METHOD FOR CONTROLLING THE MACHINING OF WORKPIECES

Description

[0001] The present invention relates to a method for controlling the machining of parts on a production line, enabling the identification and correction of dimensioning errors of said parts during the operation of the production line.

[0002] Production lines can include multiple machining centers that manufacture several parts. During manufacturing, tolerances are applied so that the parts vary in size around a nominal value, between a minimum and maximum value, while still fulfilling their intended function. Therefore, dimensional checks are routinely performed on the production line, allowing for corrective actions to be taken on machining centers that produce parts with dimensions deemed defective.To determine and apply these corrections, it is known that a production line operator randomly measures one of the parts on the production line, then compares the measured values ​​to the nominal values ​​of that part and manually applies corrections to the machining center when the measured values ​​deviate from the nominal values. It is also known to use a measuring machine that automatically measures one of the parts on the production line and then determines the corrections to be applied to the machining center, which are then manually implemented by the operator. Document EP 1 894 068 B1 describes a known method for inspecting the machining of a part by a machining center, the method employing a machine for measuring and inspecting a part.Documents DE 10 2015 012795 A1, EP 3 242 179 A1 and EP 0 478 290 A2 also each illustrate a known method for controlling the machining of a machined part.

[0003] One of the problems with such a machining control process is that, firstly, operator intervention can lead to human error in determining or applying corrective actions, and secondly, it requires significant implementation time. Furthermore, if the production line includes at least two machining centers configured to machine the same part—that is, a part with the same dimensions—errors in applying corrective actions to the correct machine, or errors in calculating and / or entering the corrective actions by the operator, can interfere with the production line's efficiency.

[0004] The invention aims to address the problems mentioned above by providing a method for controlling the machining of parts that ensures, firstly, a reliable determination of at least one corrective action to be taken on the parts machined on the production line, and secondly, that said corrective action is applied to the correct machine on the production line, i.e., the machine whose measured part requires corrective action. The invention therefore relates to a method for controlling the machining of at least one first part machined by a first machine and a second part machined by a second machine, in accordance with the characteristics of claim 1.

[0005] The process is then advantageous because it allows the need for at least one corrective action to be taken on at least one of the first machining machine and / or the second machining machine, in an automated and secure manner, using the measuring and / or control machine, during the operation of the production line.

[0006] Furthermore, the control process ensures that the correct correction is received by the correct machining center whose next machined parts require the correction; that is, the machining center from which the first or second part measured in the second step originated. This ensures the smooth operation of the production line in a simple and reliable manner, without requiring human intervention, thus reducing reaction time and the risk of error.

[0007] According to one feature of the invention, in the second step, the measuring and / or control machine compares at least one measured value with at least one nominal value of the part, and then implements the third step when the difference between the at least one measured value and the at least one nominal value goes above a determined threshold.

[0008] It is understood that the nominal value corresponds to a standard, expected value for the part. Furthermore, the first and second parts exhibit a manufacturing tolerance, that is, a dimensional range around the nominal value within which the dimensions of said part are considered acceptable. Thus, it is understood that the threshold corresponds to a value where it is established that the dimensions of the part approach the maximum and minimum limits of the manufacturing tolerance. Therefore, when the difference between the measured value and the nominal value of a given dimension exceeds the determined threshold, the measuring and / or control machine implements the third step of the process in order to determine the corrective action(s) to be taken so that the subsequent parts machined by the machining center used in the first step move away from the maximum or minimum limits of the manufacturing tolerance and closer to the nominal value.It is therefore understood that the control process makes it possible to anticipate and avoid dimensional overruns of machined parts, outside the manufacturing tolerance.

[0009] According to an alternative of the invention, in the second step, the measuring and / or control machine compares at least one measured value with at least one nominal value of the part, the measuring and / or control machine stopping at least one machining machine that machined the part measured in the second step when at least one value measured in the second step is outside a manufacturing tolerance of the corresponding nominal value.

[0010] When at least one measured value is outside the manufacturing tolerance, it is necessary to stop the machining machine from which said machined part originates in order to allow the intervention of a production line operator and to stop the production of defective parts.

[0011] According to one feature of the invention, the first part and the second part machined respectively by the first machining machine and the second machining machine have dimensions of identical nominal value.

[0012] According to one example of the invention, the first and second parts are identical, intended for the same machining operation. The process is then advantageous because it allows the correction to be sent to the machine that caused the dimensional drift, and to verify that it is indeed this machine that received the correction.

[0013] According to one feature of the invention, during the second stage, the measuring and / or control machine also identifies at least one part machined during the first stage by the machining machine.

