FR2480961A1 - METHOD FOR DIGITAL CONTROL OF A MACHINE TOOL - Google Patents

Abstract

A. DIGITAL CONTROL PROCEDURE FOR A MACHINE-TOOL. B. ORDERING PROCESS CHARACTERIZED IN THAT ALL THE DATA NECESSARY TO CALCULATE THE MOVEMENT OF THE TOOLS USING SEVERAL INPUT BUFFER MEMORIES ARE INTRODUCED INTO A CALCULATION UNIT, THE MACHINING DATA IS SUCCESSIVELY CALCULATED USING THE DATA AND THE CALCULATIONS ARE TRANSFERRED INTO THE MACHINING BUFFER MEMORY. C. THE INVENTION CONCERNS NUMERICALLY CONTROLLED MACHINE TOOLS.

Description

24, S96 1

  The present invention relates to a method of controlling a machine in which the movement of the machine is calculated automatically by introducing the shape of the machining and the final dimensions of the workpiece as well as the machining conditions by means of keys of the machine. a caliber forming part of the control panel, the machine being controlled

  according to the result of these calculations.

  Known machines with numerical control are

classified into three types.

  In the first type of machines, all the control data is introduced via perforated strips. In the second type, the data is introduced by

a keyboard.

  In the third type, real machining is performed

  and record the resulting data.

  The first two types require a detailed program of the movement of the device to be controlled using a particular digital coding; it takes a lot of work and time to prepare the punched tapes and has

  difficulties in adjusting the tools.

  In the third type, the skill of the user who actually does the work greatly influences subsequent operations and there are many disadvantages in the control so that this type of machines is not widely used. The present applicant has already proposed a device described in US Pat. No. 4,033,206 to overcome the drawbacks of known solutions. This device is characterized by the fact that the data is introduced by means of digital switches and not by bands, the number of input phases is reduced.

  of data and simplify the input operations.

  For this, the device allows to enter the machining data of the form and the finish of the form as well as the dimensions to be given to the roughing and the machining conditions as well as the

  replication mode of the tool that are the conditions set.

  This type of device solves all the problems

disadvantages of the prior art.

  The present invention aims to improve the

control of such a device.

  For this purpose, the invention relates to a control method characterized in that records the data necessary for the machining work in a microcomputer by reducing them to the minimum necessary for the machining of the shape and the finish of the form , while the various data actually needed during the execution of the work, such as the path of movement of the tool during coarse finishing and the path of movement of the tool during final finishing, are successively calculated using data stored in a microcomputer, the data processing associated with the various parts being done with a

minimum amount of recorded data.

  The control method according to the invention makes it possible to introduce in a simple manner data concerning the shape of the finish and the dimensions, this recording being done in the microcomputer which automatically calculates the coarse machining dimension and the coarse finish for

  perform the corresponding operations.

  The control method according to the invention makes it possible to make the machining of complex shape having concave parts

  and convex parts, and this in a simple way.

  The invention also relates to a method according to which the machining data intended to be introduced into the computer are corrected automatically according to the shape of the cutting edge of the machining tool, for

perform this machining.

  According to another characteristic, the invention relates to

  is a process that allows the operator to use the calculator to decide whether the shape of the cutting edge of the tool and the shape of the machining of the workpiece for which the data is

  introduced in the calculator, are appropriate or not.

  Depending on the process, one can execute in a way.

  specifies two successive machining operations with two types

  tools with different beak diameter.

  It is thus possible to facilitate the control of devices of this type, to make this command more

  accurate and improve the features.

  The present invention will be described in more detail with the aid of the accompanying drawings, in which: FIG. 1 is an example of a control panel for introducing the data necessary for machining according to the invention. FIG. 2 is a block diagram of an installation according to the invention; FIG. 3 shows the shape of the tip of a tool; FIGS. 4a show the various phases of a

  process in which the CPU calculator prepares a record

  very machining based on the data provided by the buffer

input.

  - Figure 5 is an example of the shape of the machining

  a machine working by copy.

  - Figure 6 shows how to find the rough finishing line from the shape of the finishing machining

on a copy machine.

  - Figure 7 shows a linear interpolation of a

copy machine.

  - Figure 8 shows the calculation of an intersection

a copy machine.

  Fig. 9 is a flowchart showing how to prepare a data set for coarse finishing during any machining step of a copying machine. - Figure 10 shows how to find the line of

  coarse finish on a copy machine.

  FIG. 11 is a flowchart showing how to prepare a data set for coarse machining on

a copy machine.

  - Figure 12 gives an example of a form of machining

of a cylindrical piece.

  - Figure 13 gives an example of a form of machining

open of a cylindrical part.

  FIG. 14 represents an example of a single-pass concave machining form for a cylindrical part according to FIG.

the invention.

  FIG. 15 shows a diagram of movement instructions of a tool for coarse machining of a cylindrical part. FIG. 16 is a geometric view showing how to find the starting point of coarse machining for a cylindrical part in the case of a concave shape at a

  only one passes for a conical part.

  FIG. 17 is a geometric view showing how to find the rough machining end of a cylindrical part in the case of a conical part. FIG. 18 is a geometric view showing how to find a coarse machining start painting of a cylindrical part in the case of a single concave part.

pass on a convex circle.

  FIG. 19 is a geometric view showing how to find the end of coarse machining on a

  cylindrical piece in the case of a convex part.

  FIG. 20 is a geometric view showing how to find the starting point of a coarse machining of a cylindrical part in the case of a concave part to a single

pass, on a concave circle.

  FIG. 21 is a geometrical figure showing how to find the end of coarse machining of a part

  cylindrical in the case of a concave part.

  - Figure 22 is a flowchart showing the application of

  a coarse machining control method of a part

  cylindrical in the case of a single pass concave portion.

  FIGS. 23 and 24 show the application of a cutting path for a coarse machining tool obtained by

  the coarse machining control method of a cylindrical part

  according to the flow chart of Figure 22.

  FIG. 25 is a flowchart showing a coarse machining control method of a cylindrical part

in the case of an open party.

  FIG. 26 shows a machining shape corresponding to a concave part with a single pass, making it possible to execute a coarse machining control of a cylindrical part during

  of a single phase according to the invention.

  - Figures 27, 28 show an interference between a

  tool and a form of machining, making machining impossible.

  - Figure 29 shows a known interpolation process

  used in cases of the impossibility of machining.

  - Figures 30 - 35 show the application of the method

of the invention to various forms.

  - Figure 36 is a flow chart that leads to the

  decision of the impossibility of machining.

  - Figure 37 is another flow chart that leads

  the decision of impossible machining.

  - Figure 38 gives an example of a form of machining with data entry in a control device. - Figure 39 is used on an enlarged scale of

  the cutting edge of a tool uses tools.

  - Figure 40 shows a machined part without compensation

the radius of the nozzle of the tool.

  - Figures 41, 42 show machined parts with

  compensation of the radius of the nozzle of the tool.

  FIGS. 43 and 44 show two successive phases executed using two types of tools according to the method

  Knife compensation tool.

  FIGS. 45, 46, 47 and 49, 50 show two successive phases executed using two types of tools according to FIG.

  control method of the invention.

  - Figure 48 is a flowchart showing the

  control method according to the invention.

  DESCRIPTION OF VARIOUS PREFERENTIAL EMBODIMENTS

  FIG. 1 shows an example of a control panel of a control device implementing the numerical control method according to the invention, showing the situation

  the invention in a very comprehensible manner.

