DE2010481A1 - Method and device for numerical table path control of a large number of controllable machine axes - Google Patents

Description

Method and device for numerical path control of a large number of controllable machine axes The invention relates to a method and to a device for carrying out the method for numerical path control a multitude of controllable machine axes which form several control groups and these groups are installed on one or more machines and each controllable machine axis from a data processing system (hereinafter referred to as DVA) Receives base information.

F3for numerical controls of machine tools, such as Milling and turning machines or drilling machines, a distinction is made between two types, namely those soft either a positioning control or a path control notify. By means of the positioning control, you can specify with a high degree of accuracy Working points are approached one after the other. The path the tool takes to approach that describes the points is irrelevant here. Such positioning controls are therefore preferably used in drilling machines. The path control, however, comes preferably used in lathes and milling machines in which the workpiece machined during a movement of the machine table or the tool holder will. Here is the path the tool and / or workpiece takes between two points no longer travels arbitrarily, but depending on the design.

The invention finds application for such machines of the latter Art. The distance unit for the infeed movement of the tool and / or workpiece is usually 1 to in numerically tap-controlled machine tools of this type 10 / um. It is understandable that with large workpieces a correspondingly large Number of distance units and thus also of weighing data for controlling the workpiece or the tool are required. It must be taken into account here that in the case of spatial Contouring controls for each step three or more coordinate values or coordinate differences are required for the advance of the object from the point to the new point. In the extreme must be every shift by a distance unit, e.g. from one / um to a few hundred / um triggered by a special command. The amount of data required for this is in general very large, usually magnetic tapes for their storage tion can be used. Such an intermediate storage of the control values is in the generally not necessary, but then every machine must have a so-called interpolator to be inflicted. If several machines of the same type are in operation, it is - as known - more economical to provide the interpolator only once and use it to be used one after the other to generate the control signals for the various machines. In this case, the control signals for the individual machines are on magnetic tape stored and fed from there to the bus unit of each machine. The control units In this case they do not interpolate, they only distribute those from the bands read-in information to the axes of the machines. Depending on whether the interpolator is permanently assigned to the machine or whether several machines share one If you have an interpoiator, one speaks of an inner or an outer internolator.

The use of magnetic tapes is, however, in the rough workshop operation controversial because the tapes are not sufficiently secure against interference and damage must be shielded. For the rest it is necessary to have several machines of the same type to be used in order to be able to use the external interpolator in a meaningful way. at Use of an internal interpolator for every numerically controlled machine tool the effort increases by this unit and the additional data carriers (e.g. Punched tape) along with the associated reading devices.

The invention is based on the task of generating a plurality of numerically controllable machine axes, which form several control groups, these groups are installed on one or more machines, by means of a central interpolator to control. Furthermore, the device should be largely insensitive to external factors Influences and flexible in adapting to the type of machine to be controlled selenium. The performance of a DVA should also be exhausted and at the same time the control effort on the groups or machines is kept to a minimum will.

Based on a method for numerical path control of a Numerous controllable machine axes, which form several control groups and these groups are installed on one or more machines and each controllable If the machine axis receives information from a DVA (computer), this exists Method according to the invention in that one of the bases determined by the fWA of the trajectories for the individual groups in series during a reading cycle retrieves and feeds it to a central interpolator common to all groups, the a pulse sequence from the support points for each controllable machine axis of each group determined by linear interpolation of the interpolation points and these pulse trains all control units the controllable flat machine axes separately and outputs at the same time during a time interval common to all groups, furthermore, the cycle times of reading the interpolation points into the central interpolator and the cycle times for reading out the pulse trains to be sent to the control units staggered without overlap.

The DVA - a data processing system with additional devices - calculates the track joke points for a number of red groups of controllable machines on machines Machine axes.

This interpolation point information is sent to the central interpolator for the individual groups of the controllable machine axes in series during a reading cycle written in a Sneicher of the central interpolator. Thus the computer generates a high computing speed is required. According to the size of the information stored is provided by the centrafinterpolator for each axis of each connected machine or group a pulse train. These impulse sequences either, e.g. with With the help of a stepper motor, a machine slide or this pulse train is compared with a second pulse sequence that occurs when the machine slide moves or a Werkeeuges arises by scanning a scale. Through the determined The respective drive can make the difference between the pulse trains in relation to its infeed speed be managed. Also other known methods for setting the path of the tool or workpiece are possible. So that this computer does not have to do Umlormoperationen is loaded, the information pertaining to the program will be different DVA dual encrypted.

