WO2007028449A1

WO2007028449A1 - Stylus-type instrument

Info

Publication number: WO2007028449A1
Application number: PCT/EP2006/007052
Authority: WO
Inventors: Peggy DÖRRER; Josef Ludwig; Rainer Ziegenbein
Original assignee: Carl Mahr Holding Gmbh
Priority date: 2005-07-27
Filing date: 2006-07-18
Publication date: 2007-03-15
Also published as: DE102005035785B3

Abstract

A novel stylus-type instrument serving in particular as a roughness stylus has a basic body and a stylus arm pivotally mounted thereon. Spiral springs (14, 15) which are a seamless and one-piece component of the stylus arm are used for the mounting. The spring joint formed in this way is frictionless. It can be used not only as a pivot but also as a measuring spring in order to produce the stylus force clamping the stylus arm or its stylus tip against the workpiece surface. In addition, one arm of the stylus arm can serve as sensor opposite pole. All the functional units present on the stylus arm, with the exception of the stylus, can therefore be fashioned from a single component. This concerns the arms of the stylus arm, the sensor opposite pole in the form of the arm, the spiral springs (14, 15), which form a spring hinge for the pivotable mounting of the stylus arm, and the fastening sections (17, 18) adjoining the spiral springs (14, 15). Production is simple and reliable.

Description

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The invention relates to a scanning device, in particular in an embodiment as a roughness probe.

Touching devices, in particular roughness buttons, are known. A typical roughness probe has a base body on which a few tens of millimeters long sensing arm is mounted slightly pivotable. The probe arm may for example consist of ceramic. The probe arm has at one end a stylus which serves to scan a Werkstückober- flat. To do this, the probe is moved parallel to the workpiece surface. The stylus slides over the workpiece surface and deflects the sensing arm with respect to the main body of the Tastgeräts. The main body of the touch device can be supported by a runner on the workpiece surface. To generate a defined contact force, one or more spring elements are usually provided, which bias the scanning arm towards the workpiece surface. The installation of such devices is expensive.

Furthermore, for example, present in the pivotal mounting of the probe arm Reibeinflüsse is a source of error that can lead to significant errors especially when the probe arm is somewhat flexible. That is why he is usually formed by a stiff ceramic rod. Also, incorrect assembly of the spring element can lead to measurement errors. Furthermore, error influences can result from the sensor device, which are provided for detecting a pivoting of the probe arm. If the sensor device is formed for example by a sensor coil, which is associated with an armature plate mounted on the probe arm, a slight incorrect assembly of the armature plate can cause measurement errors.

On this basis, it is an object of the invention to provide an improved touch device.

The touch device according to the invention has a sensing arm, which is mounted on the base body via a spiral spring. The spiral spring is an integral part of the sensing arm and / or the body. This leads first to a simple structure and low demands on the assembly when mounting the probe arm on the body. Mismatches are hardly to be feared here. The precision of

Biegefeder regarding the determination of the hinge axis and the generation of a corresponding, a deflection counteracting force is completely in a section shifted the manufacturing process, which is carried out by machine. Subjective error influences are largely eliminated.

The storage of the sensing arm on the body by means of bending spring avoids errors that could occur due to bearing friction known cutting or tip bearing. Due to the frictionless mounting of the probe arm, a deflection of the same during the measurement plays no role. It can therefore have some flexibility, e.g. be formed by a thin sheet steel. The deflection is reproducible in any case and thus irrelevant. Apart from a particularly simple and clear design of the touch device and a reduction in the number of necessary parts, thus also results in an improvement in the accuracy of the Tastgerät invention over conventional devices.

The sensing arm and the bending spring as well as the basic body may consist of a metal, preferably steel.

The bending spring is formed by at least one spring portion whose thickness is less than the thickness of the remaining material of the sensing arm. In addition, this spring area can be formed by a narrow, exempt strip, which is narrower than the rest of the sensing arm. While the sensing arm and the bending spring thus consist of the same material, they have due to the geometric design of the spring region on different spring properties. By dispensing with screw points or other connections fertilize in the transition from the sensing arm to the spring area also a distortion of the bending spring is avoided. It can easily provide a largely linear and hysteresis free spring characteristic can be generated. This in turn benefits measurement accuracy and production safety.

The spiral spring can be manufactured so precisely that it not only serves as a spring joint but also as a spring

Generation of the measuring force is used. It can then be dispensed with any additional spring elements for biasing the probe arm. This further reduces the number of items required for the touch device. In addition, such a structure simplifies assembly.

