TW201933012A - Method for determining positional errors of drilled holes and securing the drilling process - Google Patents

Abstract

In order to specify a method for determining positional errors of drilled holes (14) which are to be made in a workpiece (13) by means of a processing machine (3), which method is cost-effective and easy to handle and permits the user to determine, assess and optimise the production quality of drilled holes (14), it is proposed that during a positioning process of the processing machine (3) for producing a drilled hole (14), information from position encoders (7, 8, 9) of drive axles (4, 5, 6) is recorded by a control computer (1), from which information the control computer (1) of the processing machine (3) calculates and stores the positional errors of the drilled hole (14) at the moment of starting the drilled hole (14) as a difference between the SETPOINT position and the information of the position encoders (7, 8, 9).

Description

Position error measurement method, device for opening holes and its application

The invention relates to a method for measuring the position error of a hole opened on a workpiece by a processing machine

Hole position error is an important quality criterion when drilling printed circuit boards. Care should be taken when measuring hole position error. Position error should be measured as soon as possible after the hole is formed, so as to quickly identify defective holes and maintain the lowest possible defect rate , And can quickly eliminate the possible failure of the processing machine.

US 6384911 B1 discloses "an apparatus and method for measuring the position error of holes on a printed circuit board". The conventional device has a scanner for optical measurement and a measurement positioning table located below the scanner. The printed circuit board with holes drilled in advance can be placed in this device to use the scanner and the computer connected to the scanner to determine the hole position error.

The disadvantage of the conventional device is that the position error measurement for the hole on the printed circuit board is often delayed compared to the opening of the hole, and it occurs outside the processing machine. In most cases, information about the state of the machine during opening is not considered. This cannot avoid that many defective printed circuit boards may have been manufactured before the defect holes are identified, and it is difficult or impossible to infer the source of the failure. In addition, since the measuring machine and the processing machine are mostly not in the same space, a logistics process is also required to transport the printed circuit board to be measured from the processing machine to the measuring machine. Also need to consider is that the measuring machine There will be additional investment and operating costs. In addition, trained personnel are required to operate the measuring machine.

The object of the present invention is to provide a method for measuring the position error of a hole opened in a workpiece by a processing machine, using information from a position sensor to optimize a processing machine for opening a hole, and a method for opening a hole The above-mentioned devices are low in cost, easy to operate and allow users to measure, evaluate and improve the product quality of the holes.

This purpose is achieved by the characteristics of independent request items 1, 9 and 12. A description of advantageous embodiments can be found in the appended request item.

According to the method of the present invention, during the positioning of the processing machine for opening holes, the control computer of the processing machine records the information of the position sensor of the drive shaft, and according to the information, the control computer The position error of the hole is calculated and stored in the form of the difference between the nominal position and the recorded information of the position sensor at the instant the hole is opened. The hole position error is provided in this way without having to measure the hole on a separate measuring machine. The advantage lies in the fact that the measurement information is provided directly during the opening of the hole, and it can quickly respond to possible deviations. Generally speaking, based on the position sensors of the X drive shaft and the Y drive shaft and the corresponding nominal position components, two position errors of X deviation and Y deviation with respect to the hole position, respectively, are calculated. As a supplement, a Z deviation that can be measured based on the Z-axis position sensor and the corresponding nominal position component can also be considered. In some cases, the above deviations are also combined into a single characteristic value in the form of total deviation or total error.

In an advantageous embodiment of the invention, it is provided that the processing machine carries out the positioning process with the workpiece. In this way, the workpiece (such as a printed circuit board) to be bored is located in the processing machine during positioning, and the hole is opened in the workpiece during positioning. Correspondingly, during the opening of the hole, the position error of the hole has been determined.