Based on known devices for numerical path control a large number of controllable machine axes, with one or more machine axes with their associated control units and interpolators form control groups and these Groups are installed on one or more machines, the Invention formed device in that they have a DVA and a connected, linear interpolating central interpolator providing pulse trains for all control units and the latter has a control output for each machine axis to which the control lines leading to the control units of the respective machine axes are connected, with those for controlling the other machine functions and the Hili's devices, in particular the tool changing devices, the coolant pumps or valves as well as the measuring and feedback devices, serving control lines are directly connected to the DVA. Through this inventive device for numerical path control of a large number of controllable machine axes is the otherwise required effort significantly reduced. The known ones are omitted Installation of buffer storage and computing facilities on every machine Or the like. Which are now only contained once in the central interpolator. The central interpolator is in the NShe of the computer and is therefore withdrawn from workshop influences and can also be maintained together with the computer.

This ensures reliable operation of the system.

Further details of the inventive method and the device for numerical path control of a large number of controllable machine axes will be explained in more detail with reference to the drawings.

According to Figure 1, there are three control groups 1, 6 and 3, for example provided by two milling machines and a lathe, their controllable machine axes X1m Y1, Z1 and X2m Y2 as well as X3, Y3 and U3 operated by control units 11, 12 and 13 will. The tools 14 and 24 are stationary in the present case, for example designed as an end mill. In the event of the control group according to figure 3 should e.g. in a cylindrical workpiece 31 a winding around the workpiece Groove 32 are cut. Here the tool 33 is in directions X3 and X3 Y3 is movable by means of the control units 54, 35, whereas the workpiece 31 is also movable constant rotation speed U. is driven by a control unit 36. All controllable machine axes or

their control units are via lines 15, 16, 17 and 25, 26, 27 and 37, 38, 39 with a central interpolator 4 in connection. The central interpolator has corresponding outputs 41, 42, 4, etc. for each machine axis. In the present case Case receives the central interpolation gate 4 from a computer 5 base information, in series for all control units of the machine axes of groups 1, ,, 3 etc. The computer 5 in turn receives the programs for controlling the machines either from another DVA that stores and distributes the control programs or gets them saved even after he has the control programs from a data carrier (e.g. a punched tape 8).

The command functions, e.g. B. Switching the tool drives on and off as well as the commands for tool change, cooling water inflow, are directly via the Lines 51, 52, 53 lead to the individual control groups of the machine axes, so that the intermediate interpolator of all additional arithmetic and control functions is relieved. The intermediate computer calculates the sections from the support point Support point for the movements of the axes, in this example X1, Y1, Z1 and Y2 as well as X3, Y3, U3 thus all connected machines resp.

Control groups 1, 2, 3 for each time interval and provides them.

A spatial movement is made up of the movements in direction of the individual axes together. The partial routes are called the path towards the respective Axis specified during the constant time interval, i.e. as speed. Changes in the speed of the individual machine can no longer be made Change the query frequency as with individual controls, since the query frequency heEi is constant in all connected nasains. The change in the feed rate reduction is therefore done by conversion. The conversions, like all, are non-linear Interpoiations, æ.B. the specifications for braking and acceleration as well as the specifications made by the computer for the consideration of the tool diameter. While of normal operations, however, change from one time interval to another only a few stretches, namely when braked, accelerated or from the intermediate computer is interpolated nonlinearly.

The structure of the central interpolator is shown in Figure 2 and consists essentially of the control unit 44, one in the dash-dotted field framed memory matrix 46, a frequency divider for scanning the memory matrix 47 and a data input buffer 40. In the present example the storage cells are formed as bistable multivibrators, the content of which is not destroyed when reading.

