JP2012002554A - Three dimensional load cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three dimensional load cell with enhanced accuracy and high practicality in load measurement.SOLUTION: A three dimensional load cell 10 comprises: a base 12; a load receiving portion 14 supported being interposed by a gap G between the base 12 and the same; a first, second and third strain portions 161, 162 and 163 constituted of plural strain portions each formed in a bridge-like shape between the base 14 and the load receiving portion 14, which are oriented in three directions; i.e. in an arbitral first direction, a second direction crossing the first direction, and a third direction crossing a plane including the first direction and the second direction, one end of which is fixed to the base 12 and the other end thereof is fixed to the load receiving portion 14 to support the load receiving portion 14 on the base 12, and when a load is applied, the load receiving portion 14 strains; and strain gauges each attached to the first, second and third strain portions.

Description

  The present invention relates to a three-dimensional load cell capable of measuring the magnitude of a load, its direction, and the component force of a three-dimensional component in three directions.

  A load cell is a load measuring device that measures the load using a relationship between the stress applied to the elastic body and the output from the strain gauge by attaching a strain gauge to the elastic body, and conventionally measures the load in one direction. The ones designed in this way are popular. The load cell has a simple structure, can be manufactured at low cost, and has relatively high measurement performance, responsiveness, and reliability. Therefore, the load cell is used for measuring instruments such as scales and balances.

  For example, as disclosed in Patent Document 1, the load cell is also used in a wheel acting force measuring device that measures an acting force on a ground contact portion of a wheel of an automobile or a two-wheeled vehicle. In Patent Document 1, four arm portions 10, 10... Extending in a cross shape outwardly along the X-axis and Y-axis directions from the base portion 9 extending in the Z-axis direction, which is the rotation axis direction of the wheel, are provided. The technology of a multi-force load cell in which strain gauges 18, 18... Are attached to the four arm portions 10, 10. Based on the strain detection values by the strain gauges 18, 18... Attached to the four arms, the component forces Fx, Fy, Fz in the X, Y, and Z axial directions and the couple Mx around each axis, The six component forces of My and Mz were measured. In addition, a code | symbol is a thing of patent document 1.

Japanese Patent Laid-Open No. 11-173929

  Although the load cell is widely used in various fields as described above, there are many scenes in which it is necessary to measure a load applied in an arbitrary direction as in three dimensions. However, since the conventional load cell can measure only one direction, it is necessary to install a plurality of load cells along each direction to be measured in order to measure the load. Therefore, since the load cells measure the load independently, there is a problem that the accuracy is inferior in measuring the three-dimensional load and its component force, and the mounting position is restricted. The multi-component load cell described in Patent Document 1 has a configuration applied to a wheel, but the arm portion to which the strain gauge is attached is arranged in a cross shape along the X-axis direction and the Y-axis direction. Since the arm portion is not arranged in the Z-axis direction, the arrangement is a two-dimensional arrangement, and therefore there is a possibility that the accuracy is inferior in measuring a three-dimensional load.

  On the other hand, when a part is manufactured by plastic deformation of a material in forging, a highly accurate product that does not have seizure or scratches on its surface is required, and therefore the use of a lubricant is indispensable. In the plastic deformation process of the material, it is important to evaluate the friction of the material surface by measuring the friction coefficient and to evaluate the performance of the lubricant. However, the material is often plastically deformed three-dimensionally, and as a result of the high temperature and high surface pressure during the deformation process, the environment of the friction surface of the material becomes complicated and it is difficult to measure the accurate friction coefficient. there were. Therefore, development of a technique for measuring an accurate friction coefficient has been desired.

  The present invention has been made in view of the above-described conventional problems, and one object of the present invention is to simultaneously measure the magnitude of the load, its direction, and the component force in three directions, improving the measurement accuracy and being practical. The object is to provide a high three-dimensional load cell. Another object of the present invention is to provide a three-dimensional load cell that can be satisfactorily applied to a drawing process, a friction tester, and the like and can realize a highly accurate load measurement in order to accurately measure and calculate a friction coefficient of a material. .

