WO2001092815A1

WO2001092815A1 - Test device for thin holes in small workpieces

Info

Publication number: WO2001092815A1
Application number: PCT/IB2001/000937
Authority: WO
Inventors: Urs Maag; Hans Maag
Original assignee: Microcut Ltd.
Priority date: 2000-05-30
Filing date: 2001-05-29
Publication date: 2001-12-06
Also published as: AU2001258693A1; TW507063B

Abstract

The invention relates to an automatic device for testing a hole (2) in a small workpiece (1). A sensor (4) detects the recoil of the workpiece with a particular test needle pressure.

Description

Test device for thin bores in small workpieces

The invention relates to a test device for thin bores in small workpieces. Typical workpieces that can be tested using such a test device are ferrules for glass fibers.

On the one hand, ferrules are a mass product, on the other hand, they have to be highly precise in order to be used sensibly in glass fiber technology. The highest accuracy is required for the outside diameter, the concentricity of the hole and the hole diameter.

Both in the manufacture and in the quality control (testing) of the ferrules, the speed with which the work steps can be carried out is increasingly important.

Due to their mechanical structure, conventional test equipment can only be accelerated to a limited extent or - in order to be able to achieve precise test results - great efforts have to be made on the drive side. On the other hand, most of the known devices lack an accurate information about the location of the diameter taper in the bore, so that the quality of the information of the test result is limited.

JP-A-10/227602 discloses a structure in which a test needle with a protective tube is moved against a revolver on a transport carriage. The turret contains receptacles for several ferrules on a pitch circle, which can be checked for their inner diameter one after the other. The criterion that is considered in more detail in this known construction is the penetration success of the test needle in the bore. For this purpose, a sensor is placed on the other side of the revolver, which determines whether the test needle protrudes through the hole or not. It is disadvantageously not possible to determine where the diameter defect is within the bore. In addition, the sensor could also detect a test needle that was pushed through the bore while clearing work and thus provided an incorrect test result.

The structure according to the mentioned JP-A also has a further disadvantage: due to the geometric and mechanical properties of the turret and in particular due to the required pitch circle arrangement of the ferrule receptacles, accuracy problems arise. In the worst case, the different manufacturing tolerances can add up, so that the test needle does not always lie concentrically to the bore axis. This can quickly damage or wear the test needle. To avoid this, expensive manufacturing processes have to be used for the turret head.

The same problem with the manufacturing precision of the revolver occurs with the "Gauge Master 125/2500" test device from SwimaTec AG.

With regard to the desire for a quick and gentle measuring process, the problem arises because of the relatively large masses that have to be moved compared to the test needle, that these masses, once they have been set in motion, in the event of the jamming of the Needle in the bore - which occurs in all test cases in which the inside diameter is too small in at least one place - must be braked again to avoid breaking the needle. When checking the minimum permitted inside diameter, jamming or getting stuck is the norm or occurs very frequently. However, if the test needle is inserted, the entire kinetic energy must be absorbed by the system or the needle. The JP-A also deals with this problem Attempted to solve the problem by dividing the drive slide for the test needle feed into two parts. In Fig.l from JP-A this division into two is indicated by the reference numerals (9a and 9b). While (9b) is driven by a spindle (9e), (9a) is connected to the part (9b) via a tension spring (9c). If the test needle jams in a hole, the two parts (9a and 9b) separate against the force of the spring (9c). Theoretically, this is a good solution, but the test needle is not spared the interception of the kinetic energy of the part 9a and the needle holder (10 and 10a). Compared to the mass of the test needle, the mass of part 9b is a gigantic multiple - insofar as the load on the test needle is correspondingly high.

However, the more a test needle is loaded, the greater the downtimes on the testing machine and the shorter the service life of the test needle and therefore the lower the test throughput and the economy.

DE-A-4034158 also deals with a similar problem, whereby nothing is disclosed there about a sensor or a qualitative and quantitative detection. However, there is also a spring-supported test probe holder that can be used if the

The test needle allows the test needle to stand still despite the feed on the needle holder. Here, too, the coupling takes place via a spring. The separated masses are still very large in relation to the mass of the needle, but the ratio is better than in the JP-A mentioned.