As an integral part of the probe arm, a section can also be provided, which forms the opposite pole for the sensor. This section is formed for example by a flat plate portion which is integrally connected via a web to the probe arm. Preferably, the connection is seamless and seamless. The sensing arm and the opposite pole can be cut from a suitable sheet, such as steel. The counter-pole can also form a counterweight for the probe arm, so that weight forces acting on the probe arm are compensated. This, too, benefits the measuring accuracy, in particular if the scanning device is to be used in different measuring positions.

The probe arm can be connected to the base body, for example screwed or preferably welded, are. For this purpose, connecting regions are formed on the probe arm, which connect via the bending springs to the remaining probe arm. The connection areas are dimensioned so large that a welding point arranged, for example, in a corresponding opening provided in them does not cause any thermal influence on the bending spring. To connect the Tastarras to the main body can be provided an adjustable bearing. This is formed for example by exnen exempted and by squeezing screws to a small extent pivotable section. If the accuracies requirements are lower or the manufacture of the bending springs is sufficiently precise, however, such an adjustment can also be dispensed with.

Further details of advantageous embodiments of the invention are the subject of the drawing, the description or claims.

In the drawing, an embodiment of the inventive Tastgeräts is illustrated. Show it:

1 shows the probe device according to the invention in an embodiment as a roughness probe in an enlarged, longitudinally sectioned illustration,

FIG. 2 shows the basic body of the roughness scanner according to FIG. 1 in a perspective view,

FIG. 3 shows the probe arm of the roughness scanner according to FIG. 1 in a perspective view;

FIG. 4 shows the probe arm according to FIG. 3 in a partial plan view,

Figure 5 shows the probe of Figure 4 in a side and

Sectional view taken along the line VV in Figure 4, FIG. 6 shows a bending spring of the Tascarm in longitudinal sectioned representation and modified embodiment,

FIG. 7 shows the bending spring according to FIG. 5 or 6 in a cross-sectional representation in a first embodiment,

FIG. 8 shows the spiral spring according to FIG. 5 or 6 in a cross-sectional representation in a modified embodiment,

Figure 9 shows a modified embodiment of a probe arm of the roughness probe of Figure 1 in a perspective view of one of its flat sides and

10 shows the probe arm of Figure 9 in a perspective view of its other flat side.

In FIG. 1, a roughness probe 1 is illustrated as a scanning device, which serves for detecting the surface roughness of a workpiece surface and for this purpose is towed over a workpiece surface 2 indicated only schematically. For this purpose, the roughness probe 1 is dragged in a direction indicated by an arrow 3, wherein it rests on the workpiece surface 2 and slides with its runner 4 along this. The runner 4 is attached to a boom 5, which extends for example in the form of a tube or a U-profile approximately parallel to the direction indicated by the arrow 3 of a base body 6 of the roughness probe 1 away. The boom 5 may be integral part of the body 6. It is hollow and takes on an elongated sensing arm 7, which is pivotally mounted on a bearing 8.

An arm 9 of the sensing arm 7 extends to a point located above the runner 4 and carries there a stylus 10 which rests by an opening provided in the blade 4 opening 11 with its tip on the workpiece surface 2. With respect to the bearing 8 the arm 9 is an oppositely directed arm 12 opposite to the arm 9 performs an opposite pivotal movement when the sensing arm 7 pivots. The arms 9, 12 have, for example, as shown in Figures 1 and 5, preferably a uniform thickness. The sensing arm 7 is made for example of a steel sheet. However, they define a different width, as illustrated in Figures 3 and 4. While the arm 9 is more likely to form a narrow rod, the arm 12 is more like a plate. They are interconnected by a web 13 which extends through the bearing 8 therethrough. The bearing 8 is preferably formed by bending springs 14, 15 shown in FIGS. 3, 4 and 5, which are an integral part of the sensing arm 7, ie they consist of the same material as this and connect to it without a seam. The bending springs 14, 15 are arranged on both sides of the web 13 and define a common, in Figure 4 schematically indicated, hinge axis 16. They are each formed by bending regions of the sensing arm 7. The bending areas are defined by the fact that in them, as is apparent from Figure 5, the thickness D of the otherwise flat on both sides Tastarms 7 is reduced. In addition, their width B may be reduced from both ends to the middle (FIG. 4). Its width B is the lowest at the hinge axis 16. The thickness D also decreases from the ends of the respective bending areas to the center in the vicinity of the hinge line 16. On both sides of the respective bending spring 14, 15 close to areas of the sensing arm 7, which have the usual thickness D. These are a free end forming mounting portions 17, 18 and on the opposite side a neck portion 19, which merges from the bending springs 14, 15 tapering to the arm 9. At the neck region 19 also includes between the bending springs 14, 15 of the web 13.