In an alternative advantageous technical solution of the method, it is provided that the processing machine performs the positioning process without a workpiece. Correspondingly, during the positioning process, there is no workpiece in the processing machine, and no real hole is opened during the positioning process. In this way, the position error of the hole to be opened can be identified without the need to open a real hole, and the workpiece and/or tools are not required. This is particularly advantageous for the low-cost establishment or optimization of the processing machine, because there is no manufacturing cost for the test workpiece, which usually must be disposed of as waste.

Another advantageous embodiment of the method proposes that the control computer calculates n position errors xi into a process capability index cpk according to the following formula, where OSG is the upper limit of the acceptability criterion of the position error, and USG Is the lower limit of the acceptability criterion of the position error.

In this way, statistical observation of the position error of the opened hole is realized. This observation can be made for several holes of one workpiece, several holes of several workpieces, and/or corresponding holes of different workpieces. In this way Produce excellent characteristic values in order to continuously inspect the quality of the hole position that can be achieved by the processing machine. Alternatively, the machine capability index cmk can also be determined. The machine capability index is not directed to the specific drilling process and the hole position error related to the drilling based on the above formula, but considers any positioning process and predicts for this Acceptability criteria OSG and USG. It is worth mentioning that the above formula for realizing statistical observation by cpk value is only exemplary. Within the scope of the present invention, other statistical observations can also be made, such as adjusting the factor before s ("3" in the above example).

In another advantageous technical solution of the method, it is set as follows: the control computer displays the position error of the hole as a single value on an operation panel of the control computer. In this way, the machine operator is provided with information about the current position error of the opened hole, and the machine operator can, for example, interrupt the production process if the deviation is too large.

Another advantageous embodiment of the method provides that the control computer displays the position error of the hole as a scatter plot on the operation panel of the control computer. This kind of presentation can display the position errors of a large number of holes in a compact figure. This presentation method can be applied to several holes of one workpiece, several holes of several workpieces, and/or corresponding holes of different workpieces.

In an advantageous embodiment of the present invention, it is provided that the control computer displays the position error of the hole as a histogram on the operation panel of the control computer. In particular, such a presentation method can display the position errors of a large number of holes compactly in one graph by axis division. This type of presentation can also be applied to several holes and Several holes of one workpiece and/or corresponding holes of different workpieces.

Another advantageous technical solution of the method provides that the control computer displays the process capability index cpk on the operation panel of the control computer. In particular, this presentation method can analyze the position error over a long period of time. It can also display the previously determined cpk value in order to analyze the possible change of hole position error over a long period of time.

Another advantageous embodiment of the method provides that the position error of the hole and/or the process capability index cpk are provided on the server of the machine controller. Provide position error and/or cpk value with information technology on a server that can also be connected to the Internet, whereby the above information can be provided to upstream, parallel, or downstream internal or external services, such as machines, in the sense of Industry 4.0 Research and development, machine maintenance or quality assurance.

According to the present invention, the information of the position sensor is used to optimize the processing machine for opening a hole, as follows: during positioning of the processing machine for opening a hole, the control computer of the processing machine Record the information of the position sensor of the drive shaft, based on the information, the control computer calculates and stores the opening of the hole in the form of the difference between the nominal position and the information of the position sensor The position error of the hole at an instant, wherein the position error is compared for different system states of the processing machine, so that the system state can be evaluated and on this basis, the position deviation is determined to be small when the position error is acceptable System state or the system state with the highest productivity. In this way, the optimization measures implemented on the machine and causing the system state to change can be evaluated and compared with each other based on the measured position errors. This can help the user achieve a system with the smallest possible position error State, and this is often worth doing. Similarly, the process variables that are responsible for the productivity of the processing machine can also be increased, such as the travel speed, acceleration, and acceleration rate, etc., which will often cause larger hole position error (the reason is, for example, the vibration of the processing machine) when the increase is increased, until There is an acceptable hole position error. In this way, the productivity of the processing machine can be optimized at a lower cost and in an extremely easy-to-operate manner, without having to manufacture test parts. Based on the above-mentioned application proposed by the present invention, the machine can also be regularly checked to compare with the initial system state after startup, so as to identify possible wear on the machine early.