  Reference 2 relates to the keys provided on the control panel 1, to determine the shape to be machined on the lathe; reference 3 relates to indicator lights to indicate to the user the type of data needed according to the shape of the machining provided by the keys. Keys and indicator lamps carry indications in the appropriate languages. The ten digit 4 keys are used

  to introduce numerical values according to the indica-

  witness lights 3. A touch of

  Table 5 is used for the microcomputer to output the start operation signal. The set key 6 is used to record data in the microcomputer after the input of the data using the keys 2 or 4. Key 7 "function as before" is used when

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  the following piece has a predetermined shape, so complex that it is necessary to introduce the machining data into the microcomputer, in certain phases rather than at a given moment and when the numerical values indicated by the indicator lamps 3 which light up at the moment in which to enter the data for the nth minor machining phase are the same numerical values for the same product as during the phase

  (7), the large-scale

  In the course of (n-1) machining phase, the same product is driven and concurently such quantities are displayed on an indicating device 16 which will be described later. Reference 8 relates to the correction key used to correct the data that comes

  to be fixed; reference 9 relates to an erase key

  all data used to erase all data entered into the microcomputer; the reference relates to an erase key of a machining phase, to erase the data entered in the microcomputer and

  which correspond to a machining phase.

  Reference 11 relates to a program key

  used to give calculation and recording instructions

  various data necessary for the order

  of the machine after entering the data

  cessaires; reference numeral 12 relates to an operating mode switch used to ensure the passage between the manual operation and the automatic operation of the lathe; reference 13 relates to a part switch used to read the part of the data on different workpieces,

  these data being registered in advance and corresponding to

  lay at the workpiece at this time, to allow automatic machining of the workpiece. Reference 14 relates to indicator lamps indicative of the state of the lathe; the reference

  concerning indicator lamps indicative of abnormal situations

  males, at the level of one of the different devices; the reference

  reference 16 concerns an indicator indicating the quantities of

  by means of the keys of the keyboard 4. There is further provided a group of switches shown in the right-hand part of FIG. 1, which serve to control the lathe by hand,

  The present invention relates to a method of

  command of a numerically controlled machine tool having a

such data input means.

  Figure 2 is an overall diagram of a circuit

  for the implementation of a control method according to the in-

  vention; in this diagram, the microcomputer 17 comprises a central processing unit CPU 18, a read-only memory 19, the

  input buffers 20 and a set of machining buffers 21.

  The turn 22 is connected to the microcomputer 17 Dar i-e-

  23 of the Do_- Machine tools with numerical co-band (also called NC machines) There are N input buffers 20 and the data of the corresponding part are introduced into each buffer. Entrance

  by setting the input switch which will be described later

  quently. The data to be entered in each buffer of

  tree 20 are classified into common data and operating phase data for each machining phase. The

  common data concern the original position (for

  dexter a tool) the finishing tolerance S and, as

  3, the cutting angle, the cutting exit angle 3 and the radius r of the tool nose or tip.

  for a given tool number. Phase data

  include the shape of the machining., the X and Z coordinates of a cutting point, the X and Z coordinates of a starting point, the X and Z coordinates of an end point or point of arrival, the radius R of a corner, the degree of cut

  the number m of the finishing tool, the number of the tool-

  coarse machining m ', the speed of rotation N and the vi-

  In addition, if the shape of the workpiece is too complex to introduce data relating to

  this form of machining at the instant of the control of the switching

  setting of the data entry 25 can be entered

  to obtain these data step by step. Each input buffer 20

  saves data up to n

  swimming. The assembly of machining buffers 21 consists of one.

  finishing pad, coarse finishing pad and coarse machining pad. The data relating to the path of

  movement of a tool during finishing machining, the

  min of moving the tool during rough finishing

  and the path of movement of a tool during rough machining

  The data calculated by the CPU 18 on the basis of the data entered in the input buffer 20 can be fed into the different buffers of the set 21. In addition there is only one set of machining buffers. 21 regardless of the number of input buffers 20 so that each time the type of workpieces can be modified and the data calculated by the CPU 18 on the basis of the data previously stored in the buffer input 20 associated with the workpiece, change, and cause the _cn'p data enrolled in the school 21. The re-ene 24 relates to a change of room switch designating a

  particular buffer among the N input buffers 20 in the

  which data should be recorded or read. The reference

  reference 25 relates to the data setting switch

  used to insert data into the data buffer.

  The reference 26 relates to an input data correction switch used to correct the data that has just been introduced by the input data adjustment switch.

  25. Reference 27 relates to an erase switch to-

  tal of input data to delete all data

  introduced in the input buffers 20. Reference 28

  identifies the machining data preparation switch used to control the CPU 18 and calculate on the basis of the data recorded in the input buffer 20 as well as to record the data obtained in the set 21. These

  different switches are provided on the board

  (21) and are connected to the microcomputer 17 via a

switch reading face 29.

  Figures 4a-4e schematize the method of pre-

  paration of the assembly of the machining buffers 21 for a datum of a particular machining phase, selected from the data recorded in the input buffers 20 by manipulating

  input data adjustment switch 25.

  Figure 4a shows the basic shape obtained during

  introduced into the input buffer 20, the data cor-

  corresponding to the shape of the machining at the starting point T at the point of arrival F and the radius R. After having introduced the data of the basic form into the input buffer 20, the data switch d is depressed. machining 28 then the CPU 18 calculates the center P of the arc of the circle, the top K of the arc and the point of contact d between the slope (tangent) and

  the bow (Figure 4b). Among the angles of cut / m, d m 'of the-

  Finishing tool m and roughing tool m ', one refers to the feedrate, the smallest of which is called d \ and the cutting exit angles 13 m, / 3 m' of finishing tool m and of

  the roughing tool m ', the smallest of which is called / 9.

  The points of intersection b and e are calculated from dk

  and d to find a form of machining that can be real-

  executed on the lathe using the tool made beforehand.

  lable. The radius of the spout is then trimmed along the radius rm of the finishing tool m (FIG. 4c) and the path a ', b', c ', d', K ', e', f ', P' the actual movement of the finishing tool m is calculated so that by machining one obtains the shape of Figure 4b. In addition, the radius of the arc changes from R to rm. Then prepare the finishing pad. As shown in FIG. 4d, the radius of the tip of the tool is compensated by the radius rm 'of the roughing tool-and a path a ", b", c ", d", K "is calculated. e ", f", P "of provisional movements of the roughing tool for machining, to arrive at the form calculated in FIG. 4b and the radius of the arc from R to rm 'is changed. In addition, the coarse machining points a "', b" ", c", ", K', and" Pu ", P" "are calculated with the finishing tolerance from the travel path of the machine. the tool

  roughing m 'to prepare the coarse finishing pad.

  Finally, as shown in FIG. 4e, the coarse machining points Gi, Hi, Ji are calculated giving the finishing allowance S starting from the coarse finishing points to prepare the coarse finishing pad. In addition, when this rough machining is done by reciprocating the roughing tool m 'is carried out n times as shown in Figure 4e, we do not search every time points Hi, Ji,

  Gi and they are not recorded in the coarse finishing pad.

  IESO; instead we only record Hi, Gi, Ji

  first time in the coarse finishing pad and then

  that the calculator passes on the next phase, it does the

  successive calculations according to the data of the pre-

  give and save the results in the final buffer.

  to update the contents of this buffer; In these circumstances, it is sufficient

  memory capacity to arrive at an infinite number of

  coarse machining tools. The operation described above is given in the list below. Machining Buffer Inlet Buffer (for each no machining buffer)

Buffer Buffer Stamp

  (for each finite case of Lusin-age-3, cross-fit for X (T) X (a ') X (a' ") X (Gi - 1) Z (T) Z (a ') ) Z (a '") X (Gi) X (A) x (b') X (b '") Z (Gi) z (A) Z (b') Z (b '") X (Hi) x (F) X (c ') X (c' ") Z (Hi) Z (F) Z (cM) (c (c '") X (Ji) RX (d') X (d ') Z ( J) z (d ') Z (d ") m X (K') X (K '") m' z (K ') Z (K' ") NX (e ') X (e"') v Z (e ') Z (e' ") x (f ') x (f' ') z (f') z (f '') x (P ') X (P' ') Z (P') z (P '") R-rm X (P" "))

Z (P ""))

  R-rm 'As soon as the calculator CPU 18 performs the calculations on the basis of the data recorded in the input buffer

  to complete the assembly 21, the turn is controlled "automatically

  tically by the data of the assembly 21 and the workpiece is machined to the predetermined shape. If only a minimum of data necessary for machining in the input buffer 20 is stored and the data is stored in the input buffer 20, then machining edf ec ei cza Te -ois Y Cpu 18 sula

  base of the data applied to the input buffer 20; the result

  The state of the calculations is recorded in the set 21. According to this installation, the indicated list shows that the content stored in the input buffer 20 is considerably reduced and as it suffices for a single machining buffer set 21, whatever the number of input buffers 20, one can record a large number of parts machining forms in

  microcomputer 17, at the same time.

