CN222528578U

CN222528578U - Contour measuring rod mechanism

Info

Publication number: CN222528578U
Application number: CN202421380280.9U
Authority: CN
Inventors: 尹建华; 石文彬
Original assignee: Shandong Ipre Detection Technology Co ltd
Current assignee: Shandong Ipre Detection Technology Co ltd
Priority date: 2024-06-17
Filing date: 2024-06-17
Publication date: 2025-02-25
Anticipated expiration: 2034-06-17

Abstract

The utility model discloses a profile measuring rod mechanism, comprising a stylus, a measuring rod, a fulcrum and a displacement sensor, wherein the stylus is mounted on the front end of the measuring rod, the tail end of the measuring rod is rotatably mounted on the fulcrum, and the displacement sensor is mounted on the middle of the measuring rod. The utility model changes the arrangement structure of the traditional measuring rod through innovation, the tail end of the measuring rod is rotatably mounted on the fulcrum, and the displacement sensor is mounted on the middle of the measuring rod, so that the error caused by the bearing clearance at the fulcrum can be greatly reduced after such arrangement, and the measurement resolution is not lost in the same structural space.

Description

Contour degree measuring rod mechanism

Technical Field

The utility model relates to the technical field of precision measurement, in particular to a contour degree measuring rod mechanism.

Background

As shown in fig. 1, the traditional profile measuring rod mechanism comprises a contact pin 1, a measuring rod 2, a fulcrum 3 and a displacement sensor 4, wherein the structural arrangement relation is that the middle part of the measuring rod 2 is rotatably arranged on the fulcrum 3 (B), the contact pin 1 is arranged at the front end (A) of the measuring rod 2, and the displacement sensor 4 is arranged at the tail end (C) of the measuring rod 2.

The measurement principle is that when the stylus 1 slides across the surface of an object, the measuring rod 2 rotates around the fulcrum 3 due to the unevenness of the surface of the object, so that the displacement sensor 4 at the tail end detects the rotation quantity of the measuring rod 2, and then the surface contour relief of the object is restored through an algorithm.

The pivot 3 generally uses a dense ball bearing as the center of rotation, but the bearings have a common characteristic that there is a bearing play, that is, there is a radial gap X between the inner and outer rings of the bearing, as shown in fig. 2 (exaggerated schematic), the gap is generally in um level, and for ordinary applications, the gap is generally negligible, but for high precision detection devices of profile class, the error caused by the high precision detection device cannot be ignored. As shown in fig. 3, this gap is due to the fact that when the stylus 1 is inclined, its force direction F1 is perpendicular to the contact surface, and this end of the stylus 2 is subjected to a force directed obliquely to the right, the other end of the stylus 2 is necessarily subjected to a force F2 directed obliquely to the left, which force is necessarily generated by the support of the bearing outer race against the inner race. Therefore, the circle center of the bearing inner ring, namely the rotation circle center of the measuring rod, can be deduced to deviate. In the measurement, the contact surface of the stylus 1 at the start point is assumed to be in a horizontal state, and the stylus 1 at the end point is assumed to be in a state as shown in fig. 3. The movement of the stylus can be broken down into two parts, the first part being rotation of the stylus about the theoretical centre of a circle and the second part being rotation of the stylus about the tip to the condition of figure 3. The first part is linear and produces no error, and the second part is that the measuring rod produces X-size error at the point A. According to the conventional arrangement scheme, the length of the AB section of the measuring rod is twice that of the BC section, and then the nonlinear error generated by the measuring rod at the point C (namely the position of the displacement sensor) is 3/2*X.

Disclosure of utility model

The utility model aims to solve the technical problem of providing a profile measuring rod mechanism which can greatly reduce errors caused by bearing play and does not lose measurement resolution in the same structural space.

In order to solve the technical problems, the contour degree measuring rod mechanism comprises a contact pin, a measuring rod, a fulcrum and a displacement sensor, wherein the contact pin is arranged at the front end of the measuring rod, the tail end of the measuring rod is rotatably arranged on the fulcrum, and the displacement sensor is arranged at the middle part of the measuring rod.

As the preferable technical scheme, the distance from the front end of the measuring rod to the mounting point of the displacement sensor is equal to the distance from the mounting point of the displacement sensor to the fulcrum.

As an optimal technical scheme, the displacement sensor is a grating ruler sensor.