A further solution of the above embodiment of the present invention provides that the control computer also records and stores the current, force, and/or torque of the drive shaft during the positioning process. In this way, additional information about the system performance of the drive device is configured for the measured position error, so that the change in the positioning behavior recorded by the processing machine can directly correspond to the drive axis that caused the change, because the above change is specifically displayed on the relevant axis Measurement data.

In another advantageous technical solution of the application, the setting is as follows: the different system states of the processing machine are defined by changing control parameters, adjusting processing programs, and/or replacing components of the processing machine. The advantage of the application according to the invention is in particular that the above-mentioned changes and adjustments of the processing machine can be checked quickly and especially using the system's own components, and these changes and adjustments usually change the system state and system performance, and thus the positioning behavior of the machine .

In the device of the present invention, it is set as follows: the control computer records the position of the drive shaft during the positioning process for opening the hole Information of the sensor, based on the information, the control computer calculates and stores the hole at the moment when the hole starts to be opened in the form of the difference between the nominal position and the information of the position sensor Position error. The advantage of the device of the present invention is that information about the positioning behavior of the device can be determined based on the system's own components and information, without the need for additional external measuring machines. This can quickly make statements about the positioning behavior of the device, and these statements already exist during the drilling process.

In another advantageous technical solution of the device, it is set as follows: the control computer records additional external measurement sensors, such as a current sensor, a force sensor, a pressure sensor, a temperature sensor, Acceleration sensors, sound sensors and/or sensors for detecting material contact. By expanding the device in this way proposed by the present invention and recording additional information by the control computer, a more in-depth analysis of the positioning behavior of the device can be performed. This type of expansion is particularly meaningful in the context of troubleshooting or within the scope of R&D or optimization. Sensors (such as force sensors) used to detect material contact can very accurately determine the point in time when the material enters, such as the contact between the drill and the workpiece, even if there is a certain fluctuation in the thickness of the material or there is unevenness in the workpiece.

Another advantageous embodiment of the device proposes that the sensor for detecting material contact is constructed as an electrical contact sensor, and its implementation is that both the processing tool and the workpiece are in electrical contact, and Thereby, when the drill is in contact with the workpiece, the circuit is closed. By expanding the device in this way as proposed by the present invention, the material contact can be quickly and accurately determined. Among them, the contact is recorded by making electrical contact between the drilling tool of the processing machine and the workpiece to be processed, and thereby closing the loop when the materials are in contact. borrow The loop closed by the contacting drilling tool and the contacting workpiece is continuously monitored by the current sensor of the control computer so that the control computer can detect the material contact. Alternatively, force sensors can also be used to detect material contact.

1‧‧‧Control computer/CNC controller

2‧‧‧Operation panel/monitor

3‧‧‧Processing machine/printed circuit board drilling rig

4‧‧‧Drive shaft/Linear drive shaft X

5‧‧‧Drive shaft/Linear drive shaft Y

6‧‧‧Drive shaft/linear drive shaft Z

7‧‧‧Position sensor/(linear) displacement sensor X

8‧‧‧Position sensor/(linear) displacement sensor Y

9‧‧‧Position sensor/(linear) displacement sensor Z

10‧‧‧Drill shaft

11‧‧‧Processing tool/drill

12‧‧‧Processing table

13‧‧‧Workpiece/PCB

14‧‧‧hole

15‧‧‧Acceleration sensor/(drill shaft) vibration sensor

16‧‧‧Acceleration sensor/(processing table) vibration sensor

17‧‧‧Temperature Sensor/(Processing Table) Temperature Sensor

18‧‧‧Temperature Sensor/Temperature Sensor (of drive shaft X)

19‧‧‧sensor/electric contact sensor

20‧‧‧Force sensor

The embodiments of the present invention are explained in detail below with reference to the drawings. Among them: Figure 1 is a perspective schematic view of the unique structure of the present invention used to measure the hole position error; Figure 2 is a scatter diagram of the hole position error measured in accordance with the present invention in the XY plane; and Figures 3A and 3B are based on this Histograms of hole position errors measured by the invention in the X direction (Figure 3A) and Y direction (Figure 3B).