[0014] According to one feature of the invention, the fourth step includes a sub-step of verifying that the correct correction received by the machining machine during the third step has been properly taken into account.

[0015] In the fourth step, the machining center acknowledges the integration of the correction received in the third step, for example, by sending an electronic signal back to the measuring and / or control machine. After verifying that the correction was correctly received by the correct machine, the process checks that the correction has been properly implemented in the machining center's program.

[0016] According to another example of the invention, verification of the correction's application by the machining center is carried out by measuring a machined part produced by the machining center that received the correction. The new measurements taken by the measuring and / or control machine must be consistent with the correction applied. It is therefore understood that, following the fourth step, the machining center repeats the first step, applying the correction received during the third step.

[0017] According to one feature of the invention, in the first step, the first machining machine machines the first part and the second machining machine machines the second part; in the second step, the measuring and / or control machine measures the first and second parts and associates one or the other of the machining machines with the measured parts; and in the third step, the measuring and / or control machine determines machining corrections from the measurements of the first and second parts and transmits these corrections respectively to the first and second machining machines implemented in the first step.

[0018] We understand that we take advantage of the process in that it allows the measuring and / or control machine to check at least two machined parts on the production line and in particular to determine and send corrections to two separate machining machines but manufacturing identical parts, while verifying the receipt of the correct corrections at the correct machining machine.

[0019] According to one feature of the invention, during the fourth step the measuring and / or control machine verifies the correct receipt of the correction of the first machined part and the correction of the second machined part respectively by the first machining machine and the second machining machine.

[0020] The invention also relates to a production line comprising a first machining machine and a second machining machine, the first machining machine being intended to machine a first part and the second machining machine being intended to machine a second part, the production line comprising a measuring and / or control machine, the production line implementing the machining control process according to any one of the preceding characteristics.

[0021] According to a characteristic of the production line, the first part and the second part have identical nominal value dimensions.

[0022] The invention also relates to a computer program comprising program code instructions for the execution of the second step of the process up to the fourth step of the process according to the preceding characteristics when the program is executed on the measuring and / or control machine, according to which, based on information collected on the production line according to the preceding characteristics, the computer program is configured to associate one and / or the other of the machining machines with the part measured in the second step, the computer program being configured to verify the correct receipt of the correction(s) sent to said machining machine.

[0023] Other features, details and advantages of the invention will become clearer upon reading the description given below by way of example in conjunction with drawings in which: [ Fig 1] is a schematic view of a production line implemented by the process according to the invention; [ Fig 2 ] is a schematic view of a machined part produced by the first or second machining machine; [ Fig 3 ] is a flowchart of the steps in the process of controlling the machining of parts on the production line.

[0024] It should first be noted that while the figures illustrate the invention in detail for its implementation, they can, of course, also be used to further define the invention, if necessary. It should also be noted that these figures only show examples of embodiments of the invention. Finally, the same reference numerals designate the same elements throughout all the figures.

[0025] There figure 1Figure 1 illustrates a production line according to the invention, comprising a first machining center 2a, a second machining center 2b, and a measuring and / or inspection machine 4 for the parts machined by these machines. More specifically, the first machining center 2a machines a first part 6a, and the second machining center 2b machines a second part 6b. These machining centers 2a and 2b are, for example, CNC machines or CNC machining centers connected so as to transmit or receive information electronically.

[0026] According to one feature of the invention, the first part 6a and the second part 6b have identical dimensions. In other words, the first machining center 2a and the second machining center 2b are configured to machine parts 6a and 6b that are structurally and dimensionally identical. In the example of the invention of the figure 2, the first part 6a and the second part 6b are pistons, it being understood that this example is not limiting of the invention and that this piston is used only to illustrate the process according to the invention.

[0027] As can be seen on the figure 1 The measuring and / or control machine 4 is positioned at the output of the production line 1, following a direction of advancement S of the machining of parts 6a, 6b, represented by arrows on the figure 1In other words, the measuring and / or control machine 4 is located downstream of the first machining center 2a and the second machining center 2b and is capable of measuring and / or controlling the first part 6a and / or the second part 6b as they exit their respective machining centers 2a and 2b. More precisely, the measuring and / or control machine 4's function is to ensure that at least one of the parts 6a and 6b machined on the production line 1 does not exceed a manufacturing tolerance and, in particular, to detect when said part 6a and 6b approaches the maximum and minimum limits of the manufacturing tolerance. For example, the measuring and / or control machine 4 is a laser measuring center or a center using a probe capable of measuring a dimension.