  To increase the storage capacity of each input buffer 20 can be provided a CPU unit, separate for the detection of the job number, in addition to the CPU 18 to prepare the set 21 on the basis of data applied to the input buffer 20, the CPU unit which detects the part number being connected to the input buffer 20. If, when an instruction transfer of the CPU unit 18 is performed in the CPU number detection unit piece, the data stored in the input buffer 20 is transferred to the CPU 18. The memory can thus be increased in

  the limits of what is allowed for the CPU unit of de-

  part number, regardless of the capacity in

addresses of the CPU 18.

  The foregoing description shows that in the

  given above, the data needed to machine a part

  can register using a memory capacity, mini-

  male, which makes it possible to record at the same time in the micro-

  calculator, the data needed to machine a large number of parts. As a result, in a workshop producing small series, very diverse, when one wants to manufacture repeatedly, a limited number of parts, it is necessary

  to save the data concerning the parts in the micro-

  computer. By proceeding in this way it is possible to carry out

  swimming in a particular room by simply operating the

  com: utateurs to read the dornnes correspond to this piece.

  It is not necessary to re-record the data each time you change rooms, as necessary; this increases the renderent.

  Moreover, when you have to record in the micro-

  calculator the data corresponding to a particular part, it suffices to introduce a minimum of data, which facilitates

  considerably this introduction. Although the shape of the

  If the workpiece is complex enough to exceed the number of machining steps allowed by an input buffer, this problem is solved by entering the part number into several input buffers. In this way, it is possible to

  to treat a number n of machining phases, permitted by a tamper

  the number of input buffers N (i.e., n x N) by simply manipulating the coin change switch and the readiness switch.

machining stamp.

  A process for preparing the machining stamp 21 envisaged above will be described below by taking as an example a copying machine processing a complex shape having concave portions and convex portions as shown.

in Figure 5.

  As described above, each input buffer has a portion of memory for storing a set of cut data ex, g 'z. a set of machining tolerances Lx, Lz, a set of finishing tolerances S xe 6 z and a point of

  cut T regardless of the number of machining phases. (The suffi-

  xes x and z correspond to the components x and z). The finishing pad has a memory section for recording a machining shape, a start point A, an end point F, a center point P, a radius R and other elements (including speed

  of rotation and advance) for each machining phase.

  The coarse finishing pad has the same organization

than the finishing pad.

  The coarse finishing pad has a portion of memory to record a set of finishing tolerances

  coarse machining S'xi, & zi, a starting point for roughing

  A, a finishing point Fi and a central point of cut Pi, irrespective of the number

of machining phases.

  The input data described above relates to elements concerning the machining shape, the dimensions of

finish and the input buffer.

  The model of the machining form is divided into

14 2480961

  three parts namely a straight line, a convex arc and a concave arc. When the outline of the finishing shape of a part breaks down into a combination of straight lines, arcs

  convex and concave arc, the corresponding data are

  straight lines along the coordinates of the starting point and the end point and the coordinates of the starting and ending points as well as the radius of curvature of the arc

concave or convex.

  The coordinates are expressed by taking the right origin of the part, the Z axis corresponding to the axis of the part and the X axis being perpendicular to the previous axis. This process

  allows direct use of the finishing machining dimensions

tion of the piece.

  A practical example of input data from a

  machining shape model and finishing machining dimensions

  The contour will be divided as follows in FIG. 5. The contour is divided starting at the left end into a straight line, a convex arc and a concave arc, and the data for the various machining steps are entered as follows. hase M dl Point of 1 Point F of machining Jdpart I of arrival4ao Il Straight line A1 F1 2 Convex arc A2 F2 R 3 Straight lineA3 F3____ 4 Concave arc A4F 4 Straight line A 6Arc convex A6 F6 7 Convex arc A6 F6 R7 8 Arc Concave A 8 R 9 1 Straight line A9 F9 Starting from the entry point, the CPU 2 calculates the machining shape, start point, end point, center point, radius and other elements ( including the speed of rotation and the speed of advance) for each phase of machining; The results are saved in the finishing buffer. In

* function of such data, the CPU 2 unit decides whether to

  think the tip of the cutting tool and whether the machining paths of the adjacent machining phases are continuous or not; the resulting data is saved as a travel path for the finishing tool for finishing machining to ensure

continuous control of the machining.

  When the Dreoaration of the usinaae data of all the machining phases of the input buffer is completed,

  the next step is to prepare the data for the

swimming rough finish.

  Under these conditions, the path of movement of the coarse finishing machining tool is such that it is offset from the path of movement of the finishing machining tool by a distance corresponding to the finishing tolerance. We

  can thus have a shape by connecting an infinite number of rec-

  tangles defined by the X and Z coordinates of the position components as well as the finishing tolerances-6 x, z next

  the finishing line (see Figure 6).

  As the shape of the machining during each machining phase is the same as the shape of the finish, the way

  to find the coarse finishing dimension during each

  that machining phase will be described below. The way to find the coarse machining point is the same for each machining phase during a given machining operation (for example Nth machining phase) if the starting point of the finishing corresponds to AN, the point d arrival at FN, and the central point

  to PN and if the starting point of the coarse finish corresponds to

  corresponds to AN ', the point of arrival at FN' and the central point at PN '' the coarse finishing point is represented

  by the finishing point to which the final tolerance is added

  tion. We obtain: X (AN ') = X (AN) + x XNF') = 4 (FN) + x

X (PN) X (PN) + X

  Z (AN ') = Z (AN) + z Z (FN') = Z (FN) z Z (PN N = Z (PN) _ z In these relations, the plus or minus signal preceding Z is

16 2480961

  determined so that the sign is plus for X (AN) X (FN), and

  that the sign is less for the inequality X (AN)> X (FN).

  When the calculations are made according to the rule above, in the case of a shape such as that of Figure 7, with a starting point X (AN) for the Nth machining phase which is less than or equal to the point of arrival X (FN) and with a starting point X (AI) which for the previous machining phase

NEITHER NOR

  is greater than the point of arrival X (FN), there is a shift of the point of contact between these two machining phases. Point

  finish of the coarse finish eFN ') is given by the

  following mules: X (FN ') = X (FN) + x Z (FN') = Z (FN) + z but the starting point of the coarse finish (AN_1l) for the (Nl) machining phase is given by the following formulas:

X (AX (ANN) + ^ X

- N-- X

  Z (ANl ') = Z (AN-1) z Thus the points (FN') and (AN ') have the same

(N) (N ')

  coordinate X, but the ordinate Z is separated from 2 (AN1 = Fz, AN_1 = F Thus in the case:

X (AN) - X (FN)

  X (An_1)> X (Fn-1) the difference between the contact point during the two machining phases can be suppressed and we can arrive at a continuous command by interpolating along a line connecting (FN ') and (AN_ ') In addition, this difference at the point of contact occurs in the case of Figure 8. It is thus:

X (AN)> X (FN)

N N-

(AN_1) - X (FN-_)

  X (FN ') = X (FN) + ex) Z (FN') Z (FN) - X (AN-1 ') = X (AN-1) + x

Z (AN-1 ') = Z (AN-1) + Z.

