JPS63305202A - Detection head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

BACKGROUND OF THE INVENTION The present invention relates to a detection head for three-dimensionally detecting a test piece in a three-dimensional measuring or scribing device, in which a detection element in an I\using that operates by contact is used. is mounted movably in the direction of an axis of the spatial coordinate system by at least one bearing device, making it possible to convert the movement of the sensing element into its associated output signal by means of a measuring device acting in a non-contact manner. It is related to.

DESCRIPTION OF THE PRIOR ART Detection heads of the type with measuring devices that act magnetically inductively or capacitively in a non-contact manner are known (DE
-O82019895). This detection cad not only cannot be operated with sufficient sensitivity, but also requires a large measuring device. Another problem is that large moving masses are required, resulting in large deformations of the detection bin and other moving elements. Furthermore, with the decrease in detection power, a relatively large restoring force is required, which results in a large bending of the detection bin and other moving elements, especially when the object being measured is relatively Another disadvantage is that when the object is made of a soft material, the surface of the object may be deformed. Furthermore, with known types of detection heads, the problem of quickly and reproducibly returning the detection bin to its original position and obtaining a sufficiently large stroke in the direction of the detection bin when the detection force is reduced is not solved. Not yet.

OBJECTS OF THE INVENTION The objects of the invention are to provide a detection head which is as small, light and compact as possible, consists of a minimum number of elements and is simple in construction, whose measuring device is simple;
The aim is to be small and easy to manufacture, so that the measuring device operates very accurately and reproducibly, even with small fluctuations of the detection bottle.

SUMMARY OF THE INVENTION According to the invention, there is provided a housing, at least one bearing surface provided within the housing, and a sensing element movably mounted on the bearing surface, extending outside the housing and contacting an object. said sensing element is movable along an axis of a spatial coordinate system, further comprising a measuring device arranged in said housing and acting mechanically in a non-contact manner, said measuring device acts as a transducer converting the movement of the sensing element into its associated electrical output signal, and the measuring device comprises a plurality of magnetically controllable resistors fixed in the housing and mounted thereon. A detection head for three-dimensional detection of an object is provided, comprising a magnetic sensor and a counter electrode supported by the detection element and spatially arranged in proximity to and in relation to the magnetic sensor. Ru.

In this case, the measuring device can be extremely small, its space is reduced, it is lightweight and it is inexpensive. Only a small moving mass is required and even small deflections of the detection bin can be measured with great precision. The requirements for configuring the detection head as a switching feeler or a measuring feeler are also met. In the case of this measuring device, the advantage is that three measuring systems are integrated into the detection head and can provide information on the direction of detection. When configured as a measuring feeler, scanning is also possible.

Details and advantages of this measuring device will be discussed later.

As magnetoresistive elements it is also possible to use magnetically controllable resistors, in particular semiconductor resistors, which are particularly simple magnetic field elements and are inexpensive.

Preferably, the counter electrode is arranged axially offset relative to the magnetic sensor towards the free end of the sensing element protruding from the housing. In this configuration, due to the appropriate geometrical design of the magnetic sensor and the geometrical gap,
There is no need to provide a spring restoring element for restoring the sensing element to its original position after a constant flux of magnetic force has been generated and the sensing force has disappeared. Furthermore, by appropriate determination or modification of the geometrical gap between the counter electrode and the sensor, in particular the magnetoresistive element, the magnitude of the force and detection force can be carefully varied. Therefore, the restoring force can be readjusted and adapted.

The magnetic sensor may be fixed to a non-magnetic annular element, and the annular element may consist of a leaf spring. The plate slots provide a high-precision bearing arrangement, which allows large strokes and ensures precise repeatability, and is equipped with a star-shaped feeler (s), which is used as an exchangeable sensing insert.
The eccentric force (ec
centric forces) are also allowed. Since the leaf springs are symmetrical in the rotational direction and act symmetrical in the rotational direction, a similar effect is obtained when detecting around the entire circumference of the detection head. The bearing arrangement provides good mechanical stability and repeatability of the original position of the sensing element, allowing it to quickly return to its original position with low restoring forces. Therefore, when detecting, its effective detection power is also relatively small. Therefore, even if the object to be detected is a soft material, there is no risk of it deforming, and when an object with a hard surface is to be detected, the sensing bin, replaceable sensing insert and typical spherical sensor end There is no risk of deformation.

