GB2291983A - Machine tool control system - Google Patents

Abstract

A numeric control machine tool control system wherein the tool is capable of machining a number of different part types through a sequence of operations wherein data indicative of the sequence of operations required to machine each of a number of different part types is stored 33, 34, 35, the type of the part to be machined is input 31 and the data required to machine that part type is output from the memory 37 and used to form a program at 38 by which the tool is controlled to produce the required part type. The identity of the part to be machined may be input as a code which includes a key portion relating to the general character of the part and a supplementary portion relating to specific characteristics of a particular part to be machined. The part code may include a check portion to ensure that the code does not contain an error. A system is also disclosed wherein a drawing of the part to be machined is generated rather than the control program itself. <IMAGE>

Description

"Machine Tool Control Systems" This invention relates to machine tool control systems for controlling a machine tool so as to cause the machine tool to apply a sequence of machining operations to a part to be machined.

CNC (computer numeric controlled) machine tools are known which can be programmed to apply a number of machining operations in sequence in order to produce a machined part of a required form. Such machines include horizontal machining centres, turning centres and grinding machines. The setting up of such machines to enable a particular machined part to be produced repetitively is relatively complicated since it requires the production of drawings of the machined part showing the relative positions and dimensions of the various part features, and the appropriate programming of the machine tool to apply the required sequence of machining operations to reproduce these features.However, once an appropriate machine tool programme has been produced, it is a straightforward manner to apply this to the machine tool so as to cause the appropriate machined part to be produced as and when required.

CNC machined tools have therefore been widely used for machining of parts which are produced on a repeat basis so that it is worthwhile programming the machine to produce the part. However there are many applications in which a large number of different parts may need to be machined which nevertheless have many similarities in their structure so that all the parts can be produced by means of similar machining operations. Currently, if such parts are to be produced by a CNC machine tool, it is necessary to produce a separate machine tool programme for each part, and this is time-consuming and means that each part can only be produced after the machine tool has been specifically programmed to produce that part or an existing programme has been modified to produce the part.

Furthermore, if a minor modification is to be made to all the parts, the programme for each part must be separately modified and proved, and this is also time-consuming.

It is an object of the invention to provide a control system for a machine tool which enables a number of parts of broadly similar form but of a number of different types in terms of their structure to be machined without requiring a separate set-up procedure for programming of the machine tool to produce each part type.

According to the present invention there is provided a machine tool control system for controlling a machine tool so as to cause the machine tool to machine parts of a number of different part types which the machine tool is capable of machining under control of the control system, wherein the control system comprises a part code input for receiving a part code indicative of a selected part type to be machined, a part data memory for storing, for each of the different part types, data indicative of a sequence of machining operations required in machining of a part of that type and for outputting, in dependence on the part code supplied to the part code input, data indicative of a sequence of machining operations for machining of the selected part type, and a program generated for producing, for each of the different part types, a control program in dependence on the data outputted from the part data memory for causing the machine tool to carry out the required machining operations for machining of the selected part type.

Such a control system may be used to programme a conventional CNC machine tool to cause the machine tool to carry out the required sequence of machining operations for machining of a part type which has been selected on the basis of its part code, so that the machine tool may be caused to produce a series of different part types in dependence on their different part numbers, without it being necessary to separately set up the machine tool to produce each part type.

This is possible because each part which is to be produced is assigned a distinctive part number which may be referred to as "a talking part number" and which is indicative of the detailed structure of the part, and because the machining of each part type is performed in a modular manner with each module representing a machining operation or a series of machining operations which is characterised by data obtained from the part data memory in dependence on the part number. The control system categorises each of the different part types which are to be machined by a series of module codes which can be used to apply the corresponding machining operations to produce a part of the required shape.Since the different part types will have various features in common all the parts can be produced by a combination of module codes selected from a limited number of possible module codes each of which characterises a different machining operation or series of machining operations.

Since the machining operations to produce each part type are automatically controlled by the control system, the machine tool can be operated by unskilled labour. Furthermore a series of batches of different part types may be produced with a high level of machining accuracy and with a high level of variation in part detail as between the different part types, and with zero setting time being required for production of each new part type.

