DE2416120A1 - METHOD OF MEASURING GEOMETRIC PARAMETERS OF MECHANICAL WORKPIECES - Google Patents

Description

Patent attorneys

Dr. Ing. H. Neqondank Dipl. Ina. H. Hw-J: Oi ,! Γη - '=. W. Schmitt

TelefCXi 5380586

FINIKE ITALIMfA MAiRPOSS
Soc.in Accomandita Semplice
di Mario Possati & C.

Via Saliceto, 13 March 11th 1974

4OO1Q Bentivoqlio (BO) / Italy Lawyer File M-2942

Method for measuring geometric parameters of mechanical workpieces

The invention relates to a method for measuring geometric Parameters of mechanical workpieces with a cylindrical surface and another surface of rotation that has a circular Have cross-section and aligned coaxially to the cylindrical surface should be; In particular, the invention is directed to a method for measuring concentricity and roundness of valve guide bores and valve seats in internal combustion engines.

In the manufacture of mechanical workpieces, you get more and more to believe that it is useful and very often inevitable,

409846/0284

both because of the quality of the workpieces as well as make with regard to working safety of the built-up with the workpieces devices exact size measurements. This is particularly the case in the manufacture of motor vehicles.

Although it has always been necessary in automobile manufacture to use suitable measuring equipment to carry out very precise and complicated measurements on workpieces that have been taken out of production according to random laws or other criteria, it is now shown with a large output of workpieces per working hour the tendency _/ that an increasing number of test measurements should be carried out on each of the workpieces produced. However, if the entire production is to be subjected to test measurements, automatic or semi-automatic facilities must be made available that can measure the workpieces without slowing down or interrupting the production process, but are by no means labor-intensive.

On the other hand, however, many workpieces have such a shape Height or weight that can hardly be followed this trend.

'■ In internal combustion engines equipped with valves

^; Ever greater demands are placed on the good sealing seat of the valves on their seats, not only with regard to the service life, the effectiveness, the power output of the internal combustion engine, but also in particular with regard to the

-3-

409846/0284

Reduction of air pollution. Indeed it is through enhancement the valve sealing effect improves combustion and thus reduces pollution.

The invention has therefore set itself the task of providing a method for measuring the concentricity and the roundness in a more mechanical manner Workpieces such as valve guide bores and valve seats of internal combustion engines or comparable mechanical workpieces Components.

The invention is of course also to an apparatus for implementation of the proceedings. Particular attention is paid to the fact that, with the aid of the method and the device, concentricity and roundness can be measured fully automatically or semi-automatically in mass production processes.

This object is achieved according to the invention in that at least two first size measurements on suitable cross-sections of the cylindrical Surface and at least two second size measurements made on one and the same cross-section of the rotating surface the first and second test measurements substantially along the entire circumference of the associated cross-section are carried out, and the measurement data of the first and second ■ test measurements to determine the concentration error of the two Areas and the measurement data of the second test measurements to determine the roundness of the rotating surface with the circular nominal cross-section are processed.

409846/0284

When measuring a valve guide bore and the associated With the frustoconical valve seat, the first test measurements are made on two different cross-sections of the valve guide bore and the second test measurements are carried out on the same cross-section of the valve seat.

The apparatus for performing the method is characterized in that means of the same for supporting the to be measured workpiece and for positioning relative to a movable supporting and protective device for a plurality of measuring elements zurrt detecting linear dimensions or deviations from predetermined Sollabmaßen are provided _f that could be the lementen a first and a second measuring element, preferably contact sensor for measuring the suitable cross-sections of the cylindrical surface and a third and fourth measuring element, preferably contact sensor, for measuring the one cross-section of the rotating surface, that a drive for the support and protection device is provided such that the measuring elements can measure the circumference of the cross-sections and that the measuring elements are interconnected with electrical circuits known per se which generate signals corresponding to the detected dimensions, the output signals of the first, second, third n and fourth measuring element are connected to a first evaluation circuit for determining the concentricity error and the output signals of the third and fourth measuring element are connected to a second evaluation circuit for determining the roundness.