Preferably, the counter electrode is arranged on a pot-shaped holder, which is fixed in a clamping holder on the side of the leaf spring remote from the bearing ring. Due to the displacement of the magnetic sensor and its associated counterpole, an axial force component acts on the sensing element, and there is no need for a special axially acting restoring spring to restore it to a fixed original position.

The present invention will be described in detail below.

DESCRIPTION OF A PREFERRED EMBODIMENT FIGS. 1 to 3 show a detection head (10
) is shown for three-dimensional contact detection of a test piece (not shown). for example,
As described in DE-PS 1773282 or 1798419, the sensing head (10) is attached by means of a fixed journal (11) to the tool receiving part of the coordinate measuring or marking machine.

The detection head (10) has a detection element (13>) in a housing (12), which has a substantially bar-shaped part (
14) and a detection insert (15). The detection insert (15) is also substantially bar-shaped and is removably attached to the bar-shaped part (14).

The detection insert (15) has a spherical detection end (16). The portion (14) of the sensing element (13) is substantially larger than the element in the opening (1) of the housing (12).
7).

The sensing element (13) is mounted movably in the direction of the axis of the spatial coordinate system by means of a bearing arrangement (18) of the housing (12), and the sensing element (13) is mounted in the housing (12) in the direction of the central longitudinal axis (19). 12), which can also be moved in rotation about the central longitudinal axis (19) in the area of the bearing device (18).

Furthermore, a contact-free measuring device (20) is accommodated in the housing (12), which device acts between the 71 housing (12) and the detection element (13) so that these two elements are relative to each other. When displaced, the measuring device can, for example, convert the relative displacement of the detection element (13) into an output signal associated therewith. The measuring device (20) is attached to the housing and consists of a plurality of fixed magnetic sensors (21). Magnetic sensor (2
1) is configured as a resistor capable of controlling magnetism, in particular as a semiconductor resistor, and is itself well known. In this case, these are designed as magnetoresistive elements and are arranged on a circle with approximately equal angular spacing. Furthermore, the measuring device (20) has an anti-pole on the sensing element (13) associated with the sensor (21).
ole ) (22), which is located at a radial and axial distance from the sensor (21).

The counter electrodes (22) are also arranged at approximately equal angular intervals on a circle, this circle being an inner circle concentric with that of the sensor (21) and surrounded by that of the sensor (21).

Therefore, the counter electrode (22) is placed inside and the sensor (
21) is placed on the outside. Instead of this, on the contrary, the counter electrode (22) is placed outside and the sensor (22) is placed outside.
1) may be placed inside. In the illustrated embodiment, three sensors (21) and their associated counter electrodes (22) are provided. Fewer or more sensors (2
1) and its associated counterpart (22) may be provided. 1st
As shown, the magnetic sensor (21) and its associated counter pole (22) are arranged at the same axial height. Alternatively, for example, the counter electrode (22) can be placed in the housing (12) at an axial distance from the sensor (21).
It may be arranged on the free end side of the detection element (13) protruding from the detection element (13).

The sensor (21) consists of a magnetoresistive element, as such is commercially available and known. The same is true for its related opposite pole (22). Preferably, the sensor (21) is fixed on a non-magnetic annular element (23), which is fixed against movement in the pot-shaped housing (12) in the axial and circumferential directions. This annular element (23) is designed as an axial clamping element, which is intended for clamping the bearing arrangement (18). The bearing device (18) consists of an annular leaf spring (24) with a relatively thin cross-section and forms a rotationally symmetrical bearing element for the sensing element (13), which is a plate spring. It is rigidly connected to a spring (24). housing(
12) is provided with a radially projecting shoulder (25) on which the outer edge (26) of the leaf spring (24) is supported. Furthermore, an annular element (23) is provided on the opposite side of the leaf spring (24), which allows the leaf spring (24) to
is firmly pressed axially against the shoulder (25).

An internal thread (27) is provided inside the housing (12) over a certain length, and a threaded ring (27) is provided on the internal thread (27).
28) is screwed down and pressed down onto the annular element (23), which is pressed firmly onto the leaf spring (24). Furthermore, the upper open end of the pot-shaped housing (12) is closed by a lid (29), on which the fixed journal (11) is supported.

The detection element (13) has a clamping holder (30) concentric with it, which consists of two parts (31), (32) firmly clamped to each other, between which a leaf spring (24) is mounted. It is centered and firmly clamped in the area of its radially inner edge. Leaf spring (
24) extends at right angles to the detection element (13).

