A probe structure

Abstract

A kind of probe structure, multiple piezoelectric ceramics are uniformly distributed on annular flexible PCB to form piezoelectric assembly, annular flexible PCB has connecting surface one and connecting surface two on the upper and lower surface of each piezoelectric ceramic, and is connected to electrical connection point by internal wiring of PCB;Piezoelectric assembly is placed in the inside of base, and has contact seat on it, multiple support balls are embedded in contact seat, support ball corresponds to piezoelectric ceramic one by one, probe seat is above contact seat, and support ball and the V-shaped groove of probe seat form kinematic coupling structure, compression spring one end is connected to circuit board, and one end is located in probe seat hole, to provide pre-pressure for probe seat;Insulating seat is between piezoelectric assembly and circuit board, and has multiple openings in the inside for spring probe to pass through to realize electrical connection.The utility model discloses reduce the processing difficulty of probe sensor;And not sensitive to thermal change;Reliable and durable positioning structure is designed, to ensure the service life of probe.

Description

Technical Field

[0001] This utility model relates to the field of probe sensors, specifically a probe structure. Background Technology

[0002] As a high-precision measuring tool for inspecting the dimensions and shape features of parts, the probe is widely used in machining centers, coordinate measuring machines, and other processing and inspection equipment. Probes are generally small in size, integrating high-sensitivity sensing elements, a stable kinematic coupling structure, a power module, a trigger circuit module, and a workpiece contact probe. They are compact in structure, require low triggering force, and have high repeatability. Based on the sampling method, probes can be divided into contact probes and scanning probes. Contact probes generate a trigger signal very quickly upon contact with the workpiece, collecting only one data point per contact. Scanning probes can generate a variable signal indicating the offset of the stylus relative to the probe body, producing many data points corresponding to the workpiece contour per contact. This utility model belongs to the contact probe category.

[0003] US Patent 5299360A discloses a contact probe. The probe's detection and signal transmission device may include circuitry and at least one associated switch. When the probe detects the surface of a part and causes a slight displacement, it generates a trigger signal. However, the solution disclosed in this patent can only perform linear dimension detection, which has significant limitations.

[0004] Patent CN101142461A discloses a measuring probe consisting of a bendable component with a T-shaped cross-section and a strain gauge. The contact between the stylus holder and the sensor element presents a kinematic positioning form with a total of six contact points, achieving repeatable and precise reset under the action of a compression spring. When the stylus contacts the workpiece, the force applied to the ball changes, causing strain in the radial arm of the sensor element. The semiconductor strain gauge senses the strain change in real time. The strain signal is processed by the circuit and calculated by the trigger algorithm and compared with a set threshold. When the trigger threshold is reached, the probe sends a trigger signal to the coordinate positioning device and records the trigger coordinates. Due to the small size of the probe and the small trigger force (typically 0.05N~0.5N), the structural strain is very small, approximately 3~5e-6mm / mm. Ordinary strain gauges are no longer suitable, requiring small-sized, high-sensitivity semiconductor strain gauges. However, semiconductor strain gauges are difficult to manufacture and have low bonding yield, thus making the probe implementation challenging. Patent CN103189710A discloses a contact detector with a piezoelectric sensor and thermal insulation. It uses a layered piezoelectric sensor made of polymer material, fixed and positioned by two annular circuit boards made of glass fiber electrical insulation. A kinematic coupling structure consisting of a V-shaped base and radial elements converts the contact force between the detector and the workpiece into a charge generated by the piezoelectric sensor. This detector includes two detection devices: a six-point closed circuit formed by the layered piezoelectric sensor and the kinematic coupling structure. A trigger signal is generated only when the circuit is broken due to a piezoelectric signal generated by the movement of the arm assembly and the subsequent separation between the mechanical contacts. The closed circuit is used to shield against false triggering caused by vibration or other noise. A separate thermal insulation system is designed to prevent the detector from generating unwanted charges due to adverse thermal changes. The patent also discloses a triggering algorithm that uses an adder to sum the relative absolute values. The layered piezoelectric sensor used in this patent is difficult to manufacture, and the charge generated by the layered piezoelectric film is limited. Therefore, the repeatability is poor when touching at low speeds, making it unsuitable for applications requiring low-speed detection. Furthermore, the layered piezoelectric sensor is sensitive to heat, requiring the design of a thermal insulation system, which complicates the system.