  In order to solve the above problems, the present invention provides a base 12, a load receiving portion 14 that is supported with a gap G between the base 12, one end fixed to the base 12, and the other end to the load receiving portion 14. A plurality of strain generating portions that are fixed to support the load receiving portion 14 on the base portion 12 and cause distortion when the load receiving portion 14 receives a load, and intersects the first direction with an arbitrary first direction. The first, which is provided between the base portion 14 and the load receiving portion 14 so as to extend in the three directions of two directions and a third direction intersecting a plane including the first direction and the second direction, A three-dimensional structure including second and third strain generating portions 161, 162, and 163 and strain gauges 18 attached to the first, second, and third strain generating portions 161, 162, and 163, respectively. The load cell 10 is configured.

  In addition, the first, second, and third strain generating portions 161, 162, and 163 are provided in a spanning manner between the load receiving portion 14 and the base portion 12 along three axial directions orthogonal to each other. Also good.

  The three-dimensional load cell is a load cell that measures a load acting on a die in a drawing process in which the material M is drawn and passed through a die while linearly moving, and the material is plastically processed into a desired shape. And a die attaching portion (22) for attaching the die, and the first strain generating portion 161 is provided along the first axis (x-axis) direction parallel to the linear movement direction L of the material, and the second strain generating portion. 162 is provided along a second axis (y-axis) direction orthogonal to the first axis direction, and the third strain generating portion 163 is a third axis orthogonal to both the first axis direction and the second axis direction. It may be provided along the (z-axis) direction. For example, the present invention may be applied when a product is actually manufactured by performing a drawing process, or may be applied to a material testing machine using a drawing process.

  The base 12 is provided in a partially cut-out box shape in which one corner is notched and recessed, and the load receiving portion 14 is installed at the notch recessed position (22) of the base 12. It is good.

  Further, the base portion 12, the load receiving portion 14, and the first, second, and third strain generating portions 161, 162, and 163 may be integrally formed. For example, it may be integrally formed by machining from a metal material, or by molding molten metal or molten synthetic resin into a mold.

  According to the three-dimensional load cell of the present invention, the load receiving portion supported with a gap between the base portion and the base portion, one end fixed to the base portion and the other end fixed to the load receiving portion, A plurality of strain generating portions that are supported by the base and generate strain when the load receiving portion receives a load, an arbitrary first direction, a second direction that intersects the first direction, a first direction, and a second direction First, second, and third strain-generating portions provided in a bridge shape between the base portion and the load receiving portion in the three directions of the third direction intersecting the plane including the direction, and the first direction And the strain gauges attached to the second and third strain generating portions, respectively, so that the structure is simple and the first, second, and third strain generating portions are provided in three different directions. Thus, the component force of the three-direction component of the load and the direction in which the load is applied can be accurately measured. In addition, it can be easily attached to a measurement symmetric testing machine or various devices, and can be used in a wide range of applications. In particular, if a three-dimensional load cell is applied to a friction tester or the like, accurate measurement of the friction coefficient can be realized, and the performance and reliability of the material test can be improved.

  In addition, the first, second, and third strain generating portions are configured to be provided between the load receiving portion and the base portion along three axial directions orthogonal to each other, so that the measurement target is The load component in the x-axis, y-axis, and z-axis directions can be measured smoothly and accurately with high accuracy, and load analysis can be easily performed.

  The three-dimensional load cell is a three-dimensional load cell that measures a load acting on the die in a drawing process in which the material is drawn and passed through a die while linearly moving, and the material is plastically processed into a desired shape. And a die attaching portion for attaching the die, wherein the first strain generating portion is provided along a first axial direction parallel to the linear movement direction of the material, and the second strain generating portion is orthogonal to the first axial direction. The third strain generating portion is provided along the third axis direction that is orthogonal to both the first axis direction and the second axis direction. By specifically assembling a three-dimensional load cell on a die such as the like, it is possible to accurately measure the component forces in three orthogonal directions, and to analyze the load acting on the die. Furthermore, the coefficient of friction between the material and the die can be accurately measured, and the friction characteristics of the material surface and the performance evaluation of the lubricant can be performed smoothly and accurately.