The detection element (13) has a bearing ring (33), which is formed in one piece with the clamping holder (30), ie with a part (32) thereof. therefore,
The bearing ring (33) is arranged on the free end side of the detection element (13) protruding from the housing (12) with respect to the leaf spring (24). The bearing ring (33) is arranged concentrically with the detection element (13) and surrounds it with a radial gap. It consists of an axially projecting annular cutting edge (34) which is pressed axially onto a seating surface (35) fixed to the housing, the seating surface (35) consisting of the proximal surface of the bearing plate (36). . Bearing plate (36
) is made of hardened material and provides a durable, precise and hard seating surface (35).

A holder (37) is provided on the opposite side of the bearing ring (33) to the leaf spring (24), and the holder (37) has a pot-shaped cross section and is molded from a soft magnetic material. The holder (37) is rigidly connected to the clamping holder (30). This is the carrier for each counter electrode (22), which is arranged in a corresponding recess (38) in the wall (39) of the holder (37).

An adjustable compression spring (40) between the housing (12), i.e. its M (29) and the detection element (13)
) is provided, consisting of a cylindrical helical spring, which allows the detection element (13) to return axially and to press the annular cutting edge (34) axially against the seat surface (35). The detection head (lO) is designed as a switching or measuring sensor. When this is configured as a measuring feeler, each sensor (21
) are sent via electrical leads to an electronic microprocessor, which converts the three readings of the deflection of the sensing element (13) into translaterial coordinates of the spatial coordinate system, namely the X-1Y- and Z-coordinates. Convert.

For conversion, the known geometrical data of the detection head (lO), in particular that of the detection end (16) of the detection element (13), are sent to the microprocessor. In the spatial coordinate system, the deflection of the detection end (16) can be accurately calculated. These values are known, and the adjustment control of the machine axes and the X-, Y-
and Z-value calculation to accurately determine the measured point.

The details of the leaf spring (24) will be explained with reference to FIG.

The leaf spring (24) has several slit-shaped opening grooves (41) extending substantially in the circumferential direction. In this embodiment, a total of three open grooves (41) are provided, which is approximately 27
It extends along a circular arc with an angle of 0° and is offset in the circumferential direction by an angle of approximately 120°, forming a substantially spiral shape. The open groove (41) and its shape and distribution ensure a symmetrical action in the direction of rotation of the leaf spring (24).

In the embodiment of FIG. 4 showing a leaf spring (124"), three slit-shaped opening grooves (141), (142), (14
There are three groups consisting of 3). Each opening groove (141) to (143) is itself arranged on a circle, and these circles are concentric. Each opening groove (141) to (1
43) extends over an angular range of approximately 90''.

The opening groove (141) placed on the smallest circular arc and the opening groove (141) placed in the same angular range on the largest circular arc.
42) are connected to each other at one end by a slit (144) which extends substantially radially and along a secant line. Opening groove on the central arc (14
3) extends from the slit (144) in the circumferential direction in a direction away from the other two opening grooves (141) and (142). Therefore, each group has a slit-shaped opening groove (143
) extends between the two opening grooves (141) and (142). Therefore, the three opening grooves (141)
Each group consisting of (143) has the shape of a bifurcated fork curved around a circle.

In an embodiment different from FIG. 1, there is no compression spring (40), and instead the magnetic sensor (21) and its associated counter pole (22) act as a compression spring (40), the axial force of the magnetic force being component causes the sensing element (13) to return axially and the annular cutting edge (34) to the seat surface (3).
5) Press it.

When detected by the detection head (10), the detection element (13) is activated by a compression spring (40) or a leaf spring (
24), the compression spring (40) or leaf spring (24) prevents the detection element (13) from rotating about the central longitudinal axis (19), which leads to the position shown in FIG. Note that the annular cutting edge (34) of the bearing ring (33) is raised above the seat (35) by a greater or lesser distance, the distance being determined by the direction and strength of the runout. The holder (37) is rigidly connected to the detection element (13).
) is displaced from the central position shown in Figure 1, and the opposite pole (
The position of 22) also changes accordingly. Holder (37)
When the counter electrode (22) moves, the resistance of the magnetic sensor changes, and the resistance of the sensor (21) is determined by the distance that the holder (37) and the counter electrode (22) are displaced. The magnetic changes occurring in the sensor (21) are then detected and evaluated by a suitable evaluation circuit and, depending on whether the detection head (lO) is configured as a switching feeler or a measuring feeler, a pulse signal or a pulse signal representing the absolute distance of the relative movement or Measured values are generated and can be processed by means of a connected evaluation circuit.