[0005] US Patent No. 7516672B2 discloses a contact probe using a pressure-sensitive sensor. Specifically, the pressure-sensitive sensor is a silicon piezoresistive chip. Three sensors are evenly distributed on a circuit board at 120° intervals, each with a spherical force-transmitting element. A diaphragm has three circular holes corresponding to the positions of the spherical force-transmitting elements. The sheet metal diaphragm is 0.25mm thick and mechanically connected to a fixed body. The openings in the diaphragm exert pressure on the ball to roughly determine its position (but cannot completely fix the ball). This connection method can filter false triggering signals generated by acceleration / deceleration and vibration. The probe holder has three arms, each with a pair of parallel cylinders at its lower part, forming a kinematic coupling structure with the spherical force-transmitting elements. A compression spring above the probe holder provides pre-pressure to the kinematic coupling structure. When the probe contacts the workpiece, the contact force between the probe and the workpiece is transmitted to the sensor through the probe holder and the spherical force-transmitting elements. When the sensor detects that the force exceeds a set threshold, the probe generates a trigger signal. After the probe separates from the workpiece, it precisely returns to its original position under the action of the compression spring. This patent uses a thin sheet metal diaphragm to fix the spherical force transmission element. When the probe is disassembled and assembled, it is inevitably subjected to a large torque. After long-term use, the sheet metal deforms, the sheet metal diaphragm and the ball loosen, and the service life of the probe is reduced.

[0006] Patent CN101171493B discloses a dimension measurement probe triggering algorithm. During the probe's contact with the workpiece, signals from three strain gauge sensors are collected in real time and compared with predetermined data. The sensitivity along the X and Y directions is calculated and compared with the sensitivity along the Z direction. An algorithm ensures equal sensitivity along the three dimensions (X, Y, and Z) in all possible directions approaching the workpiece. This patented algorithm requires high microprocessor processing power and involves complex circuit design. Utility Model Content

[0007] The technical problem to be solved by this utility model is to provide a probe structure and triggering method to address the shortcomings of the existing technical field.

[0008] To achieve the above objectives, the technical solution adopted by this utility model includes the following: A probe structure comprises multiple piezoelectric ceramics 8 evenly distributed around the circumference of an annular flexible PCB 7 to form a piezoelectric assembly. The annular flexible PCB 7 has a connecting surface 19 and a connecting surface 20 on the upper and lower surfaces corresponding to each piezoelectric ceramic 8, which are connected to an electrical connection point 17 through internal traces 22. The piezoelectric assembly is placed inside a base 13, which has a contact seat 6. The contact seat 6 has multiple support balls 5 embedded in it, and the support balls 5 correspond one-to-one with the piezoelectric ceramics 8. The probe seat 4 is above the contact seat 6, and the support balls 5 and the V-groove of the probe seat 4 form a kinematic coupling structure. One end of a compression spring 9 is connected to the circuit board 3, and the other end is located in the hole of the probe seat 4, providing pre-pressure for the probe seat. An insulating seat 10 is located between the piezoelectric assembly and the circuit board 3, and has multiple openings inside for the spring probe 23 to pass through to achieve electrical connection.

[0009] Furthermore, the connecting surface 19 and connecting surface 20 of the annular flexible PCB7 are respectively attached to the top and bottom of the piezoelectric ceramic 8; the annular flexible PCB7 is provided with opening 18 and opening 21 for welding and positioning of the annular flexible PCB7 and the piezoelectric ceramic 8; in order to save internal space and avoid interference between parts, the excess part of the annular flexible PCB7 can be cut off after welding is completed.

