Measuring Head for a Tactile Coordinate Measurement Device, Method for Measuring a Work Piece with a Tactile Coordinate Measurement Device and a Coordinate Measurement Device

Abstract

A measuring head (1; 1a) for a tactile coordinate measuring device (22), in particular an exclusively tactile coordinate measuring device, which has several sensor devices (3, 5; 3a, 5a) for determining at least one measured value at least at one measuring point (15). Advantageously, a first sensor device (3; 3a) comprises a tactile sensor and a second sensor device (5; 5a) comprises an optical detecting means (19), wherein both sensor devices (3, 5; 3a, 5a) can be connected to the tactile coordinate measuring device (22) by a single connecting section (9; 9a). Advantageously, an existing tactile coordinate measuring device can be converted into a multi-sensor coordinate measuring device without structural modifications. Furthermore, the invention relates to a method for measuring a workpiece with a tactile coordinate measuring device and a coordinate measuring device.

Claims

1.-10. (canceled)

11. Measuring head (1; 1a) for a tactile coordinate measuring device (22), in particular an exclusively tactile coordinate measuring device, which comprises several sensor devices (3, 5; 3a, 5a) for determining at least one measured value at least at one measuring point (15), characterized in that a first sensor device (3; 3a) comprises a tactile sensor (4) and a second sensor device (5; 5a) comprises an optical detection means (19), wherein both sensor units (3, 5; 3a, 5a) are connectable to the tactile coordinate measuring device (22) by a single connecting portion (9; 9a).

12. Measuring head according to claim 11, characterized in that the first sensor device (3; 3a) comprises a tactile probe (4) movable in several spatial directions.

13. Measuring head according to claim 11, characterized in that either the first (3; 3a) or the second sensor device (5; 5a) can be used for a measurement without a sensor change.

14. Measuring head according to claim 11, characterized in that the second sensor device (5; 5a) comprises a light source (10) for at least partially irradiating a workpiece surface (7; 7a) as well as a differential diode (19) forming the detection means for detecting light of the light source reflected from the workpiece surface (7; 7a).

15. Measuring head according to claim 11, characterized in that the second sensor device (5; 5a) and a control device (21) of the tactile coordinate measuring device (22) form a control loop for determining the at least one measured value.

16. Measuring head according to claim 11, characterized in that the measuring head (1; 1a) is designed as a retrofit part, for the use of which no modifications to the tactile coordinate measuring device (22) are required.

17. Measuring head according to claim 11, characterized in that by using the measuring head (1; 1a), an existing coordinate measuring device (22) suitable exclusively for tactile determination of at least one measured value at least at one measuring point (15) can be converted, without further modifications, into a multi-sensor coordinate measuring device.

18. Measuring head according to claim 11, characterized in that the measuring head (1; 1a) can be exclusively used with a tactile coordinate measuring device (22).

19. Method for measuring a workpiece (8; 8a) with a tactile coordinate measuring device (22), in particular an exclusively tactile coordinate measuring device, which has a measuring head (1; 1a) according to claim 11, characterized in that at least one measured value to be determined is determined by focusing light (13) of a light source (10) of the second sensor device (5; 5a) impinging on a workpiece surface (7; 7a).

20. Method according to claim 19, characterized in that a measurement signal of the second sensor device (5; 5a) is determined by the Focault's cutting method.

21. Method according to claim 19, characterized in that the at least one measured value at the at least one measuring point (15) is determined by regulating a position of the measuring head (1; 1a) in such a way through a control device (21) of the tactile coordinate measuring device (22) that light that hits a workpiece surface (7; 7a) and light (16) reflected from the surface (7; 7a) is in focus of an optical system (14) of the second sensor device (5; 5a).

22. Tactile coordinate measuring device (22), in particular exclusively tactile coordinate measuring device, which has a measuring head (1; 1a) according claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention is explained in more detail below with reference to examples of embodiments and the accompanying drawings relating to the examples of embodiments. Showing:

[0036] FIG. 1 Measuring head according to the invention,

[0037] FIG. 2 Details of a measuring head according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] A measuring head 1 schematically shown in cross-section in FIG. 1 for a tactile coordinate measuring device not shown in FIG. 1, exclusively intended for tactile measurements in this embodiment example comprises a measuring head housing 2, in which a first, tactile sensor device 3 with a tactile sensor 4 movable in several spatial directions as well as a second, optical sensor device 5 are provided. The measuring head 1 in this embodiment is arranged at a distance 6 from a surface 7 of a workpiece 8. A connection part 9, which may be integrated in the measuring head housing 2 or attached thereto, enables an electrical, control and mechanical connection to the tactile coordinate measuring machine.