  In this case, the points (FN ') and (AN_')

  range from 2 & z (* 'AN-1 = FN).

  q) Then, the intersection between the straight line (or arc) (A ')) (FN') and the arc (or straight line) (AN l ') - = - (FN' is calculated by the installation who makes up the bow using

  the intersection as a point of contact.

  This intersection can easily be calculated

  from the equation of the coarse finishing line corresponding to

  laying at the Nth machining phase and the equation of the line of

  coarse finish for the (N-1) iene machining phase.

  In the other cases than the two described above (FIGS. 7, 8) there is no such difference between the contact points so that compensation is not necessary. In summary, the flow chart for the calculations of the different points of the Nth coarse finishing machining is that shown in Figure 9; the same flow chart is used sequentially for all the machining steps and the results are stored in the coarse finishing buffer. In addition, in the flowchart of FIG. 9, for N = 1, it is indicated that

  the previous machining step (N - 1) does not exist and the results

  previous calculations are stored in the buffer of

coarse finish.

  Such quantities stored in the coarse finishing pad indicate the main points of the coarse finishing line for machining coarse finish and

  the moment of the machining of coarse, real inition, the interpolation

  Linear or curved interpolation are made between adjacent points, following the shape (straight or curved) to obtain

  continuous contour machining data.

  The preparation of the rough machining stamp will be

described below.

  In the case, the term "rough machining" or "roughing" concerns the machining of a rough blank, until one reaches the rough finishing line and the part

  cut or removed is usually called "tolerance".

  In this invention, the tolerance is defined as the curve obtained by connecting an infinite number of rectangles determined by L, L on the finishing line (as shown in Figure 10) the set encompassing the tolerance

  between the finishing line and the coarse finishing line.

  Cutting quantity and machining tolerance

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  & z. sz derive from the relation LX / Lz = Qx / = z = r x / Yz on the basis of tolerances entered initially L X Lz, of the degree of

  Yx cut and finish tolerance g.

  The dimension L of the X-axis tolerance x can be set according to the draft part of the maximum tolerance used as a standard. Even if there are some variations in the actual tolerance between the parts of the individual drafts or the same roughing compared to a set value, there is no

  difficult because it is only a rough machining.

  In particular because the tolerance is chosen according to the finishing line which is the shape or the final machining curve, this way of proceeding does not influence the precision

machining of the piece.

  As rough machining is performed by gradually cutting the blank from the outside and passing

  at the coarse finishing line, the quantity removed, the name

  The number of repetitions of coarse machining operations is such that if the tolerance is divided by the quantity removed or the quantity cut off, a quotient (integer) and a remainder are obtained; the rest is added to the cut quantity for the rough machining time. First, we will describe how to find

  each time the path of the tool for rough machining.

  This can be considered in the same way as to find the coarse finishing line from the finish line described above. Thus, the finishing point AN of the flowchart of FIG. 9 is taken as the coarse finishing point AN 'and the finishing tolerances s, iz as coarse finishing tolerances & Xi, SZ i However, coarse finishing tolerances are reduced a quantity corresponding to

  the quantity cut for each coarse machining.

  In practical terms, referring to the

  gram of FIG. 11, the path of the tool for the first rough machining is calculated according to the starting instruction

  machining. For this purpose, we subtract the finite tolerances

  6x, i input tolerances L, L, and then subtracted

  from the result the magnitudes for the cuts ex, Wz.

  The next step is to decide whether the quantities i, ', & zi are each equal to or less than 0. If both answers are yes, the reading ends; if both answers

19 2480961

  are nong for the machining phase N used corrse Rhase usi

  final swim n ', we take the starting points X (A), Z (A), the points of arrival X (Fi), Z (Fi), and the central points X (Pi), Z (Pi ) for rough machining from this nil machining phase. When the coarse machining start point (A.) and the coarse machining end point (Fi) are obtained for the nth machining step, the roughing tool (Ai) is moved to ( Fi). If the phase N is the phase l we go to the section (T) and if the machining phase N is different from 1, we advance the machining phase on the next machining phase namely N which is replaced by N-- 1; and we look for the starting point of roughing (Ai), the point of arrival of ridge (Fi) and the central point (Pi) for this phase

  machining, this operation being repeated until for N = 1.

  In rough machining (roughing) the coarse machining buffer has a memory capacity corresponding only to one machining phase, so that the tool is removed each time and re-entered in the memory for further processing.

machining.

  As soon as the first coarse machining is completed in this way, the second coarse machining is started. At this point, we have the coarse finishing tolerances <xig 6zi by removing the cut quantities V xyz We repeat the machining> folder until the coarse finishing tolerances -mi Zi are such that _O and É0 xi t & zi In practice, according to FIG. 5, the path of movement of the tool for the upper line is machined starting at the right while searching for the points of departure.

  end and center, until the tool reaches the end

  Then, the tool returns to the cutting point T and finally the second rough machining is performed in the same manner. Finally, the quantity corresponding to the remainder of the division of the cutting quantities Vz is cut off by the coarse finishing machining until the coarse finishing line is reached and the quantity corresponding to the tolerance of finishing by doing the finishing machining for

finish the job.

  In the method described above, copy machining of a complex shape having concave and convex portions on a numerically controlled machine tool can be performed by simply introducing into the machine the dimension of

  finishing machining since the calculator then calculates

  the coarse finishing dimension and the roughing dimension. This reduces the number of manual entries that the operator must make and the unnecessary movement

  of the tool, which results in a very efficient machining.

  The way to prepare the assembly 21 of the machining buffers will be described using a rough machining example

  of a cylindrical piece on a lathe.

  As described above according to the invention, it is possible

  automatically machine a piece to give it a com-

  such as that shown in FIG. 12, by rough machining, then rough finishing machining and

  finally to a finishing machining; for that, we introduce simple-

  the common data including the original position (for attaching a tool), the finishing tolerance S and the cutting angle C as well as the rear angle of cut P and the radius of the point r associated with a predetermined number of the tool as well as the data of the machining phase such as the shape of the machining, the X and Z coordinates of the cutting point, the X and Z coordinates of the starting point, the X and Z coordinates of the point the radius of cut of a corner (leave) R and the cut quantity Y, the number m of the finishing tool, the number

  m 'of the roughing tool, the speed-of rotation N, and-

  the speed of advance V. The assembly 21 comprises a finishing pad, a coarse finishing pad and a machining pad

  coarse or roughing, to record data relating to

  the size of the finished machining, the size of the coarse finishing machining and the coarse or rough machining. The coarse machining stamp is provided in such a way that data relating to the machining form, the starting point A, the ending point F, the center point P, the radius R, the cutting quantity (, the starting point of roughing M and other parameters (including the speed of rotation and the speed of advance) for each machining phase

  as shown below.

  Coarse machining buffer User phase 2nd 2nd machining form concave pass convex circle Starting point

X (A), Z (A) (100, 200)

Arrival point

X (F), Z (F) (150, 200)

Central point

X (P), Z (P) (100, 250)

Radius R 50

  - - - - - - - - - - - - - - - - - - - - - --- - - - -

  Cutting size 5 Starting point M roughing Other parameters The finishing buffer is made of the same

  way that the roughing buffer.