Since each part type is produced by a series of modules representing machine operations, it is possible for a minor modification to be made to all the part types simply by modifying the appropriate module, without the need for lengthy modification and proving of the programme for each part type.

In this context the term "part type" is to be understood as meaning a part of a particular construction or a series of parts of similar construction differing only in certain details, such as the position and/or type of one or more apertures or ports.

Preferably the part code input is adapted to receive a part code comprising a key portion which serves as a key for accessing data in the part data memory for machining of the selected part type, and at least one supplementary portion indicative of at least one supplementary feature to be applied to the part during machining. Thus different parts of the same part type may be differentiated in form by the at least one supplementary feature applied during machining.

In this case it is preferred that the program generator is adapted to produce the control program partially in dependence on said at least one supplementary portion of the part code so as to cause said at least one supplementary feature to be machined by the machining operations for machining of the selected part.

The part code input may be adapted to receive a part code incorporating a parameter portion which may be used to calculate at least one parameter relating to a feature to be applied to the part during machining. Since the parameter portion is used to directly calculate the corresponding part parameter, it is possible to vary the part parameter by appropriately changing the part number without any necessity for the control system to be programmed, for example by means of an appropriate look-up table, to allow for such variation.

The part code input is advantageously adapted to receive a part code incorporating a check portion and to perform a checking operation utilizing the check portion and the remainder of the part code in order to check that the part code does not contain an error.

Furthermore the part data memory is preferably adapted to store a plurality of data entries each of which comprises a key portion which serves as a key for accessing data in the part data memory for machining of the selected part type and a machine operation portion comprising a series of module codes characterising a series of machine operations required for machining of the selected part type. The key portion conveniently corresponds to the key portion of the part code which is supplied to the part code input.

Furthermore the part data memory may be adapted to store a plurality of data entries each of which incorporates at least one supplementary portion indicative of a dimension characterising the selected part type or at least one supplementary feature to be applied to the selected part during machining.

In addition a supplementary data memory may be provided for storing a plurality of data entries each of which is indicative of at least one machining operation for machining of at least one supplementary feature to be applied to the part type and for outputting to the program generator, in dependence on the part code supplied to the part code input and the corresponding data in the part data memory, data indicative of at least one machining operation for machining of at least one supplementary feature.

The program generator may be adapted to incorporate in the control program instructions, dependent on both said at least one supplementary portion of the part code and the selected data entry, for determining the position and type of at least one supplementary feature to be machined.

The invention also provides, in combination, a machine tool which is programmed so as to be capable of carrying out a number of different machining operations, and a machine tool control system as defined above for controlling the machine tool to cause the machine tool to machine parts of a number of different part types, as selected by input of the appropriate part codes, by carrying out in sequence the programmed machining operations required for machining of each selected part type.

According to the present invention there is provided a method of controlling a machine tool so as to cause the machine tool to machine parts of a number of different part types which the machine tool is capable of machining under such control, wherein the method comprises entering a part code indicative of each part type to be machined so as to select, for each part type, a part data entry indicative of a sequence of machining operations for machining the part type from amongst a plurality of data entries indicative of sequences of machining operations for machining the different part types, and outputting the selected part data entries to a program generator for producing control programs for controlling operation of the machine tool so as to cause the machine tool to carry out the required machining operations for machining of the different part types.

The invention also provides a method of controlling a drawing generator in a precisely similar manner so as to cause the drawing generator to produce drawings of a number of different part types which the drawing generator is capable of producing under such control.

In order that the invention may be more fully understood, a machine tool control system in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1A and 1B are end and side views of a first part to be produced by the system; Figures 2A and 2B are end and side views of a second part to be produced by the system; and Figure 3 is a block diagram of the system.

Figures 1A and 1B are end and side views of a machined part 1 which is a spool valve body having a part code lVPB-14-J1J24 and having a main spool bore (not shown) extending therethrough along a centre line 2. The body 1 has a milled back face (not visible in the figures), a milled face 4 at which the main spool bore opens, and a milled double side port face 6 which are produced by a series of machining operations under control of the system as will be described in more detail below with reference to Figure 3. A priority port 7 and an excess port 8 are formed in the side of the body 1 so as to intersect the main spool bore. Furthermore the body 1 has a flanged base 3 through which four bolt holes 5 extend.