FIG. 1 shows a schematic structure of the present invention for measuring hole position errors in a perspective view. The CNC controller 1 with the monitor 2 is connected to a printed circuit board drilling machine 3, which has three linear drive shafts 4, 5, 6 for the X direction, Y direction, and Z direction. Within the scope of the present invention, an embodiment having more than three shafts can also be used. Each of these drive shafts 4, 5, 6 has linear displacement sensors 7, 8, 9 for absolute measurement, in the form of optically scanned steel rulers, which are detected by the displacement sensor Corresponding to the current position of the drive shaft 4, 5, 6. Alternatively, a glass ruler or a magnetic length measuring system that is optically scanned can also be used within the scope of the present invention. The printed circuit board drill 3 further has a drill shaft 10 fixed to the Z-direction drive shaft 6. A drill 11 is fixed in the drill shaft 10. The PCB rig 3 can be driven by the Y direction A printed circuit board 13 is clamped on the processing table 12 where the shaft 5 moves, and a hole 14 can be opened in the printed circuit board by the drilling tool 11 in the drilling shaft 10. On the printed circuit board drilling machine 3, vibration sensors 15, 16, temperature sensors 17, 18, force sensors 20, and electrical contact sensors for identifying the contact between the drilling tool 11 and the printed circuit board 13 are also used 19.

FIG. 2 shows a scatter plot of the X-Y position error of a hole measured according to the present invention. The hole is opened on a printed circuit board by the device of the present invention. In this scatterplot, the X-Y position error of about 10,000 holes opened on the printed circuit board can be identified.

FIGS. 3A and 3B show histograms of position errors of X-direction (FIG. 3A) and Y-direction (FIG. 3B) of about 10,000 holes measured according to the present invention. The holes are opened in the printed circuit by the device of the present invention. On the board.

The application of the method of the invention is explained below.

Once the CNC program for drilling the printed circuit board 13 is started by the CNC controller 1, the CNC controller 1 records the position information of the linear displacement sensors 7, 8, and 9. When the opening 14 is started on the printed circuit board, that is, once the drilling tool 11 is drilled into the printed circuit board 13, the CNC controller 1 then based on the nominal position of the current hole and the linear displacement sensor 7, 8 based on the CNC program , 9 to determine the current position error of the hole 14. This time point can either be triggered by the Z-axis displacement sensor 9, ie, once the Z actual position coincides with the Z nominal position used to start the drilling according to the CNC program, or by detecting the actual material Touch the electrical contact sensor 19 to trigger. This hole position error determination process is implemented for each individual drilling process. The position error of the hole 14 measured in this way is controlled Controller storage. In addition, the position error is displayed on the monitor 2 of the CNC controller 1 as a single value, a scatter plot, and a histogram. At the same time, all measured position errors of the holes 14 of the printed circuit board 13 are calculated as a process capability index cpk, which states the degree of compliance with the nominal preset value. However, the above-mentioned position error measurement of the hole 14 can be used not only to evaluate the printed circuit board drilling machine 3 but also to optimize the productivity drive. Among them, the moving speed of the printed circuit board drilling machine 3 is gradually increased until the position error of the hole 14 measured according to the above method is still acceptable, and by this way, the nominal preset value is still observed with certain safety.

The above discloses the present invention for measuring the position error of a hole opened on a workpiece by a processing machine. The present invention has low cost, is easy to operate and allows the user to measure, evaluate and improve the product quality of the hole.