[0028] Thus, according to the invention, the production line 1 implements a method for controlling the machining of at least the first part 6a machined by the first machining center 2a and / or the second part 6b machined by the second machining center 2b, the method implementing at least the measuring and / or control machine 4. The control method will now be described in relation to the figures 1 to 3 of the demand.

[0029] It should be considered that the following process is implemented in a situation where the first machining machine 2a and / or the second machining machine 2b require at least one corrective action during the operation of the production line 1. In the case where the parts machined by the first machining machine 2a and / or the second machining machine 2b have dimensions conforming to the nominal values ​​of the part, the machining control process as described below is not implemented, and in particular a third and a fourth step are not implemented.

[0030] The process includes at least one first step 100 in which at least one of the machining centers 2a, 2b machines one of the parts 6a, 6b. In the illustrated example of the invention, during the first step 100, the first machining center 2a machines the first part 6a and the second machining center 2b machines the second part 6b. Each of the machined parts 6a, 6b is then conveyed along the production line 1 to the measuring and / or control machine 4. According to one example of the invention, the first machined part 6a may be a first piston, and the second machined part 6b may be a second piston. It is understood here that the first machining center 2a and the second machining center 2b machine parts that are structurally and dimensionally identical.

[0031] It should be considered that each of the first machining machine and / or the second machining machine can machine at least two parts that are different from a structural and dimensional point of view and that the process according to the invention can be applied to at least one of the parts produced by at least one of the machining machines.

[0032] In a second step 200, the measuring and / or control machine 4 measures at least one part 6a, 6b machined during the first step 100 and associates one or the other of the machining centers 2a, 2b with the part 6a, 6b thus measured. To this end, the measuring and / or control machine 4 includes a computer program 8 comprising program code instructions enabling the execution of the second step 200 of the process up to the fourth step 400, the third step 300 and the fourth step 400 being described later in the detailed description of the invention. Thus, when the computer program 8 is executed on or by the measuring and / or control machine 4, it enables said measuring and / or control machine 4 to associate at least one of the machining machines 2a, 2b with the part 6a, 6b measured and machined during the first step 100 on the basis of information collected on the production line 1.

[0033] The identification of the machining machine 2a, 2b which originated the part 6a, 6b measured by the measuring and / or control machine 4 may be, for example and without limitation, the reading of a code inscribed on said part 6a, 6b and associated with the machining machine 2a, 2b, or the reading of a barcode affixed to said part 6a, 6b, or even the identification of said part 6a, 6b by radio frequency.

[0034] Thus, following the illustrated example of the invention to figures 1 to 3In the second step 200, the measuring and / or control machine 4 measures the first part 6a and the second part 6b machined by said machining centers 2a, 2b in the first step and associates both the first machining center 2a and the second machining center 2b respectively with the first part 6a and the second part 6b. Furthermore, in this second step 200 of the process, the measuring and / or control machine 4 identifies at least one part 6a, 6b machined in the first step 100, here the first part 6a and the second part 6b.

[0035] It is understood in particular that during this second step 200, the measuring and / or control machine 4 is able to associate at least one machined part 6a, 6b which it measures with one of the machining machines 2a, 2b, in particular thanks to the computer program 8 which it contains.

[0036] Thus, during the second step 200, the measuring and / or control machine 4 compares the measured value of at least one of the parts 6a, 6b with the nominal value of said part 6a, 6b. In the illustrated example, the at least one measured value is a measured diameter D of the first part 6a, here the first piston, compared to the nominal value, here a reference diameter of the first part 6a. The same reasoning applies in particular to the second part 6b, forming here the second piston, and more generally to all dimensions of interest of the part being measured.

[0037] Following the comparison between the measured value and the nominal value, the process according to the invention implements the third step 300 when the difference between at least one measured value and at least one nominal value exceeds a predetermined threshold. It is understood that the threshold corresponds to a value where the dimensions of parts 6a, 6b approach the maximum or minimum limits of the manufacturing tolerance. In an application example, the manufacturing tolerance is 1 mm and the threshold value is 0.2 mm. Thus, when the difference between the measured value of the first part 6a (here, the measured diameter of the first piston) and the nominal value (here, the reference diameter of the first piston) exceeds the threshold value of 0.2 mm, the production line 1 implements the third step 300 of the process. It is also understood that the same reasoning applies to the second machined part 6b.