From GB 2 198 236 A a device for testing the passage of a pipeline, for example a fuel line, is known. A ball, which is connected to a flexible measuring wire at the back, is blown through the line by means of an air or gas flow. If, in the event of a bottleneck, the bullet does not close it is able to happen and gets stuck, can with the help of

Measuring wire, its position within the line is precisely determined and the bottleneck can then be eliminated if necessary. For practical reasons, the scope of this solution is very limited.

DE 40 33 924 A shows a single-coordinate measuring device for measuring lengths or displacements, with an adjustable measuring force that remains constant over a larger measuring range. A measuring quill is mounted on a measuring carriage between spring elements. The relative movement between the measuring quill and the measuring carriage is superimposed on the movement of the measuring carriage via a computer and thus the absolute movement of the measuring quill is determined. This solution is very complex and can therefore only be used to a limited extent in mass production.

GB 986 841 A has disclosed a test device for automatically testing the inside diameter of pipes. The tube is pushed over a spherical test specimen, the outside diameter of which corresponds to the minimum inside diameter of the tube. If the inside diameter of the tube is smaller than the outside diameter of the test specimen, it is pushed back and an end switch is actuated. Using a pneumatic measuring device, the annular gap between the test specimen and the inner wall or the inner diameter of the tube can be determined simultaneously via a pressure drop. This test device is very complex and especially not suitable for small workpieces.

Starting from this prior art, the present invention aims to find an accurate and faster test method and a corresponding test device. According to the invention, the tasks are solved in two independent steps:

On the one hand, the workpiece is not held in bores in a part circle of a revolver, but is placed in its own holder at each test station, which was or can be brought into exact agreement with the position of the test aristocracy. In any case, this allows a perfect adjustment or an optimal position of the workpiece. This prevents the addition of any manufacturing errors and involuntary division errors in the revolver.

On the other hand, the workpiece is only held in a light, almost forceless position so that the workpiece is displaced when the test needle is clamped. Since the workpiece itself is generally small, the negative acceleration forces that occur when moving are relatively small. The forces occurring at the test needle are therefore relatively low. The test needle is protected, these desired effects are achieved.

As an independent innovation, a workpiece washing system is provided in the test device in front of the test needle device, which can be cleaned using a flushing medium, e.g. Liquid or air that cleans the bore of the ferrule.

The invention offers various detailed solutions on how the movement of the workpiece and thus the jamming of the test needle in the bore can be detected.

These solutions are protected or specified in the dependent claims and in the description of the figures.

The invention is not restricted to small workpieces and cylindrical bores, but can be used wherever it is a matter of testing small holes of any shape, which are measured by means of a measuring probe. accuracy can be checked. Under holes in the sense of the invention, slits or the like are. to understand.

Further improvements and details according to the invention, as well as variants, result from the drawings, which represent symbolic exemplary embodiments according to the invention.

It shows:

1 shows a view of a symbol drawing of a part of a complete testing device according to the invention with a spring abutment for workpiece support and an electronic sensor;

2 shows a view of an example of a test device according to the invention with a pneumatic counter bearing or sensor;

3 shows an enlarged illustration of a detail from FIG. 2 with a workpiece in the test position;

4 shows a side view of three parallel test devices on a transport arm for the parallel clocked further transport of workpieces from one station to the next;

Figure 5 is a plan view of the structure of Figure 4;

6 shows a schematic detailed illustration of a structure, comparable to FIGS. 2-5; 7 shows a plan view of a schematic structure according to FIGS. 2-6 with offset test units for testing workpieces from both sides; and FIG. 8 shows a variant of FIG. 1 with a magnetic coil sensor with electromagnetic and adjustable bias;

The description of the figures is comprehensive, the same parts are provided with the same reference symbols, components with a similar mode of operation or tasks have the same reference symbols with different indices. The figures and their description are within the scope of the invention not restrictive but merely represent exemplary embodiments. Parts which are not described in detail are known to the person skilled in the art of machining small parts, in particular to the person skilled in the manufacture and processing of ferrules.