The geometry described so far, in particular the bending springs 14, 15, can be produced by chipless forming methods as well as by machining methods or laser machining methods, as well as by a combination thereof. For example, L-shaped, the web 13 and the bending springs 14, 15 together with mounting portions 17, 18 of the remaining sensing arm 7 separating cuts 20, 21 are produced in a laser cutting process, a stamping process or other suitable separation process. The reduction in thickness of the bending springs 14, 15 can be achieved by a stamping and / or grinding process. The thickness reduction can, as Figure 15 indicates, be bilateral and symmetrical. However, it is also possible to generate the bending springs in each case only by unilateral weakening of the material of the sensing arm 7, as illustrated, for example, by a modified example of the bending spring 14 in FIG. Furthermore, the bending spring can have a uniform thickness over its entire width, as FIG. 7 indicates. However, it can also be rounded at its edges 22, 23, which brings a special robustness and security against spring breaks with it.

The main body 6 preferably has an adjustable bearing 24 for receiving the scanning arm 7. The bearing 24 is formed in the simplest case by two spaced apart and in the same plane arranged surfaces 25, 26 (Figure 2), whose size and arrangement approximately with the size and arrangement of the mounting portions 17, 18 matches. The surfaces 25, 26 are formed on a block 27, which is connected via a web 28 with the rest of the base body 6. The web 28 preferably extends transversely to the sensing arm 7 and allows a certain pivotal movement of the block 27. The pivot axis is preferably approximately parallel to the articulated axis 16 defined by the bending springs 14, 15. In order to pivot the block 27 in the desired direction, are shown in Figure 1 apparent adjustment screws 29, 30 which sit in corresponding threaded holes of the base body 6 and press with their ends against the block 27. They protrude through transverse bores 31, 32, which are introduced into the Grundkδrper 6 to form the web 28 between each other. The sensing arm 7 is preferably connected by laser welding points with the base body 6. For this purpose, one or more openings are provided in the fastening sections 17, 18. If the fastening sections 17, 18 are placed against the surfaces 25, 26 and the inner edge of the openings of the fastening sections 17, 18 is heated by means of a laser beam, a welding point is thus produced which connects the fastening section 17 with the surface 25 and the fastening section 18 with the surface 26 , The heat input into the fastening sections 17, 18 is relatively small. In particular, the torsion springs 14, 15 are spared from excessive heat so that they retain their spring properties.

In or on the base body 6, a sensor 33, for example in the form of a seated on a magnetic core 34 coil 35 is also provided. The end faces of the magnetic core 34 form with the arm 12 a relatively narrow air gap. If the sensing arm 7 swings, the width of the air gap changes. To the coil 35, for example, via the only schematically indicated plug-in device 36, an electrical line may be connected, which leads to an evaluation circuit. If necessary, the evaluation circuit can also be integrated in the roughness probe 1, so that signals conditioned on the plug-in device 36 are emitted. To obtain meaningful signals, the change in the magnetic resistance of the magnetic circuit formed overall by the magnetic circuit 34 and the arm 12 is detected and converted into a signal.

In addition to the sensor 33, an adjusting screw 37 may be provided, with which the Pos tion of the sensing arm 7 and in - special is also the arm 9 before insertion of the stylus 10 in the arm 9 is regulated.

The roughness probe 1 described so far works as follows:

To detect the roughness of the workpiece surface 2, the roughness probe 1 is positioned so that it loads with its runner 4 on the workpiece surface 2. The stylus 10 stands with its tip (which is formed for example by a fine diamond tip) also on the workpiece surface 2. The adjusting screw 37 has been previously screwed into a retracted position. The arm 12 floats at some distance below the lower end face of the magnetic circuit 34 and forms one with this

Air gap. The bending springs 14, 15 clamp the arm 9 and the stylus 10 against the workpiece surface 2. They are biased accordingly. If the roughness button 1 is now moved in the direction of arrow 3, the tip of the stylus 10 follows the roughness, so that the arm 9 performs the slightest angular movement. Accordingly, the arm 12 performs opposing slight angular movements, which are detected by the coil 35 and evaluated as a roughness signal.

The bias of the probe arm 7 and thus the force with which the stylus 10 presses against the workpiece surface 2, can be changed by the adjustment screws 29, 30 by the block 27 can be slightly pivoted with these. For example, a slight release of the adjusting screw 30 associated with a tightening of the adjusting screw 29 increases the bias. Reverse operation reduces the preload. However, as mentioned, the adjusting screws 29, 30 can also be dispensed with if the Bending springs 14, 15 made accordingly precise and the weld between the mounting portions 17, 18 and the surfaces 25, 26 is made sufficiently accurate.

In a modification of the embodiment described above, the bending springs 14, 15 may also be part of the base body 6, on which then correspondingly thin and narrow, serving as a spiral spring portions are formed. It is also possible to form the sensing arm 7 and the base body 6 including the bending springs 14, 15 arranged therebetween as a whole in one piece. However, this increases the manufacturing effort to be driven again.