Figures 2A and 2B show similar views of a spool valve body 10 which is of a different type to the spool valve body 1 of Figures 1A and 1B but which can be produced by means of the same control system. In this case the part has the part code lVPB-07-JlJ2L, and, instead of having a double side port arrangement, the body 10 has a priority port 11 extending through a milled end port face 12 and an excess port 13 extending through a milled side port face 14.

As will be apparent from the following description the control system is capable of producing either of the valve bodies 1 and 10 described, or any of a number of other valve body types, by means of a series of machining operations which are controlled by the system so as to produce not only the machined faces and bores and ports specifically referred to above but also various other features of the valve body shape.

Referring to Figure 3, in order to control the machine tool to produce a particular part, such as the spool valve body 1, the part code indicative of that part, e.g. lVPB-14-J1J24, is entered into a part code input 31 by way of a keyboard or automatically from a job schedule program. It is important that the part code is a so-called talking part code, that is that it consists of characters or groups of characters which define various structural features of the part in such a way that both the overall structure of the part and the individual structural features of the part are uniquely defined by the part code.

Thus, in the example given, the first three characters, e.g. 1VP, denote the frame size of the part, the fourth character, e.g. B, denotes the component type (e.g. valve body), the next two characters starting at the sixth character, e.g. 14, denote the body type, the next two characters starting at the ninth character, e.g. J1, denote a priority port type, the next two characters starting at the eleventh character, e.g. J2, denote the excess port type, and the final character is a check character.

The part code is then passed to a part code validation unit 32 which checks that the part code is of an acceptable format, and in addition carries out a check procedure which involves a numerical calculation based on the characters present in the part code and using conversion tables to obtain numerical equivalents for those characters which are alphabetical letters, and comparison of the result of this calculation with the check character.

If the part code has been correctly entered the result of the calculation should correspond to the check character.

Assuming that the part code has been validated the first three characters and the sixth and seventh characters (the key portion) of the part code denoting the frame size and the body type, e.g. 1VP, 14, are used to access a data file VLVBODY.DAT33 in a part data memory 34 which serves as a look-up table. This file 33 incorporates a respective data entry for each different part type (frame size and body type) in the range of parts which can be produced under control of the system, and the entry corresponding to the part code in question is: lVP,14,21.0,D,D,010,030,043,053,074,090.

The various items in this data entry are as follows.

The first two items, e.g. lVP,14, correspond to the key portion of the part code and are distinctive of the selected data entry in the file which also includes data entries for a number of other body types, both of lVP frame size and 2VP frame size.

The next item in the data entry, e.g. 21.0, indicates the start dimension to be used in the program for machining the part.

The next two items in the data entry, e.g. D,D, denote respectively the priority port position and the excess port position, where S denotes a side port, E denotes an end port and D denotes a double side port, so that, in the particular example given, both the priority port and the excess port are double side ports.

All the other items in the data entry are machining function module codes to be used in producing the program for machining the part. Thus, in the particular example given, the module codes 010, 030, 043, 053, 074, 090 characterise a number of machining functions taken from the following table of possible machining functions.

TABLE No. DescriDtion 010 mill back face mill side port faces if required or double side port face if required mill end port face if required mill face of spool bore machine priority port machine excess port 020 10.5 bolt holes - 2 off - drill 8 deep - RHS of vertical CL 4 holes through 030 10.5 bolt holes - 2 off - drill 8 deep - RHS of vertical CL 4 holes through 041 8.5 x 22 deep hole with 11 x 13 deep c/bore - LHS of vertical CL 043 8.5 x 22 deep hole with 11 x 13 deep c/bore - RHS of vertical CL 051 5 x 10.5 deep - RHS of vertical CL - below horizontal CL 053 5 x 10.5 deep - LHS of vertical CL - below horizontal CL 061 3 x 10.5 deep - RHS of vertical CL - above horizontal CL 063 3 x 10.5 deep - LHS of vertical CL - above horizontal CL 072 machine long relief valve cavity - RHS of vertical CL 074 machine long relief valve cavity - LHS of vertical CL 082 machine short relief valve cavity - RHS of vertical CL 084 machine short relief valve cavity - LHS of vertical CL 090 machine main spool bore RHS - right hand side LHS - left hand side CL - centre line all dimensions in millimetres Each possible data entry in the file contains a particular combination of such module codes, and in each case includes both the first and last module codes 010 and 090, one of the two module codes 020 and 030, and one of the two module codes 041 and 043. Some, but not all, of the data entries include one of the module codes 051, 053, 061 and 063 and one of the module codes 072, 074, 082 and 084.

