Magnetic attraction grating ruler, displacement sensor and grating ruler mounting structure

Abstract

This invention discloses a magnetic grating ruler, a displacement sensor, and a grating ruler mounting structure. The grating ruler body integrates magnetic elements, and the magnetic grating ruler is magnetically attached to a machine tool. The grating strip has alternating metal segments and grids arranged along its length. The sensing head integrates two induction coils. When current is applied to the induction coils, a mutual electromotive force is generated between them. The advantages are: the grating strip and the induction coils in the sensing head cooperate to achieve displacement measurement; during use, it can be directly magnetically attached to the equipment using the attraction of the magnetic elements, making installation convenient. Based on this mounting method, the high-precision plane of the machine tool itself can be utilized to make the sensor surface parallel to the high-precision plane of the machine tool, thereby improving the installation accuracy of the grating ruler and ensuring the displacement sensing accuracy of the sensing head.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and specifically to a magnetic grating ruler. Background Technology

[0002] A displacement sensor is a device used to measure and record the distance moved by a moving part. Its working principle is mainly based on converting mechanical displacement into electrical signals or other forms of information output to meet the requirements of information transmission, processing, storage, display, recording and control.

[0003] At the physical structure level, a displacement sensor typically consists of a grating and a sensing head. After being installed on the machine tool under test, the sensing head can reciprocate relative to the length of the grating. Depending on the measurement principle, the grating can be a capacitive grating, optical grating, inductive grating, magnetic grating, etc.

[0004] In existing technologies, grid rulers are generally fixed to machine tool equipment by threaded fasteners. Before installation, tapping and drilling are required, which is a relatively complicated process. Furthermore, there may be processing and assembly errors during drilling and thread tightening, which reduces the installation accuracy of the grid ruler and makes it impossible to guarantee the displacement sensing accuracy of the sensor head. Summary of the Invention

[0005] In view of this, the present invention provides a magnetic grating ruler to solve the technical problems mentioned in the background art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A magnetic ruler includes a ruler body, the key feature of which is that a magnetic element is integrated on the ruler body, the magnetic element being used to magnetically fix the ruler body to the device.

[0008] Preferably, the magnetic element is a magnet block, and the number of the magnet blocks is at least two, with each magnet block arranged in an array along the length of the grid ruler body.

[0009] Preferably, the grid ruler body includes a grid strip and a base. The base has an elongated strip structure with a strip groove on its upper side. Each of the magnet blocks is distributed on the bottom of the strip groove, and the grid strip is installed along the length of the strip groove.

[0010] Preferably, a pad is installed in the strip groove, the magnet block is embedded in the pad, and the grid strip is installed on the upper side of the pad.

[0011] Preferably, the magnetic element is a magnetic strip integrated within the grating body.

[0012] Preferably, the grid ruler body includes a grid strip, and the spacing between the magnetic strip and the grid strip is greater than 1.5 mm.

[0013] Preferably, a magnetic shielding sheet is provided between the magnetic element and the grid strip.

[0014] Preferably, the grid strip array along its length is provided with alternating metal segments and grids, the grids being used in conjunction with the induction coil for displacement calculation.

[0015] Preferably, the grid strip includes a PCB board, and the metal segment is formed by printing metal foil on the PCB board; or, the grid strip is a metal strip, and the grid is a through hole or groove provided on the metal strip.

[0016] Preferably, the grating body is an optical grating, a capacitive grating, or a magnetic grating.

[0017] Preferably, the bottom of the ruler body is provided with double-sided adhesive.

[0018] This utility model also provides a displacement sensor, the key feature of which is: it includes a sensing head and the magnetic grid ruler. After the magnetic grid ruler and the sensing head are installed on the device under test, the sensing head can move relative to the length direction of the magnetic grid ruler.

[0019] The induction head is provided with at least two induction coils. When current is passed through the induction coils, mutual electromotive force can be generated between the induction coils.

[0020] As the sensing head moves along the length of the magnetic grid ruler, the mutual electromotive force between the various sensing coils changes according to the arrangement of the grid.