  The coordinates of the starting point, etc., are expressed using the rectangular coordinate system, the origin being at one end of a blank the axis of rotation of the outline constituting the Z axis and the X axis being perpendicular Z-axis. The magnitudes of starting point, end point, center point, finishing buffer and finishing pad

  coarse, are calculated and stored according to the size

  The number of the machining phases described above is given in FIG. 12. The first machining phase is between points 1 and 2, the second phase between the two machining phases described in FIG. points 2 and 3 etc; the final machining phase is between points 9 and 10. According to FIG. 12, the operation is divided into 9 machining phases; the starting point of each machining phase is calculated and in the case of a machining form and an arc

22 2480961

  for each part of the blank, the center point is calculated

and it is recorded in the buffer.

  The roughing buffer registers the one-part roughing point Gi-1, the roughing point Gi, the finishing point Hi and the roughing point Ji as is indicated below. Thus using such a buffer, there is a memory capacity, sufficient to record data preceding a machining phase that is to say four points, which

  regardless of the number of machining phases.

  Trimming buffer Trimming starting point of a previous unit X (Gi-1) Trimming starting point X (Gi), Z (Gi) Trimming end point X (Hi), Z (Hi) Point of roughing back X (Ji), Z (Ji) The coarse or rough machining can be classified according to the two forms of machining, namely an open form like that of FIG. 13 or a concave shape to a

  only one passes as shown in Figure 14.

  In addition, the schema of the instructions for moving

  of the tool in coarse machining (roughing) is set as shown in Fig. 15 so that the path from Gi-1 to Gi allows fast forwarding for the open form and a cutting speed for the unidirectional concave shape ; for the path between points Gi and Hi, the cutting speed is used for both types; for the path between the points

  Hi and Ji, we use fast return for both types.

  If one calculates successively the coordinates

  Z and X of Gi, Hi and Ji, one can obtain a rough machining.

  The calculation process will be described below: The following relation must be obtained:

  X (Gi) = X (Gi-1) - (t cut size).

X (Hi) = X (Gi)

  X (Ji) = X (Gi) + a (fixed value, given 0.1-0.5 mm).

Z (Ji) = Z (Gi).

  Therefore, the only difficulty is Z (Gi) and Z (Hi) which can be found in the following way depending on the shape to be machined, Form to be machined Z (Gi) Form open Z (Gi) = Z (A _) + b (b = 0.1-5nm) Concave form Z (Gi = Z (A) - S a pass Z (Gi) X (A) - X ()

  --- - - - --- - - - - --- - - - ---- XA-X () X - -Gi--

  Convex circle Z (Gi) = Z (P) -R2-X (P) -G) 3 - 6 a pass (P) -X (Gi .... Concave circle Z (Gi) = Z (p) + 1R2 - X (P) -X (Gi) 3 - 2 a pass In these formulas A is the starting point of n

  the final machining phase (right end).

  Machining form Z (Hi) Conical Z (Hi) = Z (A) - XZ (A) Z (F) X (A) X (Gi) 3 +

X (A) -X (F)

  Convex Circle Z (Hi) = Z (P) + R2 '2 X (P) -X (Gi) 3 2 + Concave Circle Z (Hi) Z (P) RP) -X (Gi 2 + Thus, we can find Z (Gi) of a concave cone with a single pass, from the coordinates Z and X of the point

  taper (A) and end point (F) for the final

  Coarse - (figure 16) taking into account the finishing tolerance 6. The reason for taking into account this finishing tolerance 6 is that the tool must not be cut in the finishing machining path coarse during roughing, to smooth finish resulting from coarse finishing machining although this is not absolutely necessary. In addition, Z (Hi) of the single pass concave part can be calculated in the same way as above

Figure 17.

  In addition, as for Z (Gi) of the convex circle, the Z and X co-ordinates Z (P) and X (P) of the central point can be calculated from the starting point of the arc and the point of arrival. of it and the radius R, the calculation being done

as shown in Figure 18.

  Similarly, we calculate Z (Hi) for the concave circle

  as shown in Figure 19.

  We calculate Z (Gi) of a convex circle com = e this is represented in figure 20 and Z (Hi) as it is represented

in Figure 21.

  Therefore, for a given machining form, with a start point A, an end point F, a central point

  arc P, an arc radius R, a cutting quantity Y, a tolerance of

  6 and the X coordinate (Gi-1) of the roughing-off point which precedes one unit, it is possible

to calculate Z (Gi) and Z (Hi).

  As for A, F, P, R, and g, it suffices to give the number of the machining phase N to the finishing finishing buffer. So after all, just give the number of the machining phase N for the coarse finishing pad and

X (G-l).

  The number N of the machining phase for Z (Gi) or Z (Hi) can be given sequentially and the number of the phase

  machining for others is chosen.

  Figure 22 shows such a flow chart.

  The starting point of the roughing X (M) for all the machining phases of the coarse finishing pad of FIG. 22 can be canceled in advance as for the starting point of roughing (Gi-1) which precedes a unit; this can be done at one time, just give the end point (F1) of the first machining phase for the buffer of

  coarse finish. This is why X (Gi-1) = X (F1).

  - As for the phase number of Cisinage N, the

  roughing begins at the final machining stage N = n.

  The quantities X (Gi), Z (Gi), X (Gi),

X (Ji) and Z (Hi).

  Then, we give the machining phase number which

  preceded by a unit N '= n - 1 and Z (Ni) is calculated.

  In this case, if the two coordinates of X for the starting point X (AN ') and for the ending point X (FN') of the Nth machining phase, are less than X (Gi) ^ we have the number of the machining phase which precedes one unit and this machining phase number which will give X (A) or X (F) greater than X (Gi)

is chosen for the calculation of Z (Hi).

  If the number (N'-1) of the machining phase, which precedes this machining phase by one unit, does not include an X (MN) roughing point, then X (MNl) = X (Gi-1) in the coarse finishing buffer. (X (M)

  for all the machining phases is cleared in advance).

  The following decision concerns the end of the sidings

  wise; if the roughing is finished, the machining proceeds to the next phase number N-1 and the value X (MN) is recorded

as corresponding to X (G-1).

  If the operation is not complete, an instruction

  is sent to move the tool Gi-ns Hi.;> Ji, but by comparison

  reason with the cases represented in figures 23 and 24, it is necessary that after the displacement on X (Gi-1) + a in the direction of the axis X, one passes to Z (Gi) + X + a tg ( t-3)

  in the direction of the Z axis, for the first time.

  This means that in the case of FIG. 23, the number of machining phases for the coarse machining buffer is equal to 4; the first machining phase with Al starting point and as end point F1, we move to the second machining phase with starting point A2 and end point F2, then to the third phase of machining. machining as starting point A3 and as finishing point F3, then at the fourth machining stage with starting point A4 and end point F4. We begin roughing at the final machining phase or fourth phase. In this case, Gi, Hi, Ji is calculated according to the process shown in Figures 16 and 17; G2 is deduced from G1 according to the method of Figure 16; H2 is found from the process of Figure 19 etc. In the case of Figure 23, the starting point of the roughing, the end point and the return point for the third machining phase are suffixed "i", which gives Gi, Hi, Ji; these points can be calculated by the method already described. However, the starting point of roughing X (Gi-1) of the machining phase which precedes a unit that of Gi was the starting point of roughing X (NN.

  in practice X (Gi) of FIG. 23 corresponds to X (Gi-1).

  According to Fig. 23, an instruction is used to move the tool to X (Gi-1) + a, that is X (Gl) + a in the direction of the X axis, and then to Z (Gi) + X (Gi-1) -X (Gi) + a in the direction of the Z axis. Tg (δ -3) The magnitude ((Figure 3) is the cutting exit angle of the tool and is introduced as input, in advance

in the control device.

  When calculating the roughing start point Ji, the finishing point Hi and the roughing point Ji for the roughing phase from the starting point sizes and the finishing points of the various phases of machining recorded in the coarse finishing buffer, the instruction is issued only if Gi, Hi, Ji can be calculated for the first moment of each phase

  machining for coarse finishing pad.