The part data memory 34 also includes a supplementary data file VLVMACRO.DAT.35 which also serves as a look-up table and which contains a number of data entries corresponding to each permitted frame size, that is lVP or 2VP, and each permitted combination of priority port position and excess port position, that is SS, SE, ES, EE or DD, as determined from the selected data entry in the main data file 33. In the particular example given the relevant entry in this file is: lVPDD, 9902 where 1VPDD is the key by which the data entry is accessed, and 9902 is a macro routine value for use in the machine program for controlling the machining so as to correctly position the priority and excess ports.

A port type converter 36 is used to convert the two characters starting at the ninth character of the part code, e.g. J1, denoting the priority port type, and the two characters starting at the eleventh character of the part code, e.g. J2, denoting the excess port type into numerical values using a look-up table. In the particular example given the port types J1 and J2, denoting features such as the diameter and the form of tapping of the port, are converted to the numerical values 101 and 102 respectively.

Various values obtained from the data files 33 and 35 and the converter 36 are then supplied to a variable assigner 37 which assigns values to variables #554 to #566 according to the following logic.

#554 = start dimension from file 33, e.g. 21 #555 = the value representing the priority port position and type which is built up from a value representing the priority port position as obtained from the file 33, which takes a value of 17 where the position is S or D or 27 where the position is E, followed by the priority port value obtained from the converter 36, so as to give a variable value of 17101 in the example given denoting a double side J1 port.

#556 = a value representing the excess port position and type which is built up from a value representing the excess port position as obtained from the file 33, which takes a value of 17 where the position is S or D or 27 where the position is E, followed by the excess port value obtained from the converter 36, so that in the particular example given the value of the variable is 17102 representing a double side J2 port.

#561 = 010 from file 33 #562 = 030 from file 33 #563 = 043 from file 33 #564 = 053 from file 33 #565 = 074 from file 33 &num;566 = 090 from file 33 The module codes obtained from file 33 are assigned in sequence to the variables #561 onwards ignoring any blank spaces in the relevant data entry (which will be present where an entry does not include one of the codes 051, 053, 061 and 063 or one of the codes 072, 074, 082 and 084).

The assigned variables are then passed to a program generator 38 which substitutes the variables into a standard machine control program format to produce the required machine control program, only those variables which have been assigned a value being written into the program. The general program format and an example of a complete program as obtained using the values already given are set out below.

PROGRAM FORMAT :{Program number} {Product code} #554={Start dimension} #555={Priority port position + Priority port} #556=(Excess port position + Excess port} (*) #561={Value from sixth column onwards} #562=[Value from sixth column onwards] #579={Value from sixth column onwards} M98P{Macro routine} NlOOOOM98P#560 M98P9909 N99901M30 EXAMPLE COMPLETE PROGRAM lVPB- 14 -JlJ2 4 ::0001 (lVPB-14-JlJ24) #554=21 #555=17101 #556=17102 (*) #561=101 #562=030 #563=043 &num;564=053 #565=074 #566=090 M98P9902 N10000M98P#560 M98P9909 N99901M30 The machine control program generated in this manner by the program generator 38 may then be downloaded to the machine controller 39 under user control in order to cause the machine to produce the selected part. For convenience the generated program may be assigned a program number which may be used by the user to select that program when the appropriate part is to be produced, so as to avoid the necessity to generate the program as a separate operation whenever it is required for use.When the program is executed by the machine tool controller 39, the various instructions within the program are used to execute various machining sub-programs obtained from the machine program memory 40. Each sub-program serves to control a particular machining operation or series of machining operations.