[0021] This utility model also provides a grid ruler installation structure, the key of which is: it includes a machine tool and the magnetic grid ruler, which is attached and fixed to the machine tool by magnetic elements.

[0022] Preferably, one end of the magnetic grid ruler is fixedly connected to the machine tool equipment by riveting or threaded fasteners.

[0023] This utility model also provides that the machine tool bed is an aluminum component with iron strips fixed on its surface, and the magnetic grid ruler is adsorbed and fixed on the iron strips.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. The magnetic grating ruler provided by this invention can be directly magnetically attached to the equipment using the magnetic force of the magnetic element, making installation convenient. Based on this installation method, the high-precision plane of the machine tool itself can be utilized to make the sensor surface parallel to the high-precision plane of the machine tool, thereby improving the installation accuracy of the grating ruler and ensuring the displacement sensing accuracy of the sensing head.

[0026] 2. By using the magnetic grid ruler provided by this invention, the magnet block is held in a certain position by the padding layer, and a mounting base surface is provided for the grid strip above, which can form a compact grid ruler product.

[0027] 3. The magnetic grid ruler provided by this invention has magnetic blocks arranged in an array along the length of the grid ruler body, resulting in uniform magnetic force distribution, which helps to improve installation stability.

[0028] 4. The displacement sensor provided by this invention measures displacement by observing the change in the mutual inductance between the grating and the coil, offering a novel displacement sensing and measurement method with extremely high measurement accuracy. The inductive grating can achieve a resolution of up to 20nm, which is a crucial element for high-quality motion control applications, such as micro-motion platforms. The inductive sensor has low output noise and high output signal quality, resulting in an excellent overall signal-to-noise ratio. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the magnetic grating ruler A.

[0030] Figure 2 This is a cross-sectional view of magnetic grating ruler A.

[0031] Figure 3 This is an exploded diagram of magnetic grating ruler A.

[0032] Figure 4 This is a schematic diagram of a displacement sensor that measures displacement based on the variation law of mutual inductance electromotive force of multiple coils.

[0033] Figure 5 This is another structural schematic diagram of the magnetic grating ruler A.

[0034] Figure 6 This is a schematic diagram of the installation of the magnetic grating ruler A in a machine tool. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0036] like Figure 6 As shown, a grid ruler mounting structure includes a machine tool C and a magnetic grid ruler A, wherein, combined with Figure 1 and 2As can be seen, the magnetic scale A integrates a magnetic element 2 on its scale body, and the magnetic scale A is attracted and fixed to the machine tool C by the magnetic element 2. The magnetic installation method is not only convenient to install, but also utilizes the flatness of the machine tool C itself to tightly fit the scale body onto it, conforming to the changes in the flatness of the machine tool surface. This avoids the situation where the long strip scale body arches or sinks in the middle after installation, thus greatly improving the installation accuracy of the scale and the displacement sensing accuracy.

[0037] Furthermore, one end of the magnetic grating ruler A can be fixedly connected to the machine tool equipment via riveting or threaded fasteners, and then... Figure 6 The left end of the magnetic grating ruler A is fixedly connected to the machine tool equipment by the threaded fastener 10. This fixes one end of the magnetic grating ruler A, while the other end can freely expand and contract with temperature changes. This makes the coefficient of thermal expansion and contraction of the grating strip 1 of the ruler body unrestricted, which is more conducive to obtaining high-precision data under various temperature conditions.

[0038] Furthermore, the bottom of the scale body is equipped with double-sided adhesive. When installing the magnetic scale A, simply peel off the double-sided adhesive and the scale can be accurately attached to the machine tool bed. With the combined effect of the double-sided adhesive and the magnetic attraction, it can be firmly attached for a long time. It is easy to use and can be used immediately after application.

[0039] For machine tool beds made of aluminum or stainless steel, which lack magnetic attraction, a layer of iron or 430 stainless steel strip can be installed on the surface of the bed substrate first. This not only helps to roughly determine the installation position of the magnetic ruler A but also makes installation easier. Finally, the magnetic ruler A is attached to the iron or 430 stainless steel strip to complete the installation.