When configured as a switching feeler, the switching point is located within the measurement range between the holder (37) and the counter electrode (22).
) is electrically formed as a function of the resistance of the sensor (21) over the distance traveled. When in contact with the object to be detected and measured, the relative position of the switching point to the trigger point can be changed and this can be electrically adjusted.

This type of measuring device (20) has the advantage that by appropriate design of the sensor (21) it is possible to obtain a magnetic force that produces a constant force flux. Sensor (21) and counter electrode (22
) allows the direction of this force to be selected, without the need for a special compression spring (40). Furthermore, by changing the geometric gap between the sensor (21) and the counter electrode (22), the magnitude of that force and the detection force of the detection head (10) can be changed. The need for self-adjustment and readjustment of stability is also met.

Particularly advantageous is a measuring device (20) in which three sensors (21) and their associated counter electrodes (22) are provided and three measuring systems are integrated in the detection head (lO).

Furthermore, the measuring device (20) measures not only the absolute distance traveled (
This method has the advantage of being able to obtain information on the direction of deflection and the direction of detection, which was not previously possible.

When configured as a measuring feeler, scanning is also possible. The leaf spring (24) provides the following advantages. Leaf springs allow large strokes, ensure accurate repeatability, and tolerate eccentric forces such as those found in star sensors. Overall, a high-precision bearing element is provided, which, as before, ensures that the sensing element (13) rotates about its central longitudinal axis (19).

The restoring force provided by the compression spring (40) can be adjusted in certain situations by manual adjustment of the compression spring (40).
For example, it can be adapted whether the object to be measured is of a soft material that is easily deformed or has a hard surface.

In each case, switching points or specific measured values can be reliably reproduced. Detection from any direction can cause deflection very easily, and when the detection force disappears, a good re-centering action is also guaranteed with a reproducible return to the original position. Ru. This is due to the symmetrical effect of rotation around the entire circumference of the sensor.

During detection, the advantage is that when the mass of the moving element is small and there is no detection force, it can be quickly and reproducibly restored to its original position. Generally, the entire detection head is small, lightweight, easy to manufacture, and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the detection head of the first embodiment, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is an enlarged plan view of the leaf spring of the detection head in FIG. FIG. 4 is an enlarged plan view of the temporary spring of the second embodiment. (12)・・・・・・・・・・・・・・・・・・
・・・Housing (13)・・・・・・・・・・・・・・・
......Detection element (18)...
・・・・・・・・・・・・・・・・・・・・・Bearing device (20)・・・・・・・・・・・・・・・・・・
・・・・・・Measuring device (21)・・・・・・・・・・・・
・・・・・・・・・・・・Magnetic sensor (22)...
・・・・・・・・・・・・・・・・・・ Counter patent applicant: Choi, Stiefelmeyer Kommandit Gesellschaft

Claims (26)