Claims (15)

A method for measuring the position error of a hole (14) opened in a workpiece (13) by a processing machine (3), wherein, during the positioning process of the processing machine (3) for opening a hole (14), by The control computer (1) of the aforementioned processing machine (3) records the information of the position sensors (7, 8, 9) of the drive shaft (4, 5, 6). According to the foregoing information, the control computer (1) is nominally The position error of the hole (14) at the instant when the hole (14) is opened is calculated and stored in the form of the difference between the position and the information recorded by the position sensor (7, 8, 9). The position error measurement method according to claim 1, wherein the processing machine (3) carries out the positioning process with the workpiece (13). The position error measurement method according to claim 1 or 2, wherein the processing machine (3) performs the positioning process without the workpiece (13). The position error measurement method according to any one of the preceding claims, wherein the control computer (1) calculates n characteristic values x _i for the position error according to the following formula into the process capability index cpk , where OSG Is the upper limit of the aforementioned position error acceptance criterion, and USG is the lower limit of the aforementioned position error acceptance criterion: The position error measurement method according to any one of the preceding claims, wherein the control computer (1) displays the position error of the hole (14) as a single value on the operation panel (2) of the control computer (1) )on. The position error measurement method according to any one of the preceding claims, wherein the control computer (1) displays the position error of the hole (14) as a scatter plot on the operation panel of the control computer (1) (2) Up. The position error measurement method according to any one of the preceding claims, wherein the control computer (1) displays the position error of the hole (14) as a histogram on the operation panel of the control computer (1) ( 2) On. The position error measurement method according to any one of the preceding claims, wherein the control computer (1) displays the process capability index cpk on the operation panel (2) of the control computer (1). The position error measurement method according to any one of the preceding claims, wherein the position error of the hole (14) and/or the process capability index cpk are provided on the server of the control computer (1). An application of information from a position sensor (7, 8, 9) for optimizing a processing machine (3) for opening holes (14), wherein, in the aforementioned processing for opening holes (14) During the positioning of the machine (3), the control computer (1) of the processing machine (3) records the information of the position sensors (7, 8, 9) of the drive shaft (4, 5, 6). Information, the control computer (1) calculates and stores the difference between the nominal position and the position sensor (7, 8, 9) Suppose the positional error of the instantaneous hole (14) of the aforementioned hole (14), wherein the aforementioned positional error is compared for different system states of the aforementioned processing machine (3), so that the aforementioned system state can be evaluated and on this basis, the aforementioned positional error It is acceptable to determine the system state with the smallest position deviation or the system state with the highest productivity. The application according to claim 10, wherein the control computer (1) also records and stores the current, force and/or torque of the drive shaft (4, 5, 6) during the positioning process. The application as recited in claim 10 or 11, wherein the different system states of the processing machine (1) are defined by changing control parameters, adjusting processing programs, and/or replacing components of the processing machine (1). A device for opening a hole (14) in a workpiece (13), comprising at least three drive shafts (4, 5, 6) each having at least one position sensor (7, 8, 9), at least one respectively A drill shaft (10) with a processing tool (11) and at least one control computer (1), wherein the control computer (1) records the drive shaft (4, 5, etc.) during positioning for opening a hole (14) 6) Information of the aforementioned position sensor (7, 8, 9), based on the aforementioned information, the control computer (1) is between the nominal position and the aforementioned information of the position sensor (7, 8, 9) Calculate and store the position error of the hole (14) at the instant when the aforementioned hole (14) is opened. The device according to claim 13, wherein the control computer records additional external measurement sensors, such as current sensor, force sensor (20), pressure sensor, and temperature sensor (17, 18), acceleration sensing Sensors (15, 16), sound sensors and/or sensors (19) for detecting material contact. The device according to claim 13 or 14, wherein the sensor (19) for detecting material contact is constructed as an electrical contact sensor, and its implementation is: the processing tool (11) and the workpiece ( 13) All electrical contacts occur, and thereby the circuit is closed when the processing tool (11) contacts the workpiece (13).