[0040] In the magnetic grating ruler A, the magnetic element 2 is a magnetic block or a magnetic strip.

[0041] Please refer to the attached document. Figure 2 and 3 As shown, when the magnetic element 2 is a magnet block, there are at least two of them, and each magnet block is arranged in an array along the length of the grid ruler body. The magnetic grid ruler A includes a grid strip 1 and a long strip-shaped base 4. The base 4 has a strip groove 4a on its upper side, and each magnet block is distributed on the bottom of the strip groove 4a. The grid strip 1 is installed along the length of the strip groove 4a. Distributing the magnet blocks along the length of the base 4 results in a uniform magnetic force distribution, which helps to improve installation stability. Furthermore, a pad layer 5 is installed in the strip groove 4a, and the grid strip 1 is located on the upper side of the pad layer 5. The magnet blocks are embedded in the pad layer 5. With this design, the pad layer 5 can limit the magnets to a certain position and provide a mounting base surface for the grid strip above, thereby forming a grid ruler product with a compact structure and high magnet block stability.

[0042] Please refer to the attached document. Figure 5As shown, when the magnetic element 2 is a magnetic strip, it is integrated into the grid body along its length. Because the magnetic strip is conductive, it will interfere with the inductor coil when used in an inductive grid sensor. Therefore, a sufficient distance, preferably greater than 1.5 mm, is required between the magnetic strip and the grid strip 1. In addition, a magnetic shielding sheet 9 can be spaced between the magnetic element 2 and the grid strip to weaken the front magnetic field and reduce its influence on the outside world. This method can also reduce the impact on the induction coil.

[0043] The scale body in the magnetic scale A can be an optical scale, a capacitive scale, an inductive scale, or a magnetic scale. Among them, the application of optical scales, capacitive scales, and magnetic scales are mature technologies, and their structures will not be described in detail here.

[0044] The following further discloses an inductive grating ruler, whose measurement principle is based on the change of mutual inductance electromotive force of multiple coils to measure displacement. It can break through the measurement limits of traditional sensors and has significant advantages in terms of accuracy and measurement precision.

[0045] like Figure 4 As shown, a displacement sensor based on the change of mutual inductance electromotive force of multiple coils mainly involves two parts: a sensing head B and a magnetic grating ruler A. After the magnetic grating ruler A and the sensing head B are installed in the device under test, the sensing head B is arranged on one side of the magnetic grating ruler A and can move relative to the length direction of the magnetic grating ruler A. (See attached diagram.) Figure 1 As can be seen, the grid strip 1 of the magnetic grid ruler A is a long strip-shaped sheet structure, with alternating metal segments 1b and grids 1a arranged along its length. The induction head B contains two induction coils. In this embodiment, the two induction coils are a main coil 6 and a secondary coil 7, with the secondary coil 7 being a sinusoidal coil located within the main coil 6. When an oscillating current is applied to the main coil 6, a mutual induced electromotive force is generated between the main coil 6 and the secondary coil 7.

[0046] Based on the above structure, in practical applications, the magnetic grid ruler A is fixedly installed in the device under test, while the sensing head B is slidably installed within the device, ensuring that the induction coil inside the sensing head B faces the side of the grid strip 1. During operation, after an oscillating current is applied to the main coil 6, as the sensing head B reciprocates relative to the magnetic grid ruler A, the main and secondary coils have a mutual induced electromotive force (EMF) at the grid 1 position. The remaining mutual EMF is shielded by the metal segment 1b. Since the secondary coil 7 is a sinusoidal coil, the mutual EMF between the main and secondary coils also exhibits a sinusoidal change as the sensing head B moves relative to the grid 1a. That is, the mutual EMF changes with the displacement of the grid 1a. Therefore, as the sensing head B moves along the length of the grid strip 1, the displacement of the sensing head B can be obtained by calculating the displacement based on the change in mutual EMF, thus achieving displacement measurement of the target product.