As can be seen in particular from Figure j, the rows of the memory matrix generally with a, the columns with b and the memory cells namely the bistable Flip-flops - denoted by S. The lines marked with small letters in the rows and columns are used to enter data, i.e. to write the matrix, where, on the other hand, the lines of lines and columns marked with capital letters serve for data output or for querying the matrix. As is known per se the values that are present on lines a1 to an, in the saliva cells S1i to S 5ni of that column i written which is addressed by the line bi will. The memory cells of those rows are connected by means of the lines i to bm read, which is addressed by one of the lines to Aj at the moment of a read pulse will. Each line Bi leads to the control of one of the axes of the connected Machines or groups. The "section" around which a tool axis, for example, is located should move forward during a certain time interval is in one of the columns B, with one of the columns B1 to bm assigned to each machine axis is. According to the invention it is provided here that the length of the time interval for all machines connected to the central interpolator equal it. The duration of the Time interval depends on the kt of the central interpolator. Everybody’s partial routes Axes of a machine or a group of axes are activated during a short period of the reading cycle written. The sections of the axes of another machine or group are written during another loophole. These values are taken from the intermediate computer calculated and provided. The writing in the central interpolator takes place in such a way that the controller 44 via line H from the channel of the computer Word - the size of a section for an axis of a machine or

Group - requests. This word is used by the intermediate computer selected line au to ant written into the buffer 48. The buffer becomes the word via the corresponding lines a1 to an in that selected column bi written. which is addressed by the column select shift register 45. In the present Trap transmits the line a # 'the sign. The line D, which from the controller leads to the column selector shift register, supplies the impulse for the latter, where, however, the clock for the column selection shift register is switched via the line T. will. Here, all axes of a group or a machine are used during a Gap of the reading clock written, otherwise the pulse trains generated during reading would be displaced. Lines E and F are used for feedback and displaying that the sizes of the partial distances of all axes of a machine transmitted have been.

The sampling pulse to the frequency divider 47, from which all lines of the columns are read line by line and at the same time. Of the reading clock coming from M is in the individual stages, namely A1 to An respectively halved in frequency. The flanks are offset so that the Impulses are excluded. The bit read - a clock pulse in the pulse train for a M. machine axis - depending on the sign, the lines Biv fibr die Forward or Bir for backward movement sets. The output frequency on the lines B may still have to be reduced in order to reduce the pulse frequency of the signal frequency for the control device of the axis concerned.

In the figure, 4 is a possible structure of a column, which for example is called via the channel bi from the column selection shift register, explained in more detail. The sign is converted into a, preferably as a bistable multivibrator, via the line aU trained memory written.

The other memory cells S1i up to this point are also correspondingly they were selected by the column selection shift register, written. above the channels A1 to An are each in the individual stages in their frequency halved interrogation pulse trains conducted. The lines A1 to An are in each case connected to an AND gate Q1 to Qn. The gate outputs are via a common line q connected to two AND gates Q (+), Q (-) The output of the gate Q (+) is on the signal line Biv and the output of the gate Q (-) is on the line Bir laid. If, for example, the sign is set in line Soi, then means this Reverse run for the relevant axis. Are e.g.

eight during a read interval when the storage cell S1i is activated Pulses passed and during the same reading interval over the line A3 two Read pulses performed, whereby - as already described - it is assumed that If the individual impulses are offset from one another, the Bir made ten pulses during the reading interval. In a coaster Zi (-) and Zi (+), the pulse frequency can be further scaled down if necessary.

Example: When reading out the memory 46 according to FIG the support point information supplied by the computer 5 at the memory outputs B1 up to B7 for three machines or groups with two, three and two controllable axes Pulse trains of a certain size are pending for B1 in column b1 of the memory the value 0 B2 "" b2 "" "" 4 B3 "" b3 "" "" 10 B4 "" b4 "" "" -11 B5 "" b5 "" "" 13 B6 "" b6 "" "" 6 B7 "" b7 "" "" -9 Dual encrypted and under Consideration that the first digit means the sign is given for Writing the memory in a four-digit matrix as follows: B1 0 = 00000 4 = 00100 10 = 01010 -11 = 11011 13 = 01101 B6 6 = 00110 B7 -9 = 11001.

According to FIG. 6, the memory 46 contains these in columns b1 to b7 written data. It is assumed that sd1 during a r gap of the reading clock only change the values in columns b1 and b2 or b3 to b5 or b6 and b7.

At the clock T of the column selection shift register 45, the columns b1 to b7 controlled one after the other. The writing takes place in the gap of the reading clock and for all axes of a machine or group. Lines E and F indicate that a11e partial routes or partial routes of all axes of a machine have been transferred are.

As in FIG. 5 zeitz, when reading from the are designed as a frequency divider Sampling passed over the lines A1 to A4 pulse repetition frequencies, which of Levels A1 to A4 are each halved. Run over line A1 according to FIG eight pulses and finally one pulse via line A4. It is up to everyone Outputs B1 to B7 a signal sequence during reading. In Figure 5 is at 48 11 shows this signal sequence corresponding to the value for axis B4, with Br indicates the minus sign.