1 shows the symbolic structure with a test needle 3a, which can be pressed into a bore 2 of a workpiece 1 by a test needle drive 14a.

In this construction, the test needle 3a is monitored by means of a sensor 15. The sensor 15 is equipped with logic, e.g. connected to a microprocessor or to a computer, which can use this position information with other information for a detailed evaluation of the bore state of the workpiece and, if appropriate, also for monitoring the test needle (condition, breakage, etc.) 3a.

The computer is also connected via a measuring line 17 to a sensor 4a, which monitors the position of an abutment 8a, which serves as a system for the workpiece 1. The workpiece is held in a holder 5a by a symbolically indicated device 6a for applying a holding force. In the simplest case, this device 6a is merely the weight of the workpiece. As is known per se, variants are pneumatic, electromechanical or magnetic holding means.

The sensor 4a can or the like via magnetic, optical, capacitive, inductive or the like. Sensor systems. The abutment 8a is held in its rest position by a spring 9a, which thus forms the limitation of the bearing surface for the workpiece 1. The spring 9a is supported at its other end against a tension bearing 10, the position of which can be regulated via an adjusting screw 13. For this purpose, the set screw 13 is rotatably mounted in a thread 12 in a fixed reference wall 11. ω ω to μ *

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the relative position to the overall system. This sensor is implemented, for example, by a test needle guide 23, which is constructed comparable to a workpiece 1 and has an optimal bore 41 for guiding the needle 3b. The test needle guide 23 is provided with a transverse bore or a transverse slot 42, which connects to a sensor line 43. The sensor line 43 is connected to a pressure regulator 21 and to a — preferably piezo pressure sensor 44.

If the test needle 3b is located outside of or behind the transverse slot 42, air flows out of this via the front part of the bore 41 in the direction of the workpiece 1. This causes a low pressure at the pressure sensor 44. However, as soon as the test needle 3b closes the transverse slot 42 or its access to the bore 41, the pressure at the sensor 44 increases. This references the test needle tip with the position of the drive 14b. When the test needle 3b is advanced further, it penetrates the workpiece 1 and pushes it against a piston 24 until it stops. This references the position of the workpiece. If, when the test needle 3b is advanced further, a constriction in the bore 2 of the workpiece 1 is detected, this constriction can be localized in its axial position via the stepper motor 14b.

A holder 5b holds a workpiece centered with respect to the test needle 3b via a centering bed 39 and a suction mechanism 40. It was placed there by means of transport arm 22. For this purpose, the transport arm has a vacuum suction connection 35, by means of which a workpiece 1 can be transported in a suction recess 36. On the other hand, the workpiece 1 is juxtaposed with a pneumatic sensor 4 with a pressure regulator. In the test mode, the workpiece 1 is supported on this sensor 4b which, when a certain impact force of the test needle 3b is exceeded, clears the way for the workpiece and the thrust interrupts. The detailed structure can be seen in the enlarged representation according to FIG. 3.

A cylindrical piston 24 has, on the one hand, a sealing ring 46 and, on the other hand, peripheral air ducts 26 for the escape of air when the piston 24 is pushed back. This protrudes from a pressure chamber 25, in which it is biased in the holding or sealing direction of the sealing ring 46. A pressure regulator enables the corresponding setting. When overcoming the pneumatic pressure force, i.e. when the support effect of the piston 24 collapses, the pressure chamber is depressurized via the channels 26 or there is a pressure drop and this is detected and used as a control signal.

The use of compressed air both with the sensor 4b and with the test needle 3b is advantageous in that the compressed air has a cleaning effect when it flows over the components and through the bores.

On the other hand, it is also within the scope of the invention to replace the pneumatic sensors and controllers with other, known detection devices.