  In the case of Fig. 24, the coarse finishing pad registers A1 and F1 respectively as the starting point and the end point for the first machining phase; A2, F2 are respectively recorded as starting point and as finishing point for the second machining phase and A3, F3 are respectively recorded as starting point and as finishing point of the third machining phase. Under these conditions, the number of machining phase is equal to 3. The first point X (Gi-1) of the third machining phase is given by X (Gi-1) = X (Fi) of the flow chart. of Figure 22 and the point GI for n = 3 follows from the process shown in Figure 16. Hi is obtained according to Figure 17 and (Ji) is obtained as follows J (1) = X (Gl) + a and Z (J1) = Z (Gl). G2 is found from the start point A2 and the end point F2 of the second machining step according to the method of FIG. 16; H2 is found according to the method of FIG. 17. Under these conditions, as for the movement of the tool for the point X (Gi-1), namely X (G-2) moves the tool from the point Ji to the X (Gi-l) + a in the direction of the X axis. However, in fact X (Gi-1) is X (ti) and X (Gl) + a corresponds to X (Ji). So for the transition from Ji to X-02- 1), there is no movement in the direction of the X axis (because this movement is not necessary) and the tool moves only in the direction from the Z axis to Z (G2) + tg {(G240a, namely Z (G21).) In the case of the point

  G3, as this is the second moment of the second phase of

  swimming (and that there is no such movement) the tool goes directly

from point J2 to G3.

  When the roughing is completed in the manner described in Fig. 6 -> Hi ---> Ji, X (Gi) is transferred to X (Gi-1) in the roughing buffer and the recording of Gi, Hi is deleted.

  and Ji in the roughing buffer.

  The value X (Gi-1) is given and the roughing

  is done during the calculation of Gi, Hi and Ji next.

  As the content of the roughing buffer is progressively updated as just indicated, it is possible to have a memory of very low capacity and which

  can receive an unlimited number of times of roughing.

  In addition, in the case of an open form, as we have Z (Gi) = Z (An) + b (with b = 0.1-5mm, and An as the starting point of the last machining phase ), it is enough only

to calculate Z (Hi).

  The number of the machining phase can be obtained in the case sequentially from the first phase

machining.

  As shown in Figure 5, the flowchart

  to the calculations is very simple in the case by comparison

  with the concave single-pass curve described above.

  The combination of the two types, that is to say of a single pass concave part and of an open part in the case of roughing processes, makes it possible to machine

very complex shapes.

  In addition, according to the invention, a form of machining given by the points A, B, C, D, K, E, F, (Figure 26) can be rough in a single operation. If the installation is such that one can record X (M ') to be used separately from X (M) within a machining phase, one can make the calculations in a machining phase in using a flow chart

  wherein X (M) of Figure 22 is replaced by X (M ').

  With this, it is possible to machine complex shapes having concave and convex parts and this by a simple input operation, which greatly improves

  the possibilities of numerically controlled towers of this type.

  The description below relates to a method permitting

  finding a machining form that can actually be

28 2480961

  machined using the lathe using a tool of predetermined shape.

  For example, to cut the vertical wall portion 30a of a workpiece 30 (Fig. 27) with a cutting tool 40 whose cutting angle r; is equal to or less than 900, if the tool 40 moves from right to left, depending on the final dimension of the part 30, the tool 40 meets with

  difficulties in removing the vertical wall 30a.

  Moreover, in the case of a part 30 having a concave part 30b (FIG. 28), to cut the vertical wall 30c at the initial end, the cutting tool 40 whose end angle of cut P is smaller or equal to 90 meets difficulties.

  To overcome these difficulties, a process consists of

  it would be for the operator to compensate the input quantities around the definitive dimension of the part taking into account the shape of the cutting tool used, by introducing this shape; another method would be to cut to the entry point 0 at a fixed angle e, regardless of the shape of the

  the tool and the final shape of the piece (Figure 29). Toute-

  However, there is a great diversity of shapes of sibian cutting tools that the first method of offsetting the input quantities leads to very complex input operations and may cause errors; the second cutting method according to a fixed pattern has limits according to

the final shape of the piece.

  The present invention consists of classifying the various tools used on the towers, according to their shape, using code numbers, to record them in a fixed manner in the memory section of the numerically controlled lathe, to introduce the data of the tools to be used. in a machining data preparation section with a code number and retrieving the recorded data corresponding to a particular tool. The classification of the tools according to the form is based on the cutting angle 9 and the cutting exit angle (p of each tool (Figure 3), these quantities are classified according to code numbers as shown in the table below:

Board

  used keyboard input. Code O

o- - - - -

1,930 50

2,450,450

3,600,600

4 750 150

930 370

6,930,520

7 930 93 0

  It is desirable that the digit numbers in the code numbers are small. The method consists in using the functional keys of the invention, described above, introducing the shapes to be machined and cutting quantities, in digital representation and as indicated by the final dimension provided on the plans; the introduction is done in the section

  to prepare the machining data using the function keys

  of the control panel keypad.

  The machining data preparation section automatically calculates the optimum path of the tool, from the entered tool code number, the machining pattern diagram, and the cutting size to prepare the data.

machining.

  Machining shapes are classified into: straight line, inclined line, convex circle, concave circle, concave circle

  a single pass, etc., and the corresponding function keys

  are provided on the control panel so that the operation

  The controller can order them to introduce the diagram. Furthermore,

  each key is identified by one or more corresponding words.

  Schemes are characteristic of any form

* Machining and can apply to any complex shape.

  As for the cutting size, the axial dimension of the part as well as its radius, and the end surface

  of the reference document, are introduced in

digitalisation.

  In practice, we take for the axis Z, the axis of the

  part and for the X axis, an axis included in the end surface

  the room; the starting point and the end point for the machining position are measured from the end surface of the workpiece; the quantities measured represent coordinates along the X axis and the magnitudes of the radius

  definitive at the point of departure and the point of arrival of the posi-

  Machining are Z-axis coordinates. For example, as shown in FIG. 30, when machining a concave curve, following a pass, the key of a single-pass concave curve is used to introduce the shape to be machined; the dimension or axial length k separating the end surface S from the machining starting point A and the radius r at the point A are introduced as input signals as well as the cutting quantity, the axial length m of the surface. end S of the workpiece to the machining end point F and the radius r at the point F and the radius t in the cavity between A and F. As a result, the machining data preparation section record the form to be machined as follows: X coordinate of point A is X r, and its coordinate Z is Zk X coordinate of point B is Xt, and its coordinate Z is -Zk X coordinate of point C is X t, and its coordinate Z is -Zm X coordinate of the point F is Xr, and its coordinate Z is -Zm The machining data preparation section thus calculates the optimum path of the tool according to the form to

  machine and the code number of the tool.

  In this calculation, the ABC comparison is made with the cut exit angle f of the tool as well as t-4BCF which is compared with the angle c of the tool. If Y -t ABC and t - 4BCF are less than (and c, it is decided that there is no need to compensate and the tool path data is prepared with machining data such as A -4 B - 4 c F. Thus, for t - t ABC and t (- 4 BcF equal to r which is greater than P and i, we compensate the points B and C as follows: L AB'B = e - 3 = (3 L BC'F = c4 - 3 = d0 1 The angle of 3 gives room to avoid interference with the tool and this angle can be a minimum irreducible, not limited to 3 o

  The coordinate C of point B 'is the same and only

  its coordinate Z is compensated in the following way -K - (r -) cot P 'Moreover, the X coordinate of point C' is the same and only the Z coordinate is compensated as follows -m + (r - t) cot ck'o Thus, if't <ABC <y it is not compensated if - <ABC (is compensated if t - BCF 4th, is not compensated

if - <BCF -) is compensated.

  If there is compensation, the path of the tool is the following

A-- B '-> C'- F.