409846/0284

The invention will now be described in more detail with reference to the accompanying figures where the same reference numerals are used for the same or equivalent components. It shows:

1 shows a basic illustration of the for determining the concentricity a valve seat with the guide bore and the roundness of the valve seat required device;

Fig. 2 is a front view of a through-formed embodiment the 'device;

Figure 3 is a side view of the device shown in Figure 2; and

Fig. 4 is a circuit diagram of the drives in FIGS. 2 and 3 device shown.

with reference to FIG. 1, a with the inventive Procedure, for example, describes a solvable measurement problem who * - that, in the determination of the concentricity between the valve seat 11 and the associated valve guide bore 12 of the head 13 an engine block and in determining the shape of the valve seat 11. The test measurements are made with the aid of an insert 14 performed, der.aus a cylindrical section 15 and a frustoconical section 16. These two sections protect invisible sensors 17> 18, 19 and 20 with movable ones Sensory arms. After the head 13 'one still further down

"6-

409846/0204

Descriptive manner has been positioned, the insert 14 is lowered down so that it is in the position shown in FIG ^ assumes. The insert 14 is then rotated once about its axis. The sensors 17, 18, 19 and 20 are freely movable in the directions shown by the arrows. The feelers 17 and 18 are at right angles to the axis 21 of the insert 14 movable, while the sensors 19 and 20 at an angle of 45 to the

Axis 21 are displaceable, the displacement directions a point D on the axis 21 intersect.

For detecting displacements of the insert 14 in the axial direction a further sensor 22 is provided which emits a compensation signal.

The displacements detected by sensors 17, 18, 19, 20 and 22 " are converted into electrical signals. For this purpose, each measuring sensor is preferably provided with an inductive position transducer and processing circuits assigned so that the actual feeler lever together with these components represents an electronic measuring sensor. ! represents. These electronic sensors are known per se; therefore, the invention is not limited to their construction or their operation and for the same reason a more detailed description of the same is dispensed with here.

The output signals of the sensors 17, 18, 19, 20 and 22 are with

denoted by reference numerals 17, 18, 19, 20 and 22, respectively. The "roundness" M _{1 of} the valve seat 11 is determined according to the following equation:

409846/0284

19 + 20

γτ

- 22

Max

19 + 20

γτ

- 22

(D

The concentricity error M "of the valve seat 11 with respect to the Valve guide bore 12 is calculated according to the following equation :

M ₂ =

s- = b + c ^17th

19-20

a + b + c

Max

18-f7

a + b + c

19-20

fT

a + b + c

min

The meaning of the quantities a, b, c is explained below.

The form error M. is essentially the maximum variation in the dimension of the cross section of the valve seat 11, with which the Sensors 19 and 20 cooperate as the drawer 14 rotates. When it is determined, a compensation takes place with the aid of the signal 22 possible axial displacements of the withdrawable part itself.

It can be shown that the concentricity _{error M 2} defined by equation (2) represents the eccentricity of the cross-section of the valve guide bore 12 with which the sensor 18 cooperates with respect to the intersection of this cross-section with the line which connects the point D with the center of the Cross section of the valve guide bore 12 connects with which the sensor 17 cooperates.

-8th-

409846/0284

The quantities a and b used in equation (2) are the distance of the cross-section measured by the sensor 18 from that of Sensor 17 measured cross-section or from the cross-section measured by sensors 19 and 20. The size c represents the distance the center of the last-mentioned cross-section from point D.

In an analogous manner, the eccentricity of each (any) of the three cross-sections, which from the measuring sensor 17, from the measuring sensor 18 or scanned by the sensors 19, 20, with respect to the intersection of the connecting line between point D and the center point of another cross-section or with respect to the intersection of the connecting line of the midpoints of the other two Cross-sections are determined.

As can be seen from FIG. 4, the measuring sensors 17, 18, 19 and 20 lie on the same meridian plane of the insert 14.

It can also be shown that possibly occurring displacements of the axis of the insert 14 during the measurement both the measurement of the concentricity error in the axial as well as in the transverse direction can not influence.

To measure the form error, the offsets in the axial direction are compensated for by the output signal of the measuring sensor 22; other offsets do not significantly affect the measurement of the form error M (runout).

409846/0284

In Fig. 1, the dashed line 24 represents a cable that connects the outputs of the sensors with electronic evaluation circuits 25 and 27, which can determine the form error M. and the eccentricity error M ₂ according to equations (1) and (2) . The evaluation circuits can also include suitable display devices.

The in FIGS. 2 and 3 shown device has a frame 30 for a measuring table 31, the support rails 34 and 34a and Carries side walls 35 and 35a via crosspieces 32 and 32a. The side walls 35 and 35a form together with an upper end

plate 36 a housing into which the head 13 can be slid on the support rails 34 and 34a.

Furthermore, the measuring table 31 carries two vertically arranged cylindrical Columns 37 and 37a on which two carriages are slidably arranged. The carriages are made of cylindrical Sleeves 38 and 38a, which are connected to one another by a cross strut 39 and an upper end plate 40.