In addition to the movement information, which the controllable machine axes received from the central interpolator, the machines usually need additional ones Information or commands, e.g. turning the coolant on and off, changing tools make or query the state of the machine, e.g. whether it is switched on or off is. This information occurs only sporadically, so that for its transmission another interface of the intermediate computer, e.g. the accumulator interface in a known DVA, can be used. A word output via this seam can be for a Computers with a twenty-four-bit word structure can be divided as follows: bit u -) the address of the machine, bit b - lu the function to be executed, hit 11 Flag that indicates that the addressed machine has received a response takes place, which must be waited before a new information about the interface is given.

Bit 1L - 23 information, e.g. number of the tool to be selected or a specific spindle speed.

The message sent from a machine to the computer has none prescribed structure; she interrupts the computer.

The programs for the numerically controlled machines are run in blocks, e.g. from a drum 7 connected to the computer 5. Likewise be Transfer the interpolation information in blocks from the computer to the central interpolator, where hi a BS zu ck the support point information for all axes and for a or comprises several time intervals. A block can be transferred to the central interpolator while the arithmetic unit of the computer carries out arithmetic operations, e.g. to create of the next block, is busy. In contrast, the switching and query information transferred word by word with the help of a computer program. A possible increase Figure 7 shows the output area in the computer for the interpolator. In one of two Change buffers, e.g. W1, are already used for several time intervals t1 to t5 written in the interpolation program calculated in advance, while they are read from the other buffer W into buffer 48 of the central interposer will.

7 claims 7 figures

Claims (7)

P a t e n t a n s p r ü c h e 1. Method for numerical path control a multitude of controllable machine axes which form several control groups and these groups are installed on one or more machines and each controllable machine axis from a data processing system - in the following DVA for short - receives support point information, which means that it is not shown e t, that the data point information of the trajectories determined by the DVA, for the individual control groups in series, during a read-in cycle a central interpolator common to all groups, which is derived from the base information for each controllable machine axis each group a pulse train through linear interpolation of the railway support points and these pulse trains to all control units of the controllable machine axes separately and simultaneously during all groups common, time interval outputs, furthermore the cycle times of reading the support point information in the central interpolator and the cycle times of the readout of the pulse sequences to be sent to the control units without overlapping in time offset. H. The method according to claim 1, characterized in - net that the sizes of the partially dry of all axes of a group provided by the intermediate computer writes to the central interpolator during a gap in the reading cycle. 3. The method according to claims 1 and 2, characterized in that g e k e n n -z e i c h n e t that all columns of the memory matrix of the central interpolator are row by row reads out at the same time and assigns a certain impulse sequence to each line and the pulse train frequency is halved step by step from line to line as well as the individual pulses the pulse repetition frequency offset from one another. 4. Device for performing the method for numerical path control of a plurality of controllable machine axes, one or more machine axes with their associated control units forming control groups and these groups are installed on one or more machines and where also the control units Using a DVA, their control information can be obtained from an interpolator, to which interpolation information is supplied, characterized in that it comprises at least one computer and an associated central interpolator that provides interpolating pulse sequences for all control units, and that the latter has a control output for each machine axis to which the control lines leading to the control units of the respective machine axes are connected, the reservoir lines serving to control the other machine functions and auxiliary devices, in particular the tool changing device, the coolant pumps or valves, and the measuring and return devices being connected to the computer . 5. Device for performing the method according to claim 4, characterized it is noted that the central interpolator has a controller (44) as well a column select shift register (45), one with the channel of the intermediate computer (5) Line-connected input buffer (48) and one from the controller called, designed as a frequency divider sampling (4 '/) and one from bistable Tilt mares consisting of a storage matrix (4ú). 6. Device according to claims 4 and 5, thereby g e k e n n -z e i c h n e t that every histable trigger stage has two Sni) of a Spite (bi) with an AND gate (Q) is connected and at each AND gate the associated scanning channel (Aj) and all AND gate outputs are connected to a common line (q) are and the latter lead over a Sign gate (Q (+), Q (-)) are connected to the column output channel or bin). 7. Device according to claims 4 to 6, characterized g e k e n n -z e i c h n e t that every column in the memory matrix of the central interpolator has one Machine axis is assigned.