotational frequency of the spindle drive source irrespective of the actual machining progress of the workpiece, which may cause deterioration of the machining accuracy.
An object of the present invention is to provide an automatically operated lathe capable of controlling a relative feed motion between a spindle and a tool rest in an electronic-cam system, and capable of exerting multifunctional properties for performing a secondary process during a period when a spindle does not rotate, as well as to provide a method for controlling such an automatically operated lathe.
Another object of the present invention is to provide an automatically operated lathe capable of controlling a relative feed motion between a spindle and a tool rest in an electronic-cam system, and capable of performing a high precision machining without being influenced from the variation of the rotational frequency of the spindle, as well as to provide a method for controlling such an automatically operated lathe.
To achieve the above object, the present invention provides in one aspect thereof a method for controlling an automatically operated lathe provided with at least one spindle and at least one tool rest, comprising providing each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of a cam-reference data directing a transfer position as a function of a cam rotation quantity; providing a plurality of pulse-train generating sources, each of which generates any pulse train; designating, with regard to each of the plurality of transfer position data, a pulse-train generating source for generating a pulse train defining the cam rotation quantity as one component of the cam-reference data, the pulse-train generating source being selected from the plurality of pulse-train generating sources; and processing each of the plurality of transfer position data provided in the form of the cam-reference data by using the pulse train generated through the pulse-train generating source as designated, to control a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, the method for controlling is provided, wherein the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes, and wherein the step of designating the pulse-train generating source includes designating the pulse-train generating source with regard to each of the plurality of transfer position data in relation to each of the plurality of control axes.
In the preferred embodiment, the method for controlling is provided, further comprising a step of designating a time-series allocation of the plurality of transfer position data in the sequence of machining programs, wherein the step of processing the transfer position data includes processing, in accordance with the time-series allocation as designated, each of the plurality of transfer position data provided in the form of the cam-reference data.
It is advantageous that the method further comprises a step of showing, in a form of a displacement diagram, each of the plurality of transfer position data provided in the form of the cam-reference data.
In this arrangement, the step of designating the pulse-train generating source may include designating, in association with the displacement diagram, the pulse-train generating source with regard to each of the plurality of transfer position data.
Also, the method for controlling may be provided, further comprising a step of designating a time-series allocation of the plurality of transfer position data in the sequence of machining programs on the displacement diagram, wherein the step of processing the transfer position data includes processing, in accordance with the time-series allocation as designated on the displacement diagram, each of the plurality of transfer position data provided in the form of the cam-reference data.
In this arrangement, a structure may be provided, wherein the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes, and wherein the step of designating the time-series allocation includes designating, on the displacement diagram, a synchronization between the plurality of transfer position data for respectively operationally controlling the plurality of control axes.
The plurality of pulse-train generating sources may include a spindle-pulse generating source generating a pulse train corresponding to a rotation of the at least one spindle.
Also, the plurality of pulse-train generating sources include an outside-pulse generating source generating a pulse train irrespective of an operation of the automatically operated lathe.
The present invention provides in one aspect thereof an automatically operated lathe, comprising a lathe bed; at least one spindle mounted on the lathe bed; at least one tool rest mounted on the lathe bed; a control device for controlling an operation of the at least one spindle and the at least one tool rest on the lathe bed; and a plurality of pulse-train generating sources, each of which generates any pulse train; the control device including an input section permitting entering of each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of a cam-reference data directing a transfer position as a function of a cam rotation quantity, and permitting a designation of a pulse-train generating source for generating a pulse train defining the cam rotation quantity as one component of the cam-reference data, with regard to each of the plurality of transfer position data, the pulse-train generating source being selected from the plurality of pulse-train generating sources; and a processing section processing each of the plurality of transfer position data entered through the input section in the form of the cam-reference data by using the pulse train generated through the pulse-train generating source designated through the input section, to thereby generate a control signal for controlling a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, an automatically operated lathe is provided, wherein the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes on the lathe bed, and wherein the input section of the control device permits a designation of the pulse-train generating source with regard to each of the plurality of transfer position data in relation to each of the plurality of control axes.
In the preferred embodiment, an automatically operated lathe is provided, wherein the input section of the control device permits an designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs, and wherein the processing section of the control device processes, in accordance with the time-series allocation designated through the input section, each of the plurality of transfer position data entered in the form of the cam-reference data through the input section.
It is advantageous that the control device further includes a display section displaying, in a form of a displacement diagram, each of the plurality of transfer position data entered through the input section in the form of the cam-reference data.
In this arrangement, it is preferred that the input section of the control device permits a designation of the pulse-train generating source with regard to each of the plurality of transfer position data, in association with the displacement diagram displayed in the display section.
Also, the structure may be provided, wherein the input section of the control device permits a designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs on the displacement diagram displayed in the display section, and wherein the processing section of the control device processes, in accordance with the time-series allocation as designated on the displacement diagram, each of the plurality of transfer position data entered in the form of the cam-reference data through the input section.
In this arrangement, it is preferred that the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes on the lathe bed, and that the input section of the control device permits a designation of a synchronization between the plurality of transfer position data for respectively operationally controlling the plurality of control axes, on the displacement diagram displayed in the display section.
The plurality of pulse-train generating sources may include a spindle-pulse generating source generating a pulse train corresponding to a rotation of the at least one spindle.
Also, the plurality of pulse-train generating sources may include an outside-pulse generating source generating a pulse train irrespective of an operation of the automatically operated lathe.
The present invention provides in one aspect thereof a control device for use in an automatically operated lathe provided with at least one spindle and at least one tool rest, comprising an input section permitting an entering of each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of a cam-reference data directing a transfer position as a function of a cam rotation quantity, and permitting a designation of a pulse-train generating source for generating a pulse train defining the cam rotation quantity as one component of the cam-reference data, with regard to each of the plurality of transfer position data, the pulse-train generating source being selected from a plurality of pulse-train generating sources as previously provided; and a processing section processing each of the plurality of transfer position data entered through the input section in the form of the cam-reference data by using the pulse train generated through the pulse-train generating source designated through the input section, to thereby generate a control signal for controlling a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, the control device is provided, wherein the input section permits an designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs, and wherein the processing section processes, in accordance with the time-series allocation designated through the input section, each of the plurality of transfer position data entered in the form of the cam-reference data through the input section.
It is advantageous that the device further comprises a display section displaying, in a form of a displacement diagram, each of the plurality of transfer position data entered through the input section in the form of the cam-reference data.
In this arrangement, it is preferred that the input section permits a designation of the pulse-train generating source with regard to each of the plurality of transfer position data, in association with the displacement diagram displayed in the display section.
Also, a structure may be provided, wherein the input section permits a designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs on the displacement diagram displayed in the display section, and wherein the processing section processes, in accordance with the time-series allocation as designated on the displacement diagram, each of the plurality of transfer position data entered in the form of the cam-reference data through the input section.