The upper ends of the columns 37 and 37a are connected by clamping pieces 41 and 41a, respectively, to a stand 42, which in turn is connected to the Measuring table 31 is screwed. The end plate 40 carries a motor 43 which is connected to the insert 14 via a belt pulley 44 connected pulley 45 via a belt-46 drives. The pulley 45 is connected to a spindle 47, which in turn is rotatably mounted in an outer sleeve 48 which is connected to the cylindrical sleeves 38 and 38a. The spindle 47

409846/0284

carries the insert 14 via two flexible connections 49 and 50. In the case of small dislocations, this suspension behaves ■ like a double universal joint. A hose 51 takes electrical and pneumatic lines.

Two compressed air cylinders 53 and 53a are used to apply the head 13 against reference elements, two of which are elements 54 and 54a in 2 and another reference element 54b in FIG. 4 are visible.

The device is by means of three operating levers 56, 57 and 58 actuated. The stand 42 supports a shaft 60 on which a pulley 61 is mounted, which serves as a guide for two flexible Belt 63 and 64 is used (cf. FIGS. 3 and 4). Both straps 43 and 64 are attached at one end to a counterweight 66 while the other end of the belt 63 on the piston rod 67 of the piston 68 of an air cylinder 69 and the other end of the belt is attached to a rod 70 which is firmly connected to the cross strut 39.

The piston rods of the compressed air cylinders 53 and 53a are pressure ' assigned elements that are required for transferring the head 13 into the measuring position and holding the head in the same are.

4 shows the piston rod 72a, the piston 73a and the pressure element 74a of the compressed air cylinder 53a. Also is 4 shows a compressed air cylinder 76, its piston

409846/0284

is connected to a piston rod 78 extending on both sides. One end of the double piston rod 78 carries a
Punch 79, while the other end of the double piston rod with
the measuring sensor 22 of a correspondingly arranged measuring head 80
working together. (The probe 22 was introduced in connection with FIG. 1 ").

The compressed air cylinders 53, 53 a, 69 and 76 are supplied with compressed air from a compressed air source 82 via associated valves 83, 84 and 85. The valves 83, 84 and 85 are operated with the aid of the operating levers 56, 57 and 58. The following interlocks are provided between the levers: The lever 57 can only be actuated after the lever 56 has been actuated and the lever 58 can only be actuated after the levers 56 and 57 have been actuated In addition, the actuating lever 58 is subject to a locking dependent on the position of the piston 77 in the compressed air cylinder 76, which is shown by the dashed line 90. Such locks for the actuating levers 56, 57 and 58 are known and can be, for example, ratchet wheels (not shown) are accomplished on the associated axes of rotation
Acting lever.

The device works as follows:

The head 13 is in that of the side walls 35, 35a and the end plate 36 formed housing while sliding on the support

-12-

409846/0284

rails 34 and 34a inserted. By operating the lever 56, the valve 83 is opened and therefore the pressure element 74a is raised and the other pressure element assigned to the piston of the cylinder 53 on the head 13 and press it against the reference elements 54, 54a and 54b. Thereafter, the lever 57 is pressed down and thus the valve 84 is opened. The punch 79 is raised and when the head 13 is in a correct measuring position and the valve guide bore with regard to the dimensions, the shape the inclination of the axis does not show any deviations, the punch 79 is completely inserted into the valve guide bore 12 inserted. Only in this case can the third lever 58 also be actuated thereafter. If the stamp 79 is not complete can enter the valve guide bore 12, builds up in the locking line shown by the dashed line 90 a pressure which leads to an engagement of the second locking of the lever 58, which has already been described above has been.

On the other hand, if this lock does not engage, the lever can 58 are pressed down so that the drawer 14 is lowered. In this case it is ensured that the steps 15 and 16 of the insert 14 into the valve guide bore 12 and the space of the valve seat 11 can enter without damage or jamming are possible. The lower end of the Section 15 of the insert 14 leads the stamp 79 back, but remains in contact with it. After that, a mechanical one stops Reference element · or a microswitch (not shown) the

409846/0284

Lowering of the insert so that it is in the one shown in FIG Location remains. Thereafter, the motor 43 is actuated to the drawer 14 once around itself depending on one not to rotate the reference element shown. The measurements described in connection with FIG. 1 are carried out here. Thereafter the motor 43 rotates the insert 14 back in the opposite direction and the operator brings the actuating lever 58, 57 and 56 successively return to their rest position, so that the device is again in the initial state required for a measurement is moved back.

While the drawer 14 is rotating and measurements are being taken possibly occurring displacements of the insert itself in the axial direction by the measuring head 80 output signal is compensated, as already mentioned above has been mentioned.

To simplify the illustration, the one shown in FIGS. 2 and 3 shown Device only able to measure a valve seat and the associated valve guide bore. It is clear that at a device to be used in production, several drawers are provided for measuring all valve seats and associated valve guide bores of a head. It is on the other hand also possible to provide only a single slot and

the measurements on several valve seats one after the other under suitable! to make a relative shift between the insert and the head.