  The same procedure is performed if, as shown

  in FIG. 31, there is a conical or inclined portion

  a concave single-pass curve and if, as

  in figure 32, there is a convex circle inside

  from the concave part to a single pass.

  According to FIG. 31, the path of the machining form is introduced by means of the keys serving for a concave part with a single pass and an inclined part; the cutting quantity is introduced by introducing the information A (XA, ZA),

  B (XB, ZB), C (Xc, ZC), D (XD ZD) and F (XF, ZF).

  By proceeding in this way, the comparison described above for B, C and C is made. In the case of FIG. 31, the points B and D are compared and the angle at point C is

  less than k, no compensation is made.

  Point B is compensated for its Z coordinate, of

  way to move this point to point B '.

  The Z coordinate of point B 'is calculated as

follows ZB - (XA - XB) cot / '.

  We compensate for the point D to move it to the point D 'and its X coordinate is: XD (ZF ZC) tg o' + XF (XD - XX) XD - XC + (ZD - ZC) tgcQ The Z coordinate is the next:

32 248096,

  ZC (XD - XF) + ZF (XF - Xc) + (ZF - ZC) ZF XD Xc + (ZF ZC) In addition, in Figure 32, the machining diagram is introduced by the keys of a concave curve to a single

  passes and a convex circle; the cutting quantity is inserted

  picking the data A (XA / Z) r B (X, Z), C (Xc, ZC),

A XB ZB C C

  D (XDr ZD), F (XF, ZF) and the radius R of the arc.

  In the case, we compensate in the same way the point B to pass it to the point B 'and we compensate the

points C and D as follows.

  We first compare the angle of the tangent to the circle at point C to the cutting angle i of the tool as described above and if this angle is equal to or greater than J, we

  compensate for the point to move it to C '.

  As for the point C ', we find the tangent of the arc of angle i' and the intersection between this tangent and the line segment BC so as to automatically calculate the

coordinates of point C '.

  As for the point D, one finds the intersection D 'between a line of angle G3 passing by the point F and the arc, like point of compensation and one calculates the coordinates of this point. This is why, according to FIG. 32, the path of the tool A -> B '- is obtained. C - => Of l - F which constitutes the data of machining. In the case of a concave circle, we make the

  same way a comparison and a compensation.

  As described above, one can automatically correct

  tically the machining shapes according to the tools that have

  different cutting angles and machining is performed.

  In addition, the invention makes it possible to decide whether the shape of the cutting edge provided by the input code of the tool makes it possible to cut a form of machining, introduced into the machine, if this cutting is impossible. operator is informed by

  the control device of the machining preparation section.

  This operation will be described more

detailed below.

  For example, as shown in Figure 33, for

33 2480961

  to cut an angle-inclined shape U and Et at conditions 4 t t and (t t, the circuit informs that the selection of

the tool is not correct.

  By machining a convex circle like the one

  34, similar information is given if the angle of the tangent at the initial end is greater than

  Where the angle of the tangent at the end of arrival is greater than

  laughing at p. For machining a concave circle as shown in Fig. 35, similar information is provided if the tangent at the leading end is greater than and if the tangent at the end is greater than ac.

  The above decisions are made by the provision

  control of the data preparation section

  machining according to the flow chart of Figure 36.

  When an instruction to find a toolpath is issued at the end of the input of the tool code number and the form to be machined, the decision begins and is

made for each form to be machined.

  Firstly in the case of the inclined part of FIG. 33, if the coordinates of the points A, B, C and D are the following ones A (XAD ZA), B (XB, ZB), C (Xci Z) and D (ZD) and if the gradient of ago- of the line segment AB is equal to tgar = (X - X) / - (z - Z), and only if this angle is equal

A B B A

  or greater than tg (3, we have an error representation;

  otherwise, the circuit decides that there is no error. The grading

  if tg% of the line segment CD is tg x = (XD - Xc) / 7 (ZD - ZC) and only if this gradient is equal to or greater than tgd & ', it is decided that there is an error; otherwise, the circuit decides

that there is no mistake.

  In addition, the above description concerns the cases

  line segment gradients that are taken into account.

  However, if this is not taken into account, the error can be displayed by deciding whether the cutting angle O and the cutting output angle (interfere with each other as shown by

the flowchart in Figure 37.

  Indeed, in the case of machining a workpiece having portions inclined in two places such as the

  line segments AB and CD in Figure 33, we examine separately

  the inclined parts. The gradient tg a- of the part

34 2480961

  the slope corresponding to the line segment AB is given by tgO = (XA XB) / (ZA - ZB) Only if tg cr tg 3 'and - tg 0- = tgc', the circuit decides that there is an error; in case

  otherwise, he decides that there is no mistake.

  The gradient tg of the inclined part corresponding to the segment CD is equal to tg = (Xc-XD) / (ZC - ZD) 'Only in this case, if tg (tg and si - tg = tg,', the circuit decides that there is an error, if not, he decides

that there is no mistake.

  In the case of a convex circle (Figure 34), if the coordinates of the points A and B are given by A (XA, ZA) and B (XB, ZB) and if the radius of the arc is equal to R, the gradient tg L 'of the tangent at the point A is equal to tgl' = - (ZR-ZA) / (XA-XR)

R A A R

  and only if tgt 'is greater than tgj, the circuit decides that there is an error; if not, he decides that there is no mistake. The gradient tgO- 'of the tangent at point B is

  equal to tg- '= - (ZB-ZR) / (XB-XR); only if tg r 'is greater than

  the circuit decides that there is an error;

  otherwise, the circuit decides that there is no error.

  In the circuit of a concave circle (Figure 35), if the coordinates of the points A and B are A (XA, ZA) and B (XB, ZB) and if the radius of the arc is equal to R, the gradient tg2A "from the tangent to the point A is equal to tgt" = - (ZR RA) / (X - XR); only if tgl "is greater than tg (', the circuit decides that there is an error and if it does not, it decides that there is no error The gradient tgC-" of the tangent at point B is equal at tgO- "= (ZB-ZR) / (XB-XR) and only if tgCr" is greater than tg ', the circuit decides that there is an error, if not,

he decides that there is no mistake.

  If XR and ZR are the coordinates of the center of the arc and are calculated automatically by the control device of the machining data preparation section, the calculated values are given by the following formula: XR = {a + d ( a - b) +. q / (d2 + 1) (In this formula the double sign means that there is the sign (-) for a convex circle and the sign (+) for a concave circle.

2480961

  ZR d-XR + a q = ta d (a - b) 3 2 (d2 + 1) (2a2 + b2 C2 - 2ab) a = X -ZX

A B

  c = R (convex or concave radius of curvature of a circle, input quantity) d = (XA-XB) / (ZB-ZA) As described above, according to the invention, it suffices that the operation introduce the code number of the tool

  to use as well as the size of the machining; then, the

  Positive control automatically corrects the shape of the

  swimming that suits the tool. Moreover, we can detect

  data entry errors, which reduces the work of the

  and allows high precision numerical control machining

if we.

  The compensation method of the moving path

  of the tool according to the radius of the tip of the tool will be

described below.

  In general to machine a piece for example of

  cylindrical shape and give it a shape such as that

  felt in Figure 38 using a lathe whose motion

  is controlled numerically, the operator introduces generally

  Then, the X and Z coordinates of the cutting point T, the start point A and the arrival point F in the control device comprising a microcomputer 170. Then, the microcomputer described above calculates the path of movement of the tool.

  for roughing, coarse finishing machining and machining

  Finishing swim, based on lap data and controls based on the results of the calculations. For example in the case of finishing machining, the circuit calculates the coordinates of the points a and f from the data and commands of the finishing tool so that the cutting edge of the tool is

  moves on the line passing through the points a, A. Fe f.

  In this context, it should be noted that the cutting edge of the lathe tool does not present a vertex to argue

  but this tool is rounded as shown in Figure 39.