By adopting the technical scheme, the utility model has the advantages that the error problem caused by bearing play to high-precision detection equipment with profile degree is discovered and proposed for the first time, the arrangement structure of the traditional measuring rod is innovatively changed, the tail end of the measuring rod is rotatably arranged on a fulcrum, and the displacement sensor is arranged in the middle of the measuring rod, so that the error caused by the bearing play is greatly reduced after the arrangement, and the measurement resolution is not lost in the same structural space.

Drawings

The following drawings are only for purposes of illustration and explanation of the present utility model and are not intended to limit the scope of the utility model. Wherein:

FIG. 1 is a schematic diagram of a conventional profilometer mechanism;

FIG. 2 is an exaggerated schematic illustration of bearing play at a fulcrum;

FIG. 3 is a schematic diagram of the effect of bearing play on measurement error at C in a conventional scheme;

FIG. 4 is a schematic diagram showing a front view of the contour measuring bar mechanism in the present embodiment;

FIG. 5 is a schematic top view of the contour measuring bar mechanism in the present embodiment;

Fig. 6 is a schematic diagram showing the influence of the bearing play on the measurement error at C in the present embodiment.

Detailed Description

The utility model is further illustrated in the following, in conjunction with the accompanying drawings and examples. In the following detailed description, certain exemplary embodiments of the present utility model are described by way of illustration only. It is needless to say that the person skilled in the art realizes that the described embodiments may be modified in various different ways without departing from the spirit and scope of the utility model. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive in scope.

As shown in fig. 4 and 5, the profile measuring rod mechanism comprises a contact pin 1, a measuring rod 2, a fulcrum 3 and a displacement sensor 4, wherein the displacement sensor 4 is preferably a grating ruler sensor, the contact pin 1 is arranged at the front end of the measuring rod 2, the tail end of the measuring rod 2 is rotatably arranged on the fulcrum 3, and the displacement sensor 4 is arranged in the middle of the measuring rod 3. In this embodiment, the distance H1 from the front end (a) of the measuring rod 2 to the mounting point (C) of the displacement sensor 4 is equal to the distance H2 from the mounting point (C) of the displacement sensor 4 to the fulcrum 3 (B).

Similarly, the ball bearing is used as the center of rotation at the fulcrum 3, the bearing play, that is, the radial gap existing between the inner and outer rings of the bearing is X, and during the measurement, the contact surface of the stylus 1 at the start point is assumed to be in a horizontal state, and the stylus 1 at the end point is assumed to be in a state as shown in fig. 6. This breaks the movement of the stylus into two parts, the first part being rotation of the stylus about the theoretical centre and the second part being rotation of the stylus about the tip to the condition of figure 6. The first part moves linearly without error, the second part is that the measuring rod generates X-size error at the point A, and the nonlinear error generated by the measuring rod at the point C (namely the position of the displacement sensor) is 1/2*X because the distance H1 is equal to the distance H2. It follows that this arrangement enables errors caused by bearing play to be significantly reduced.

Furthermore, this arrangement makes it possible to measure the resolution without loss in the same installation space. For example, assuming a design vertical scale of 50mm for point A, the effective measurement range for the C-terminal is 25mm for the prior art conventional scheme of FIG. 1 where the AB segment length is twice the BC segment length. In this scheme, the AC segment length H1 is equal to the BC segment length H2, and the effective measurement range of the C end is 25mm as well, that is, the measurement resolution is not lost in the same structural space.

In conclusion, through the innovation change the arrangement structure of traditional measuring staff, the tail end of measuring staff is rotated and is installed on the fulcrum, and install displacement sensor in the middle part of measuring staff, can make the error that the bearing play caused reduce by a wide margin after setting up like this to do not lose the measurement resolution in the same structural space.

The foregoing is illustrative of the present utility model and is not to be construed as limiting the scope of the utility model. Any equivalent changes and modifications can be made by those skilled in the art without departing from the spirit and principles of this utility model, and are intended to be within the scope of this utility model.

Claims

1. The profile measuring rod mechanism comprises a contact pin, a measuring rod, a fulcrum and a displacement sensor, wherein the contact pin is arranged at the front end of the measuring rod.

2. The profilometer stem mechanism of claim 1 wherein the distance from the front end of the stem to the displacement sensor mounting point is equal to the distance from the displacement sensor mounting point to the fulcrum.

3. The profilometer stem mechanism of claim 1 or 2, wherein the displacement sensor is a grating scale sensor.