[0010] Furthermore, the contact seat 6 is connected to the base 13 by an interference fit or adhesive bonding through a flexible cotter pin 11, thereby achieving axial and circumferential positioning of the contact seat 6.

[0011] Furthermore, the preferred connection method between the piezoelectric component and the circuit board 3 is to use a spring probe 23, and the insulating seat 10 is designed with probe positioning holes. The electrical connection points of the piezoelectric component, the openings of the insulating seat, and the electrical connection points of the circuit board correspond one-to-one.

[0012] Furthermore, the irregularly shaped sealing ring 12 provides sealing protection for the probe structure.

[0013] Compared with existing technologies, its advantages are: A new piezoelectric ceramic sensor is adopted, which has a simple structure, is easy to process, and has low cost. Based on the structural characteristics of piezoelectric ceramics, a ring-shaped flexible PCB suitable for the probe structure is designed. It can cover the piezoelectric ceramics from the top and bottom, which can play a role in heat insulation. The flexible PCB saves space compared with the rigid PCB and has reliable connection. Elastic pins are used to fix the contact seat axially and circumferentially, and the positioning structure is reliable and durable, which extends the service life of the probe. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 Schematic diagram of the main structure of the probe; Figure 2 Schematic diagram of a piezoelectric component; Figure 3 Schematic diagram of the unfolded ring-shaped flexible PCB; Figure 4 Schematic diagram of the electrical connection of the spring probe; In the attached diagram: 1. Machine fixture; 2. Fixture; 3. Circuit board; 4. Probe holder; 5. Support ball; 6. Contact seat; 7. Annular flexible PCB; 8. Piezoelectric ceramic; 9. Compression spring; 10. Insulating seat; 11. Elastic cotter pin; 12. Irregular sealing ring; 13. Base; 14. Probe; 15. Probe ball; 16. Workpiece; 17. Electrical connection point; 18. Opening 1; 19. Connection surface 1; 20. Connection surface 2; 21. Opening 2; 22. Internal trace of PCB; 23. Spring probe. Detailed Implementation

[0016] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. These embodiments are intended to provide a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention should not be limited to the embodiments set forth herein.

[0017] This utility model proposes a probe structure and triggering method. Figure 1The diagram shows the main structure of the probe, which has a fixed base 2 connected to a machine tool or coordinate measuring machine's fixture 1. The machine drives the probe to move in the X, Y, and Z directions. Inside the probe is a ring-shaped flexible PCB 7 with three pairs of connecting surfaces 19 and 20, evenly distributed in a 120° circumferential pattern. Three piezoelectric ceramics 8 are located on the connecting surfaces of the ring-shaped flexible PCB 7, with their upper and lower surfaces in contact with the contact surfaces, forming a piezoelectric assembly. Figure 2 As shown, the charge generated by the piezoelectric ceramic is conducted to the electrical connection point 17 through the internal trace 22 of the PCB. The contact seat 6 is located above the piezoelectric assembly. Three circumferentially distributed support balls 5 are embedded within the contact seat, positioned above the piezoelectric ceramic 8 and corresponding one-to-one with it. The bottom surface of the contact seat 6 is in contact with the top of the piezoelectric assembly. The contact seat 6 has multiple openings in its circumferential direction, corresponding to the positioning holes of the base 13. The openings of the contact seat 6, the positioning holes of the base 13, and the elastic cotter pins 11 are interference-fitted or glued together to achieve axial and circumferential positioning of the contact seat 6. The probe seat 4 is located above the contact seat 6. The probe seat has three V-grooves, which, together with the support balls 5, form a kinematic coupling structure, uniquely defining the position of the probe seat. A compression spring 9 is located above the probe seat 4 to provide preload. A probe 14 is connected below the probe seat 4. The probe 14 and the probe balls 15 form a probe assembly for contact detection with the workpiece. The annular flexible PCB design has multiple pairs of openings 18 and 21 for welding and positioning the annular flexible PCB and piezoelectric ceramic. To save internal space of the probe, excess parts of the annular flexible PCB 7 can be cut off after welding. The insulating base is located between the circuit board 3 and the base 13, and has multiple through holes corresponding to the electrical connection points 17 of the piezoelectric component. Spring probes 23 inside the through holes conduct the charge of the piezoelectric component to the circuit board 3 for further signal processing.