[0038] During the third step 300, the measuring and / or control machine 4 determines at least one machining correction from at least one measured value of at least one of the first part 6a and / or the second part 6b during the second step 200. It is understood in particular that the machining correction makes it possible to reduce the difference between the measured value of the next parts machined by the machining machine 2a, 2b, of which the measured part 6a, 6b has the difference between its measured value and its nominal value which exceeds the previously determined threshold, and the nominal value of said next parts.According to the example of the invention and in the case where the comparison of the measured values ​​of the first part 6a and the second part 6b with the nominal values ​​respectively of the first part 6a and the second part 6b, as described above, exceeds the determined threshold, the measuring and / or control machine 4 determines at least one machining correction for each of the first machining machine 2a and the second machining machine 2b so that the next parts machined by these machining machines 2a, 2b have measured values ​​closer to the nominal values, i.e. far from the limits of the manufacturing tolerance.

[0039] Once at least one correction has been established by the measuring and / or control machine 4, and in particular by the computer program 8 it contains, said measuring and / or control machine 4 transmits said correction exclusively to at least one machining center 2a, 2b implemented during the first step 100. More specifically, and according to the example of the invention, the measuring and / or control machine 4 sends the correction resulting from the measurement of the first part 6a to the first machining center 2a and the correction resulting from the measurement of the second part 6b to the second machining center 2b. According to a non-limiting example of the invention, the transmission of the correction can be carried out via a computer network linked to the computer program 8, or by electronic communication between the measuring and / or control machine 4 and the machining centers 2a, 2b.

[0040] Furthermore, the process includes an alternative step 350 to the third step, called stop step 350, implemented following the comparison between at least one measured value with at least one nominal value by the measuring and / or control machine 4. More specifically, during this alternative step 350, if the measured value is outside the manufacturing tolerance, the measuring and / or control machine 4 stops at least one machining machine 2a, 2b which implements the first step 100 of the process and informs a production line operator that maintenance is required.In other words, when one of the first part 6a and / or the second part 6b has at least one dimension which is out of manufacturing tolerance, the computer program 8 of the measuring and / or control machine 4 commands the stop of the first machining machine 2a and / or the second machining machine 2b concerned, the recalibration of the latter requiring for example the intervention of the operator of the production line 1.

[0041] Following the third step 300, the production line 1 implements the fourth step 400 of the process during which the measuring and / or control machine 4 verifies the correct reception of the corrective by at least one machining machine 2a, 2b implemented during the first step 100. Furthermore, the fourth step 400 may include a sub-step 410 of integration or correct taking into account the corrective received by the machining machine 2a, 2b during the third step 300.

[0042] It is then understood that, during the fourth step 400, on the one hand the machining machine 2a, 2b receiving the corrections apply them to the next machined parts, and on the other hand, that the measuring and / or control machine 4 ensures that the correction has been sent to the machining machine 2a, 2b whose next machined parts required a correction, as determined during the third step 300, and only to this machining machine 2a, 2b.

[0043] According to the invention, the measuring and / or control machine 4 verifies the correct reception of the correction by the first machining center 2a and of the correction by the second machining center 2b. The means implemented by the computer program 8 for verifying the correct reception of the correction by the correct machining center 2a, 2b may, for example, consist of the emission by said machining center 2a, 2b of one or more initial signals sent to the measuring and / or control machine 4. The measuring and / or control machine 4 also verifies that the correction has been taken into account by the machining center 2a, 2b, that is, the implementation of the correction in the program of the machining center 2a, 2b. This verification of the correction's implementation may consist, for example, of the emission of one or more secondary signals sent to the measuring and / or control machine 4.

[0044] According to another example of the invention, the means implemented by the computer program 8 for verifying that the correction has been taken into account by the machining center 2a, 2b can consist of measuring a part machined by the machining center 2a, 2b receiving the correction, after receiving said corrections. In other words, after the correction has been sent and once the machining center 2a, 2b receiving the correction has again implemented the first step 100 of the process, the measuring and / or control machine 4 applies the second step again to verify that said correction has been taken into account by the machining center 2a, 2b receiving the correction. Following the fourth step, the production line returns to the first step of the process.

[0045] It is understood that the machining control process as described above allows for the verification of the dimensions of at least one machined part on a production line comprising at least two machining centers. In particular, it allows for the anticipation of dimensional drift in said machined part by applying a corrective action and verifying that the relevant machining center has indeed received the corrective action. Furthermore, it allows for the automatic determination of corrective actions to be applied to one of the machining centers using a computer program implemented in the measuring and / or control machine, while ensuring that these corrective actions are sent to the correct machining center within the production line.