While the preferred embodiment has two spaced-apart bending springs 14, 15, which are arranged on the outer edge of the widest portion of the sensing arm 7 and thus particularly well define the hinge axis, it is also possible to use only a single spiral spring. For example, this may extend over a greater part of the width of the sensing arm 7. The web 13 can be arranged asymmetrically off-center. Further modifications are possible.

As FIG. 9 and FIG. 10 illustrate, the sensing arm can also be designed in a modified form. He has instead of a web 13 webs 13a, 13b, which create a substantially rigid connection between the arms 9, 12 and define a window. In this window, the bending springs 14, 15 and the mounting portions 17, 18 are arranged. The attachment portions 17, 18 may be formed separately or, as shown, united into one piece be. The sensing arm 7 'is formed substantially symmetrically with respect to its longitudinal axis. If one of the webs 13a, 13b has sufficient rigidity, one of the webs 13a, 13b can also be omitted. This leads to an asymmetrical design. Instead of the two bending springs 14, 15, a single wide bending spring or a group of, for example, three or more torsion springs can be provided. The bending springs 14, 15 have as in the above-described sensing arm 7 has a thickness which is less than the preferably uniform thickness of the rest of the probe arm. In addition, the description of the sensing arm 7 for the sensing arm 7 'of Figure 9 and 10 applies accordingly.

A novel, in particular as a roughness probe 1-nendes keypad has a base body 6 and a pivotally mounted thereto sensing arm 7. To support bending springs 14, 15, which are seamless and integral part of the sensing arm 7. The thus formed spring joint is frictionless. It can not only be used as a swivel axis, but also as a spring for measuring the

Tastarm 7 and his Tastspitze against the workpiece surface 2 to produce exciting sensing force. In addition, an arm 12 of the sensing arm 7 serve as Sensorgegenpol. All existing on the sensing arm 7 functional units can thus with the exception of the stylus 10 from a single

Component be worked out. This concerns the arms 7, 12 of the probe arm, the sensor armature in the form of the arm 12, the torsion springs 14, 15, which form a spring hinge for the pivotable mounting of the probe arm 7, and fastening sections 17, 18 adjoining the flexure springs 14, 15.

The production is simple and reliable.

Claims

Patent claims:

1. scanning device (1), in particular for roughness measurement,

with a basic body (6),

with a sensing arm (7, 7 ') which is pivotally mounted on the base body (6),

with at least one bending spring (14), which is an integral part of the sensing arm (7, 7 ') and / or the base body (6) and which serves for the pivotable mounting of the sensing arm (7, 7 ¹ ) on the base body (6).

2. Tastgerät (1), in particular for roughness measurement,

with a base body (6),

with a sensing arm (7, 7 ¹ ) which is pivotally mounted on the base body (6),

with at least one bending spring (14), which serves for the pivotable mounting of the sensing arm (7, 7 ') on the base body (6) and as a measuring spring.

3. Tastgerät (1), in particular for roughness measurement,

with a base body (12) on which a sensor coil (35) is arranged,

with a sensing arm (7, 7 ') which is pivotally mounted on the base body (6) and on which a counter-pole (12) for the sensor coil as an integral part of the sensing arm (7, 7 ') is formed.

4. Tastgerät according to claim 1 or 2, marked thereby, that the sensing arm (7, 7 ^r ) of a metallic

Flat material is formed.

5. Bag device according to claim 1 or 2, characterized in that on the scanning arm (7, 7 ') as a spiral spring (14) a spring portion is formed whose thickness is isr less than the thickness of the remaining material of the sensing arm (7, 7').

6. Tastgerät according to claim 1 or 2, characterized gekennzeich- nee that on the sensing arm (7, 7 ') as a spiral spring (14) is formed a spring portion whose width is smaller than the width of an arm (9 or 12) of the sensing arm (7, 7 ').

7. Tastgerät according to claim 1 or 2, characterized in that the sensing arm (7, 7 ') two mutually parallel spring portions (14, 15) are formed, which define a common hinge axis (16).

8. Tastgerät according to claim 7, characterized in that extending between or adjacent to the spring portions (14, 15) at least one web (13, 13 a) having a the opposite pole (12) of the sensor coil (35) forming the flat portion of the sensing arm (7 , 7 ') carries.

9. Tastgerät according to claim 1 or 2, characterized in that the sensing arm (7, 7 ') to the base body (6) is welded.

10. Tastgerät according to claim 1 or 2, characterized ^¬ ne _t : that for connecting the sensing arm (7, 7 ' ⁾ on the base body (6) an adjustable bearing (27) is vorgesehei.