Whilst, in the particular example given, the machine operator is only required to initially install the part in the appropriate position within the machine and subsequently remove the machined part, it is possible in other systems for the machining operations to be applied in two or more passes in which case the operator will be required to reposition the part between the passes.

If required the machine tool controller 39 can be programmed to produce successive batches of different parts according to a job schedule so that the machine operator can produce a continuous run of machined parts in which the required batches follow on in sequence, without any resetting of the machine tool controller being required between successive batches.

Claims (13)

1. A machine tool control system for controlling a machine tool so as to cause the machine tool to machine parts of a number of different part types which the machine tool is capable of machining under control of the control system, wherein the control system comprises a part code input for receiving a part code indicative of a selected part type to be machined, a part data memory for storing, for each of the different part types, data indicative of a sequence of machining operations required in machining of a part of that type and for outputting, in dependence on the part code supplied to the part code input, data indicative of a sequence of machining operations for machining of the selected part type, and a program generated for producing, for each of the different part types, a control program in dependence on the data outputted from the part data memory for causing the machine tool to carry out the required machining operations for machining of the selected part type.

2. A system according to claim 1, wherein the part code input is adapted to receive a part code comprising a key portion which serves as a key for accessing data in the part data memory for machining of the selected part type, and at least one supplementary portion indicative of at least one supplementary feature to be applied to the part during machining.

3. A system according to claim 2, wherein the program generator is adapted to produce the control program partially in dependence on said at least one supplementary portion of the part code so as to cause said at least one supplementary feature to be machined by the machining operations for machining of the selected part.

4. A system according to claim 1, 2 or 3, wherein the part code input is adapted to receive a part code incorporating a parameter portion which may be used to calculate at least one parameter relating to a feature to be applied to the part during machining.

5. A system according to any preceding claim, wherein the part code input is adapted to receive a part code incorporating a check portion and to perform a checking operation utilizing the check portion and the remainder of the part code in order to check that the part code does not contain an error.

6. A system according to any preceding claim, wherein the part data memory is adapted to store a plurality of data entries each of which comprises a key portion which serves as a key for accessing data in the part data memory for machining of the selected part type and a machine operation portion comprising a series of module codes characterising a series of machine operations required for machining of the selected part type.

7. A system according to any preceding claim, wherein the part data memory is adapted to store a plurality of data entries each of which incorporates at least one supplementary portion indicative of a dimension characterising the selected part type or at least one supplementary feature to be applied to the selected part during machining.

8. A system according to any preceding claim, wherein a supplementary data memory is provided for storing a plurality of data entries each of which is indicative of at least one machining operation for machining of at least one supplementary feature to be applied to the part type and for outputting to the program generator, in dependence on the part code supplied to the part code input the corresponding data in the part data memory, data indicative of at least one machining operation for machining of at least one supplementary feature.

9. A system according to any preceding claim, wherein the program generator is adapted to incorporate in the control program instructions, dependent on both said at least one supplementary portion of the part code and the selected data entry, for determining the position and type of at least one supplementary feature to be machined.

10. In combination, a machine tool which is programmed so as to be capable of carrying out a number of different machining operations, and a machine tool control system according to any preceding claim for controlling the machine tool to cause the machine tool to machine parts of a number of different part types, as selected by input of the appropriate part codes, by carrying out in sequence the programmed machining operations required for machining of each selected part type.

11. A method of controlling a machine tool so as to cause the machine tool to machine parts of a number of different part types which the machine tool is capable of machining under such control, wherein the method comprises entering a part code indicative of each part type to be machined so as to select, for each part type, a part data entry indicative of a sequence of machining operations for machining the part type from amongst a plurality of data entries indicative of sequences of machining operations for machining the different part types, and outputting the selected part data entries to a program generator for producing control programs for controlling operation of the machine tool so as to cause the machine tool to carry out the required machining operations for machining of the different part types.

12. A machine tool control system substantially as hereinbefore described with reference to the accompanying drawings.

13. A method of controlling a machine tool substantially as hereinbefore described with reference to the accompanying drawings.