[0039] With a measuring head 1 according to the invention, the determination of a measured value at a measuring point can be carried out either by using the tactile 3 or the optical sensor device 5. Both sensor devices 3, 5 are electrically connected by the connection part 9, i.e. in particular for the power supply as well as for the transmission of control signals to a CNC controller of the existing tactile-only coordinate measuring device.

[0040] In that the measuring head 1, in particular the second, optical sensor device 5, processes control signals from the existing, exclusively tactile coordinate measuring device, the measuring head 1 is, according to the invention, favorably particularly suitable for the use with an existing exclusively tactile coordinate measuring device. In particular, the second, optical sensor device 5 and a control device of the coordinate measuring device form a control loop.

[0041] Another advantage is that an originally exclusively tactile coordinate measuring device can be upgraded to a multi-sensor coordinate measuring device by means of the measuring head according to the invention without any structural or software modifications.

[0042] Reference is now made to FIG. 2, where identical or equally acting parts with the same reference number as in FIG. 1 are specified and the letter a is added to the respective reference number.

[0043] A measuring head 1 a shown schematically in FIG. 2 in a partially cut side view comprises an optical sensor device 5a, which uses a laser light source with a wavelength of 655 nm, a collimator 11 and a sharp-edged stationary orifice 12, which is partially inserted into a beam path of the laser light source 10.

[0044] A distance of the measuring head 1 a from a workpiece surface 7a is defined in this embodiment by the so-called Focault's cutting method and additionally by laser triangulation. Light 13 of the light source 10 passes the fixed sharp-edged orifice 12 through an objective 14 onto the workpiece surface 7a and forms a crescent-shaped light spot 15 with a maximum size of 30 μm. In this embodiment, the light spot 15 corresponds to a measuring point.

[0045] Light 16 reflected from the surface 7a is directed via two mirrors 17, 18 to a differential diode designed as a detector 19. A control and evaluation unit 20 of the sensor device 5a, which is connected by a connection part 9a of the measuring head 1 a both to a schematically shown CNC controller 21 of a coordinate measuring device 22 described in a simplified manner and being exclusively tactile as well as to the differential diode 19 and laser light source 10 by control lines sends a continuous measurement signal from the differential diode 19 to the CNC controller 21, which triggers an incremental movement of the coordinate measuring device 22 in the direction of or away from the workpiece surface 7a, so that the measuring head 1a moves in the direction of or away from the surface 7a.

[0046] Due to this movement, the measuring signal of the differential diode changes continuously, i.e. it ranges, for example, between +6.5 V and −6.5 V, whereby a measuring signal of 0 V means that the light spot 15 on the workpiece surface 7a is in the focal point of the objective 14. When a signal value of 0 V is reached, the spatial position coordinate within a measuring coordinate system 23 is transmitted as a measured value at this measuring point 22 and it is stored.

[0047] It is understood that the control and evaluation unit 20 is further arranged to control the intensity of the laser light source 10, or to evaluate measurement signals from a detection means, that is, for example, the differential diode or alternatively an image sensor not shown in FIG. 2, for example a CMOS sensor.

[0048] The control and evaluation unit 20 forms the interface between the measuring head 1a and the CNC controller 21 of the exclusively tactile coordinate measuring device 22, whereby no modification of the hardware or software is required, so that a measuring head 1 according to the invention can be used with existing tactile coordinate measuring devices.

[0049] In that the CNC controller 21 of the coordinate measuring device 22 controls the measuring head 1; 1a on the basis of a control signal, a measuring head 1; 1a can be, according to the invention, designed as a retrofit part that can be used with any exclusively tactile coordinate measuring device 22 without further hardware or software modification. Favourably, an existing coordinate measuring device suitable exclusively for tactile measurements can be converted into a multi-sensor coordinate measuring device with the measuring head 1; 1a, according to the invention, without further modifications.

[0050] It is also conceivable to create a measuring method in which a material surface 7a is scanned, preferably at a scanning rate of up to 40,000 measuring points per second and at a constant distance of the measuring head 1 a from the workpiece surface 7a, which may in particular be 50 mm. A speed at which the measuring head 1 a is continuously moved over the workpiece surface 7a, a direction of movement, the constant distance as well as those positions on the workpiece surface 7a at which a punctual measurement is to be carried out are predetermined by a measuring program available on the tactile coordinate measuring device 22. When the workpiece surface 7a is scanned, a light spot 14 or a line of light moves out of the focal point of the optical system 14. During the continuous movement, a distance of the measuring head from the workpiece surface is controlled until a measurement signal of the differential diode is 0 V. When a signal value of 0 V is reached, the spatial position within a measuring coordinate system 23 is transmitted to the coordinate measuring device 22 as a measured value at this measuring point and stored.

[0051] It is understood that it can be specified either manually or by a measuring program which of the two sensor devices 3, 5; 3a, 5a is to be used.