! It is also possible that the number of sensors and assigned : th converter can be enlarged in each slot. So

409846/0284

can preferably protrude on each of the two in the case of a valve guide bore with a sufficiently large diameter

mentioned cross-sections of the valve guide bore two sensors are arranged diametrically opposite one another. Also can be the number the sensor scanning the valve seat can be increased.

In this way, the accuracy and / or the definition of the information relating to the measurement are increased; of course leads this at increased costs and a more complex evaluation circuit.

It should also be clear that the device described above can be fully automated and that the pneumatically operated measuring and control elements are also suitable electrical switching arrangements can be replaced.

409846/0284

Claims (9)

Claims 1.) Method for measuring geometric parameters of mechanical Workpieces with a cylindrical surface and a second rotating surface that have a circular cross-section and is to be coaxially aligned with the cylindrical surface, characterized in that at least two first Size measurements on suitable cross-sections of the cylindrical surface and at least two second size measurements on one and the same cross-section of the surface of revolution being made, the first and second test measurements being substantially are carried out along the entire circumference of the associated cross-sections, and the measurement data of the first and second Test measurements to determine the concentricity error of the two surfaces and the measurement data of the second test measurements for Determination of the roundness of the turning surface with the circular target cross-section can be processed. 409846/0284 2. The method according to claim 1, in which a valve guide bore and the associated frustoconical valve seat are measured are to be, characterized in that the first test measurements on two different cross-sections of the valve guide bore and the second test measurements on one and the same cross section of the valve seat can be carried out. 3. Device for carrying out the method according to claim 1 or 2, characterized in that devices (32,34,35, 53,53a) for supporting the ausζumessenden workpiece (13) and for positioning the same relative to a movable support and protection device ( 14) for several measuring elements (17, 18, 19, 20) for detecting linear dimensions or deviations from predetermined nominal dimensions are provided that for the measuring elements a first and a second measuring element (17, 18) for measuring the suitable cross-sections of the cylindrical surface and a third and a fourth measuring element (19, -20) for measuring the one cross-section of the rotating surface include that a drive (42,44,47,69) for the support and protection device (14) is provided in such a way that the measuring elements can scan the circumference of the cross-sections, and that the measuring elements are interconnected with known electronic circuits (25, 27), the signals (TT, T £, T§ , 20) according to the detected dimensions ßen generate, the output signals (TT, TS ^, T ^, 20) of the first, second, third and / fourth sensors (17; 18; 19; 20) to a first evaluation circuit (25) for determining the concentricity error (M ₂ ) and the A09846 / 028A Output signals (Ϊ9 ", ^ Ο) of the third and fourth measuring element (19, 20) can be switched to a second evaluation circuit (27) for determining the roundness (M,). 4. Apparatus according to claim 3, characterized in that the measuring elements (17,18,19,20) are contact sensors. "5. Apparatus according to claim 3 or 4, characterized in that the devices for supporting the workpiece to be measured and for positioning the same guides (34,34a) for transferring the workpiece (13) into the measuring position, Positioning reference elements (54,54a, 54b) working together with the workpiece, pressure elements (53,53a, 74a) for the Pressing the workpiece against the reference elements and pre-testing devices (76,79) include which pre-testing devices determine whether the movable support and protection device (14) transfers to its measuring position without errors can be. 6. Device according to one of claims 3 to 5, characterized in that that the support and protection device is an insert (14) consisting of two sections (15,16), the Shaping of one section (15) of the shape of the cylindrical surface and the shape of the other section the shape of the rotating surface of the workpiece with
speak. and that the sections' one by a suitable j ' \ Drive (67,66) axially movable spindle (47) are connected, which can bring the insert into the measuring position, 409846/0234 and that the spindle (76) is rotatably supported and by a Drive (43) is rotatable so that the measuring elements (17,18,19,20) can scan the circumference of the cross-sections of the workpiece. 7. Device according to one of claims 3 to 6, characterized in that that the spindle (47) the two sections (15,16) of the insert (14) via flexible connections (49,50) wearing. 8. Device according to one of claims 3 to T _1, characterized in that the pressing elements (74a) for pressing the workpiece (13) against the reference elements (54,54a, 54b) and the drive for the axial displacement of the spindle (67) can be acted upon via control and locking devices (56,83,57,8.4,58, 85,86), which can be actuated in a chronological order and with certain locking. 9. Device according to one of claims 3 to 8, characterized in that that at least one measuring element (22) for the detection of possible axial displacements of the support and protection device (14) provided during the scanning of the circumference of the cross-sections for the output of a compensation signal is. 409846/0284 4i Blank page