[0047] like Figure 1 As shown, the main body of the grid strip 1 is a PCB board, and the metal segments 1b are formed by printing metal foil on the PCB board. A grid 1a is formed between two adjacent metal segments 1b. Alternatively, the grid strip 1 can be a single metal strip, and the grid 1a can be a through hole or groove set on the metal strip.

[0048] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention. Those skilled in the art, under the guidance of the present invention, can make various similar representations without departing from the spirit and claims of the present invention, and such modifications all fall within the protection scope of the present invention.

Claims

1. A magnetic grating ruler (A), comprising a grating ruler body, characterized in that: The grid ruler body is integrated with a magnetic element (2), which is used to magnetically fix the grid ruler body to the device; The scale body has a grid strip (1), and the grid strip (1) is arranged in a longitudinal direction with alternating metal segments (1b) and grids (1a). The grids (1a) are used to cooperate with the induction coil for displacement calculation.

2. The magnetic grating ruler according to claim 1, characterized in that: The magnetic element (2) is a magnet block, and there are at least two of them. Each of the magnet blocks is arranged in an array along the length of the grid body.

3. The magnetic grating ruler according to claim 2, characterized in that: The grid ruler body also includes a base (4), which has a long strip structure and a strip groove (4a) on its upper side. Each of the magnet blocks is distributed on the bottom of the strip groove (4a), and the grid strip (1) is installed along the length direction of the strip groove (4a).

4. The magnetic grating ruler according to claim 3, characterized in that: A pad (5) is installed in the strip groove (4a), the magnet block is embedded in the pad (5), and the grid strip (1) is installed on the upper side of the pad (5).

5. The magnetic grating ruler according to claim 1, characterized in that: The magnetic element (2) is a magnetic strip integrated into the grating body.

6. The magnetic grating ruler according to claim 5, characterized in that: The grating body includes a grating strip (1), and the distance between the magnetic strip and the grating strip (1) is greater than 1.5 mm.

7. The magnetic grating ruler according to claim 3, 4, or 6, characterized in that: A magnetic shielding sheet (9) is provided between the magnetic element (2) and the grid strip (1).

8. The magnetic grating ruler according to claim 1, characterized in that: The grid strip (1) includes a PCB board, and the metal segment (1b) is formed by printing metal foil on the PCB board; Alternatively, the grid strip (1) may be a metal strip, and the grid (1a) may be a through hole or groove provided on the metal strip.

9. The magnetic grating ruler according to claim 1, characterized in that: The grating ruler body is an optical grating ruler, a capacitive grating ruler, or a magnetic grating ruler.

10. The magnetic grating ruler according to claim 1, characterized in that: The bottom of the ruler body is provided with double-sided adhesive.

11. A displacement sensor, characterized in that: The device includes a sensing head (B) and a magnetic grating ruler (A) as described in claim 1. After the magnetic grating ruler (A) and the sensing head (B) are installed on the device under test, the sensing head (B) can move relative to the length direction of the magnetic grating ruler (A). The sensing head (B) is provided with at least two induction coils (a). When current is passed through the induction coils (a), mutual electromotive force can be generated between the induction coils (a). As the sensing head (B) moves along the length of the magnetic grid ruler (A), the mutual inductance electromotive force between each of the sensing coils (a) changes according to the arrangement of the grid (1a).

12. A grid ruler mounting structure, characterized in that: The invention includes machine tool equipment and a magnetic grid ruler (A) according to any one of claims 1 to 10, wherein the magnetic grid ruler (A) is attracted and fixed to the machine tool equipment by a magnetic element (2).

13. The grid ruler mounting structure according to claim 12, characterized in that: One end of the magnetic grating ruler (A) is fixedly connected to the machine tool equipment by riveting or threaded fasteners.

14. The grid ruler mounting structure according to claim 12, characterized in that: The machine tool bed is made of aluminum, and iron strips or 430 stainless steel strips are fixed on its surface. The magnetic grid ruler (A) is adsorbed and fixed on the iron strips or 430 stainless steel strips.

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