The structure of the transport bar 22 can be seen from FIG. Suction recesses 36a-d are arranged in division steps which correspond to the distance between the test station modules 31a-c. These suction recesses 36 each take up a workpiece 1 and transport it one step further when the transport bar 22 is conveyed on. This transport takes place through two bearing disks 28a, b, on which the transport bar 22 is articulated by means of crank pins 30a, b.

5 indicates a workpiece positioner 32. Devices can be arranged comparably along the straight line, through which the outer diameter and given if the eccentricity of workpieces 1 is measured. Any measuring systems known per se, such as optical o. the like in question.

The workpiece positioner 32 has at least one receiving bore 48 into which the workpieces 1 can be inserted. A motor 49 positions the respective bore 48 relative to the suction recesses 36 and a slide pushes the workpieces 1 out of the bore 48 into the suction recesses 36. This mechanism allows the test device to be mechanized to a high degree. Alternatively, a robot arm or manual insertion of the workpieces can be provided.

Fig. 6 shows the structure in enlarged detail. The drive 14b pushes the test needle 3b, which is guided in a test needle guide with breakage monitor 23, via the spindle drive 19 and drive rod 18. The bore 41 in the guide 23 is connected to a transverse bore 42 which is connected to a sensor line 43a which leads to a pressure sensor 44 and is likewise connected to a throttle for air supply 21a. This allows the test needle 3b to be detected as soon as it closes the transverse bore 42 in the bore 41.

The piston 24 has air channels 26 which allow the air to escape from the pressure chamber as soon as the sealing ring 46 has lifted off. Accordingly, after a certain force on the workpiece has been exceeded, the pressure drop can be measured by opening the piston via the sensor line 43b. The sensor line 43b is also acted upon by a throttle 21b with compressed air and connected to a pressure sensor 45.

8 shows a variant of a measuring sensor 4c with a plunger coil 34, in which a thrust anchor 8b serves as an abutment. The push anchor 8b is comparable to the structure according to Fig.l supported by a spring 9b. Its resistance can optionally be set electronically via a voltage regulator 33.

The following list of reference symbols is part of the description of the figures.

LIST OF REFERENCE NUMBERS

Workpiece, thin bore a, b Test needle a, b, c Sensor a, b Bracket a, b, device for applying the holding force, mechanical control a, b abutment, anchor spring, insert bearing Reference wall, thread Set screw a, b Drive for test needle Sensor for test needle logic ( Microprocessor or computer) measuring line drive rod spindle drive test needle head a, b, throttle for air supply transport arm, transport bar test needle guide with breakage monitoring piston pressure chamber air channels vernier allowed via cross bar 50 height adjustment of the holder 5b a, b bearing disc a, b transport drive a, b crank pin a, b, c Test station module workpiece positioner Voltage regulator for pre-tensioning or measuring sensitivity adjustment plunger coil vacuum suction connection suction recesses for positioning and transporting the workpieces vacuum hose pivot centering bed suction mechanism, works counter clocked if necessary with vacuum suction connection 35 bore cross bore or cross slot a, b sensor line pressure sensor pressure sensor sealing ring

Mounting hole for motor, cross bar, cross shaft, is used to adjust the bracket 5b laterally. Drive motor for transport arm. 22 Timing belt, swiveling removal arm takes the tested workpieces and feeds them computer-controlled to the collection containers 55, which are assigned to the test result. The collecting containers 55 thus contain directly quality-sorted workpieces after the test. a-f collecting container symbolically another measuring station for diameter, eccentricity, length, weight etc. Test probe holder

Claims

claims

1. Device for checking the diameter quality of a thin bore (2) in a small workpiece (1) with at least one machine-controlled test needle (3), a holder (5) for the workpiece (1) and at least one sensor (4) for detecting the blocking of the test needle (3) in the bore (2), characterized in that the holder (5) is equipped with a device (6) for applying a holding force and / or resistance force, and that the holder ( 5) is designed so that the workpiece (1) in the holder (5) under the thrust of the test needle (3) can be moved as soon as the test needle (3) clamps in the bore (2) of the workpiece (1), the Sensor (4) of the holder (5) or the workpiece (1) is assigned so that it makes the start of the displacement movement of the workpiece (1) and / or the overcoming of a certain resistance force detectable.