  To adjust the movement of movement of the tool m according to the method described above, it is necessary to choose a certain point of

  the cutting edge as a set point. For this, generally-

  according to Figure 39, the fictitious cutting edge W is determined

36 2480961

  for each tool based on the radius r of the tip and is adjusted so that this dummy edge moves on the line connecting the points a, A, Fl f which are calculated by the microcomputer. Controlling the movement of the tool m by using such an imaginary cutting edge W presents no difficulty for the areas between the points a and A and between the points F and f. However, in the region between points A and F, on the inclined surface (or conical) the actual cutting edge of the tool m moves along a dotted line (Figure 40) and does not cut the hatched portion. Thus, according to the known solutions (FIG. 41), a method of correcting the radius of the tip of the tool is used; according to this method, the c-ad path described by the imaginary cutting edge W is calculated as the actual cutting edge moves between points A and F on the inclined surface; this calculation is done from the X coordinates of the cutting point T, the starting point A and the end point F as well as the radius r of the tip of the tool to adjust the fictitious cutting edge W of the tool m to move it along a path through points a, c, d and f, and properly machine the inclined surface. The coordinates X and Z of the points c and d are calculated in the following way:

  If the X and Z coordinates of point A are

  the X and Z coordinates of the point F being equal to X (F) and Z (F) respectively, the X and Z coordinates of the point T are respectively equal to X (T) and Z (T) and if the radius

  the tip of the tool is equal to r, we have the following relationships

  vantes: X (a) = X (A) Z (a) = Z (T) X (c) = X (A) X (c) = X (A) r {Z (A) -Z (F) + X (F) X (A) - (Z (A) -Z (F)) 2-F) -X (A)) 2}

Z (c) = Z (A) -

X (F) - X (A)

  ## EQU1 ##

X (d) = X (F) - -

Z (A) - Z (F)

Z (d) = Z (F) X (f) = X (T)

Z (f) = Z (F).

  Moreover, to machine a shape in which the inclined surfaces meet as in FIG.

  facilitate the description of two adjacent machining phases,

  one on the left side relative to the axis of the part is called the first machining phase and the other second machining phase) the path a - dl - f1 of the cutting edge is determined

  imagination using the same method as described above.

  above, using the data entered into the machine namely the X and Z coordinates of the cutting point T1, the starting point A and the ending point F and the radius r of

1 1

  the tool. The path a2 - - c2 - f2 'of the dummy cutting edge can be determined using the same method as described.

  above, using the input data, namely the coordinates

  X and Z of the T2 cutting point, the starting point A2 and the

  arrival point F2 and the radius r of the tip of the tool.

  The intersection Y between the extension of the line segment a '_ d and the line segment c2-f' is then determined from the data of the two paths; then after deleting the previously determined starting point a1 'of the first machining phase and the finishing point f 2' of the second machining phase, the point Y is fixed as the new starting point a1 of the first phase machining and the end point f2 of the second machining phase. This moves the fictitious cutting edge of the tool m along the path passing through the points

  a2, c2, f2, a1, d1 and fl for machining the workpiece to the desired shape.

  However, if the tool m. of the first machining phase and the tool m2 of the second machining phase are not the same tools and if the rays, r2 of the tip are different from each other, and if the oni wants machining a portion having inclined surfaces that meet, the implementation of the method to obtain the cherin of displacement of the fictitious cutting slab would result that comre shown in Figure 43, the tool m2 would not move until the end point corresponding to the second machining phase but leave uncut the hatched part inside the machining contour,

  overflowing with respect to this hatched portion.

  Therefore, the present invention uses the following method to determine the path of travel of the dummy cutting edge, which path is necessary to cut during the second machining step using two types.

  tool having different tip radii.

  It is assumed that the tool m2 of the second machining phase is used for the first and second phases as shown in FIGS. 45 and 48. It is further assumed that the radius r of the tip of the tool is equal Thus, according to the known methods, the paths of displacement a2-c2-f2 'and a'8-dl-f of the fictitious cutting edge of the tool m 2 are determined, which paths are necessary to cut at using the m2 tool in the first and second machining phases; the displacement path a '_ dl f is recorded in a temporary memory buffer of the microcomputer and the path of movement a2-c2-f2' in the normal buffer of the microcomputer. The shape (straight line, curve or incline) to be cut during each machining phase is determined using the data entered in the microcomputer, then we decide whether to find the intersection between the path of displacement of the fictitious cutting slab during the first machining step and the cutting edge moving path for the second machining step. If necessary, the intersection Y between the extension of the line segment a1'-d and the line segment c 2 ---- f 'on the basis of the data recorded in the provisional buffer and the normal buffer is determined. the data of the end point f 2 'for the second machining phase, in the normal buffer, are deleted; point Y is recorded as new point f2 for the second

machining phase.

  Then, as shown in FIG. 46, it is assumed that the tool m1 of the first machining tool is used for

  first and second machining phases and we take r = r1.

  The paths of displacement a2-c2-f2 'and a1'-d1-f1 of

  the fictitious cutting edge of the tool ml, necessary for the machining

  of the m1 tool in the first and second phases of

  are determined by the same process as in the example

  known as described above; after deleting the contents of the drum

  In the provisional view of the microcomputer, the path of movement a2-c2-f2 'in the temporary buffer is determined while the path of travel a -dl f is recorded in the normal buffer. The shape to be machined for each phase is determined

  machining using the data entered into the micro-

  calculator and it is decided whether it is necessary to find

  section between the path of movement of the cutting edge

  fictitious of the first phase of machining and the path of

  If necessary, the intersection Y between the extension of the line segment a1 '- d1 and the line segment c2 f2' is determined by using the values of the fictitious cutting edge of the second machining phase. data stored in the temporary buffer and the data stored in the normal buffer; after erasing the data from the start point a1 'of the first machining phase in the normal buffer, the point Y is recorded as the new start point a of the first machining phase. In this way, the registration of the path of displacement of the effective cutting edge of the first machining phase and the path of displacement at 2 cZ_ f2 of the dummy cutting edge of the second phase are completed. as shown in FIG. 47. It is then sufficient to control the turn so that the dummy cutting edge of the second tool mn2 moves along the path a2 C2 f2 and that the cutting edge of the first tool m1 moves along the white path to perform precise machining with two tools with different peak radii in two phases

consecutive machining.

  In addition, in the foregoing description, the tool

  has been described as moving from right to left in each machining phase, that is, the starting point of each machining phase is on the right and the point

  arrival is on the left; in the case of a tool moves

  from left to right, the starting point is

  as the point of arrival and the point of arrival as a point

departure.

  Moreover, in the case of the combination of an arc and an inclined curve or two arcs to be machined during two consecutive machining phases by means of two tools having different peak radii (FIG. and 50), the travel path alof1 of the cutting edge is determined.

  fictitious of the first phase of machining and the path of

  a2tJf2 of the fictitious cutoff of the second machining phase using the same process as that described above

  to precisely machine the workpiece to a given shape.

2480961

Claims (1)

R E V E N D I C A T I 0 N   A method of controlling a numerically controlled machine tool   a method in which all control data is required.   the preparation of the machining data is introduced into a control device by means of keys on a keyboard of the control panel, characterized in that the model of the form to be machined is divided into forms of open type and concave single pass shapes, each type further divided into a straight line, an inclined line (c8ne),   a convex circle and a concave circle, the data being introduced   in the control device, the instruction patterns   of the control device for moving the tool being fixed together   repetition for the quick-return movement of the tool par-   both of the cutting direction by the feed direction to the feed start point, the machining form being fed into the control device in the form of a pattern or a combination of patterns, common data and the data of the machining phases necessary for the machining, and the   Cutting paths for roughing are calculated successively   internally from the data obtained, according to the processes corresponding respectively to the shapes to be machined, for perform the machining.