[0046] The invention as described above is not limited to the means and configurations exclusively described and illustrated, and also applies to all equivalent means or configurations and to any combination of such means or configurations, in accordance with the characteristics as defined in the claims.

Claims

1. Method for inspecting the machining of at least a first part (6a) machined by a first machining machine (2a), the method implementing at least one machine (4) for measuring and / or inspecting said at least first part (6a), the method comprising at least: - a first step (100) in the course of which the machining machine (2a) machines one of the parts (6a), - a second step (200) in the course of which the measuring and / or inspecting machine (4) measures the part (6a) machined during the first step (100) and associates one and / or the other of the machining machines (2a, 2b) with the part (6a) thus measured, and - a third step (300) in the course of which the measuring and / or inspecting machine (4) determines at least one machining correction based on the measurements of the part (6a) and transmits this correction to the machining machine (2a, 2b) that machined the part (6a) measured in the second step (200), and - a fourth step (400) in the course of which the measuring and / or inspecting machine (4) checks that the correction has been properly received by the machining machine (2a, 2b) that machined the part (6a) during the first step (100), characterized by inspecting the machining of a second part (6b) machined by a second machining machine (2b) and the checking in the fourth step (400) comprising checking that the correction has been properly received by the first machining machine (2a) and / or the correction has been properly received by the second machining machine (2b); the fourth step (400) comprising the machining machine acknowledging the integration of the correction received during the third step (300) by sending a reply consisting of an electronic signal to the measuring and / or inspecting machine (4), and the checking by the measuring and / or inspecting machine (4) taking into account the correction made by the machining machine comprising checking that the correction has been implemented in the program of the machining machine (2a, 2b).

2. Inspecting method according to the preceding claim, in the course of which, during the second step (200), the measuring and / or inspecting machine (4) compares at least one measured value with at least one nominal value of the part (6a, 6b), then implements the third step (300) when the difference between the at least one measured value and the at least one nominal value exceeds a determined threshold.

3. Inspecting method according to Claim 1, in the course of which, during the second step (200), the measuring and / or inspecting machine (4) compares at least one measured value with at least one nominal value of the part (6a, 6b), with the measuring and / or inspecting machine (4) shutting down the at least one machining machine (2a, 2b) that machined the part (6a, 6b) measured in the second step (200) when the at least one value measured during the second step (200) is outside a manufacturing tolerance of the corresponding nominal value.

4. Inspecting method according to any one of the preceding claims, wherein the first part (6a) and the second part (6b) machined by the first machining machine (2a) and the second machining machine (2b), respectively, have dimensions with an identical nominal value.

5. Inspecting method according to any one of the preceding claims, wherein, in the course of the second step (200), the measuring and / or inspecting machine (4) also identifies the at least one part (6a, 6b) machined during the first step (100) by the machining machine (6a, 6b).

6. Inspecting method according to any one of the preceding claims, wherein the fourth step (400) comprises a sub-step (410) of checking that the correction received by the machining machine (2a, 2b) during the third step (300) has been properly adopted.

7. Inspecting method according to any one of the preceding claims, in the course of which, during the first step (100), the first machining machine (2a) machines the first part (6a) and the second machining machine (2b) machines the second part (6b), during the second step (200), the measuring and / or inspecting machine (4) measures the first part (6a) and the second part (6b) and associates one or the other of the machining machines (2a, 2b) with the measured parts (6a, 6b), and, during the third step (300), the measuring and / or inspecting machine (4) determines machining corrections based on the measurements of the first part (6a) and of the second part (6b) and transmits these corrections to the first machining machine (2a) and to the second machining machine (2b), respectively, used during the first step (100).

8. Production line (1) comprising a first machining machine (2a) and a second machining machine (2b), the first machining machine (2a) being intended to machine a first part (6a) and the second machining machine (2b) being intended to machine a second part (6b), the production line (1) comprising a measuring and / or inspecting machine (4), the production line (1) implementing the method for inspecting the machining according to any one of the preceding claims.

9. Production line (1) according to the preceding claim, wherein the first part (6a) and the second part (6b) have dimensions with an identical nominal value.

10. Computer program (8) comprising program code instructions for executing the second step (200) of the method up to the fourth step (400) of the method according to any one of Claims 1 to 7 when the program is executed on the measuring and / or inspecting machine (4), wherein, on the basis of information gathered on the production line (1) according to Claim 8 or 9, the computer program (8) is configured to associate one and / or the other of the machining machines (2a, 2b) with the part (6a, 6b) measured in the second step (200), the computer program (8) being configured to check that the correction(s) sent to said machining machine (2a, 2b) have been properly received.