2. Device according to claim 1, characterized in that the sensor (4) with the mechanical control (7) is fed back in such a way that the exact displacement path (s) of the test needle (3) is determined automatically with respect to the rest position of the workpiece can be and the machine control (7) or the test needle (3) is monitored by sensors.

3. Device according to claim 1 or 2, characterized in that the sensor (4) during operation directly on the workpiece (1) by optical, capacitive, inductive, magnetic, pneumatic, hydraulic or the like. Measures whose shift is detected.

4. Device according to one of the preceding claims, characterized in that the sensor (4b) around a - preferably biased - pneumatic piston (24) summarizes, the pneumatic bias is preferably adjustable or adjustable.

5. Device according to one of the preceding claims 1 to 3, characterized in that the sensor (4c) comprises an electromagnetic plunger (34) and an armature (8b) displaceable therein, armature (8b) and coil (34) preferably to oppose a relative displacement path to a voltage-frequency or power-dependent and in particular adjustable (33) or adjustable resistor (9b).

6. Device according to one of the preceding claims, characterized in that the test needle (3) is assigned a position sensor (15).

7. Device according to one of the preceding claims, characterized in that a plurality of test needle stations

(31) are arranged along a straight line, along which straight lines a transport arm (22) is provided, which along a division with - e.g. pneumatic or electromechanical - holding means (36) for workpieces (1) and clocked can be driven, the holding means (36) preferably comprising vacuum suction connections (35) for receiving and releasing the workpieces (1).

8. The device according to claim 7, characterized in that the transport arm (22) is mounted on both sides and uniformly in the manner of a crankshaft on a respective bearing disc (28) and the double radius of the articulation point (30) of the transport arm (22) to the pivot point (38 ) each bearing disc (28) corresponds to a dividing step on the transport arm (22), where appropriate the articulation point (30) - for example via an eccentric - is adjustable.

, Device according to one of the preceding claims, characterized in that each test needle (3) has its own Ne holder (5b) with a centering bed (39) for the workpieces (1) is assigned, which is preferably equipped via a suction mechanism (40) for positioning and holding the workpieces (1).

10. Device according to one of the preceding claims, characterized in that the test needle (3) in a guide component (23) of a, the structure of a workpiece (1) comparable structure, radially guided and axially freely displaceable therein.

11. Device according to one of the preceding claims, characterized in that along the straight line - preferably at the beginning or between two test stations (31) - at least one test device for the outside diameter and / or the concentricity and / or the length of the workpieces (1) and / or a workpiece positioner (32) and / or a cleaning station is arranged.

12. Device according to one of the preceding claims, characterized in that the test needle stations (31) - preferably offset - are arranged on one and on the opposite side of the straight line, so that the workpieces (1) can be checked from both sides, and / or that the test needle stations (31) are modular and each represents a complete test unit.

13. A method for checking the diameter quality of a thin bore (2) in a small workpiece (1) with at least one machine-controlled test needle (3) and a holder (5) for holding the workpiece (1), characterized in that the workpiece is placed in the holder (5), the test needle (3) is pushed into the bore (2) of the workpiece, and that on

Workpiece (1) or on the holder (5) overcoming a holding force or the start of a displacement movement it is detected, from which it is inferred that the test needle (3) is clamped in the bore (2) and, if appropriate, the location of the clamping point within the bore (2).

14. A method for checking the diameter quality of a thin bore (2) in a small workpiece (1) with at least one machine-controlled test needle (3) and a holder (5) for holding the workpiece (1), characterized in that the workpiece (1) before inserting the test needle (3) at least in its bore (2) using a flushing medium - eg. Liquid and / or air - is cleaned, and / or that the length and / or the diameter and / or the eccentricity is measured automatically in a complex machine structure prior to measurement using a test needle (3).