[0018] When a machine tool or coordinate measuring machine (CMM) moves the probe to probe a workpiece, the probe ball 15 touches the workpiece and generates a contact force. This contact force is transmitted to the piezoelectric assembly through the probe 14, probe holder 4, support ball 5, and contact seat 6. The three piezoelectric ceramics sense the pressure change and generate an electric charge. This charge is conducted to the circuit board 3 through the internal PCB trace 22 and spring probe 23. After processing the piezoelectric signal and comparing it with a set trigger threshold, the probe generates a trigger signal when the threshold is reached. The machine tool or CMM records the coordinate position at the trigger moment, decelerates and brakes, and moves the probe away from the workpiece, completing one contact probe. After the probe leaves the workpiece, the kinematic coupling structure returns precisely to its original position under the action of the compression spring 9, preparing for the next probe.

[0019] The kinematic coupling structure consisting of probe seat 4, support ball 5, and contact seat 6 is a known example of a Kelvin coupling structure. Its purpose is to uniquely restrict the position of probe seat 4 and achieve repeatable and accurate return. Other Kelvin structure examples can achieve the same expectation.

[0020] The piezoelectric signal trigger judgment logic is specifically a quick-response algorithm, that is, the signals generated by the three piezoelectric ceramics are processed separately, and when the amplitude of any piezoelectric ceramic signal reaches the set threshold, the probe generates a trigger signal.

[0021] Therefore, the above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A probe structure, characterized in that, Multiple piezoelectric ceramics (8) are evenly distributed on a ring-shaped flexible PCB (7) to form a piezoelectric assembly. The ring-shaped flexible PCB (7) has a connection surface 1 (19) and a connection surface 2 (20) on the top and bottom of each piezoelectric ceramic (8). They are connected to the electrical connection point (17) through the internal wiring (22) of the PCB. The piezoelectric assembly is placed inside the base (13), which has a contact seat (6). The contact seat (6) has multiple support balls (5) embedded in it. The support balls (5) correspond one-to-one with the piezoelectric ceramics (8). The probe seat (4) is above the contact seat (6), and the support balls (5) and the V-groove of the probe seat (4) form a kinematic coupling structure. One end of the compression spring (9) is connected to the circuit board (3), and the other end is located in the hole of the probe seat (4) to provide pre-pressure for the probe seat (4). The insulating seat (10) is between the piezoelectric assembly and the circuit board (3). It has multiple openings inside for the spring probe (23) to pass through to achieve electrical connection.

2. The probe structure according to claim 1, characterized in that, The connecting surfaces 1 (19) and 2 (20) of the annular flexible PCB (7) are respectively attached to the top and bottom of the piezoelectric ceramic (8); the annular flexible PCB (7) is provided with opening 1 (18) and opening 2 (21) for welding and positioning of the annular flexible PCB (7) and the piezoelectric ceramic (8); in order to save internal space and avoid interference between parts, the excess part of the annular flexible PCB (7) can be cut off after welding is completed.

3. The probe structure according to claim 1, characterized in that, The contact seat (6) is connected to the base (13) by an interference fit or adhesive bonding through an elastic cotter pin (11) to achieve axial and circumferential positioning of the contact seat (6).

4. The probe structure according to claim 1, characterized in that, The preferred connection method between the piezoelectric component and the circuit board (3) is to use a spring probe (23); the insulating seat (10) is designed with probe positioning holes, and the electrical connection points of the piezoelectric component, the opening of the insulating seat, and the electrical connection points of the circuit board correspond one-to-one.

5. A probe structure according to claim 1, characterized in that, The irregularly shaped sealing ring (12) achieves sealing protection for the probe structure.

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