[Claims] (1) a sensing element (13) is mounted movably in the housing (12) by at least one bearing device (18) in the direction of an axis of a three-dimensional coordinate system; In a detection head of a three-dimensional measuring device or marking device that converts the displacement of , in particular a plurality of magnetic sensors (21) made of semiconductor resistors, and a counter electrode (22) facing the magnetic sensor (21), the magnetic sensor (21)
is fixed to the housing, the counter electrode (22) is provided on the detection element (13), and the magnetic sensor (2
1) A detection head characterized in that it is arranged at a distance in the radial or axial direction from the detection head. (2) The detection head according to claim 1, wherein the magnetic sensor (21) is made of a polar plate. (3) The magnetic sensor (21) and the counter electrode (22)
The detection head according to claim 1 or 2, wherein the detection head is arranged on a circle at regular angular intervals. (4) The first to third magnetic sensors are provided with at least three magnetic sensors (21) and counter electrodes thereof.
A detection head according to any one of the claims. (5) The magnetic sensor (21) is arranged on a circle outside the counter electrode (22),
4. The detection head according to claim 4. (6) The magnetic sensor (21) and the counter electrode (22)
The detection head according to any one of claims 1 to 5, wherein the detection head is arranged at the same axial position. (7) The magnetic sensor (21) and the counter electrode (22)
are shifted in the axial direction, and the counter electrode (22) is arranged closer to the free end of the detection element (13) protruding from the housing (12) than the magnetic sensor (21). The detection head according to any one of claims 1 to 5. (8) The magnetic sensor (21) has a non-magnetic annular portion (23
), and the annular portion (23) is held within the housing (12) so as not to move in the axial and circumferential directions. detection head. (9) The annular portion (23) is formed as a stop portion, and a substantially annular leaf spring (24) is held by the annular portion (23), and the leaf spring (24) is attached to the housing (12). 9. The detection head according to claim 8, wherein the detection head is fixed so as not to move in the axial direction and the circumferential direction. (10) The housing (12) has a shoulder (25) projecting in the radial direction, and a peripheral portion of the leaf spring (24) is supported by the shoulder (25). The detection head according to claim 9. (11) Items 8 to 10, characterized in that a screw ring (28) is pressed against the annular portion (23) in the axial direction, and the annular portion (23) is pressed against the leaf spring (24). A detection head according to any one of the claims. (12) The leaf spring (24) is arranged substantially at right angles to the detection element (13) and is formed substantially in an annular shape, and the detection element (13)
) The detection head according to any one of claims 9 to 11, characterized in that the detection head passes through the circumferential edge of the detection head and is fixed thereto. (13) The detection element (13) is a holder (30)
13. A detection head according to claim 12, characterized in that the detection head has: a flat spring (24) sandwiched therebetween. (14) The leaf springs (24), (124) have at least a plurality of opening grooves (41), (141) extending substantially in the circumferential direction.
The detection head according to any one of claims 9 to 13, characterized in that it has: (15) A fourteenth feature in which the opening grooves (41) are each formed in a spiral shape over an angular range of about 270°, and are offset from each other by an angle of about 120°.
A detection head according to the claims. (16) Three opening grooves (141) to (143) each
Three opening groove groups are provided, each of the three opening grooves is arranged on a concentric circle and is formed over an angular range of about 90° or more, and the opening groove (141) on the minimum circle and the opening groove (141) on the maximum circle Upper aperture grooves (142) are formed at the same angular position, one end of which is connected by a substantially radially extending aperture groove (144), and an aperture groove (143) on the middle circle is connected to said radial groove (144). 15. The detection head according to claim 14, wherein the detection head extends from the opening groove (144) in the circumferential direction to the opposite side of the other two opening grooves (141) and (142). (17) A bearing ring (33) is provided at a distance around the detection element (13) and is arranged concentrically therewith, and the bailing ring (33) has an axially projecting edge ( 34), and is pressed against a seating surface (35) of a hard bearing plate (36) fixed to the housing and supported in the axial direction. Detection head described in Crab. (18) The bearing ring (33) is connected to the plate spring (
The detection head according to claim 13 or 17, characterized in that the detection head is disposed on the free end side of the detection element (13) protruding from the housing (12) relative to the detection head (24). (19) The bearing ring (33) is attached to the holder (
19. Detection head according to claim 18, characterized in that it is formed as a part of 30). (20) The counter electrode (22) is connected to the holder (30) on the opposite side of the bearing ring (33) with respect to the leaf spring (24).
20. Detection head according to any one of claims 1 to 19, characterized in that it is held on a pot-shaped support (37) which is in contact with the detection head (37). (21) The wall (39) of the pot-shaped support (37)
) is provided with a recess (38), and the counter electrode (22) is disposed within the recess (38).
Detection head according to claim 0. (22) The detection head according to claim 20 or 21, wherein the support (37) is made of a weakly magnetic material. (23) The detection head according to any one of claims 1 to 22, wherein the detection head is configured as a control feeler. (24) The detection head according to any one of claims 1 to 22, characterized in that it is configured as a measurement feeler. (25) an adjustable compression spring (40) is arranged concentrically between said housing (12) and said sensing element (13) to axially return said sensing element (13) and said bearing ring (33); edge (34)
The detection head according to any one of claims 1 to 24, characterized in that the detection head can be pressed against the seat surface (35). (26) The magnetic sensor (21) and the counter electrode (22)
) due to the axial component of the magnetic force of the sensing element (1
3) to return to the original position in the axial direction, and the edge (34) of the bearing ring (33) can be pressed against the seat surface (35). A detection head according to any one of the claims.