  Also, the base is provided in a partially cut-out box shape in which one corner is cut and recessed, and the load receiving portion is arranged by being installed at the notch and recessed position of the base. An efficient structure can be specifically realized, and can be efficiently installed on a drawing machine or other load measuring object.

  In addition, by adopting a configuration in which the load receiving portion, the base portion, and the first, second, and third strain generating portions are integrally formed, there is a problem such that an error occurs due to absorption of a load at a connection portion between the components. It is possible to prevent the load measurement with high accuracy.

It is a perspective view of the three-dimensional load cell concerning one embodiment of the present invention. It is a top view of the three-dimensional load cell of FIG. It is a front view of the three-dimensional load cell of FIG. It is a side view of the three-dimensional load cell of FIG. It is explanatory drawing which shows the example which performed the load measurement test by a three-dimensional load cell. It is a graph of the result of the load measurement test of the three-dimensional load cell which concerns on the Example of this invention. It is a perspective view of other embodiments of a three-dimensional load cell. It is a top view explaining the example which attached the three-dimensional load cell of FIG. 1 to the drawing-type friction tester. It is principal part perspective explanatory drawing of the die periphery of the friction tester of FIG. FIG. 10 is a plan view of FIG. 9. FIG. 10 is a side view of FIG. 9.

  Hereinafter, an embodiment of a three-dimensional load cell of the present invention will be described with reference to the accompanying drawings. The three-dimensional load cell according to the present invention is a load measuring device advantageous for three-dimensional load measurement. 1 to 4 show an embodiment of the three-dimensional load cell of the present invention. In the present embodiment, as shown in FIG. 1, the three-dimensional load cell 10 is attached to a base 12, a load receiving portion 14 that receives a load, a plurality of strain generating portions 16, and a plurality of strain generating portions 16. Strain gauge 18.

  The base portion 12 is a base body that has a certain degree of rigidity and supports the load receiving portion 14 and the strain-generating portion 16 by being assembled together. The base portion 12 is a fixed portion for the load receiving portion 14 that receives a load, and has a strength that does not easily deform when the load is transmitted from the load receiving portion 14 to the strain generating portion 16. In this embodiment, as shown in FIGS. 1, 2, 3, and 4, the base portion 12 is made of a metal such as carbon steel and has a certain size in the vertical direction, the horizontal direction, and the height direction. It consists of a solid block body formed of The base portion 12 is provided in a partially cut-out box shape in which, for example, one corner portion of a substantially three-dimensional rectangular box shape is cut out to form a concave portion 20. The direction along the horizontal side of the base 12 in plan view is the x-axis direction, the direction along the vertical side of the base 12 orthogonal to the x-axis direction in plan view is the y-axis direction, and the vertical height direction in front view, The direction orthogonal to the plane including the x axis and the y axis is taken as the z axis direction. The concave portion 20 of the base 12 is formed with, for example, three concave side surfaces 201 to 203 that are parallel to the xy plane, the yz plane, and the xz plane, and these three concave side surfaces 201 to 203 are connected to the load receiving portion 14. Opposite. The base 12 may have any shape as long as it can support the load receiving portion 14 and the strain-generating portion 16. Further, the base portion 12 is a convex portion that engages with a component member on the other device side in order to enable the load cell to be attached to another device such as a drawing machine or a material testing machine as shown in FIG. A portion, a recess, a notch, a hole, a fixing bolt hole, or the like may be provided.

  As shown in FIGS. 1, 2, 3, and 4, the load receiving unit 14 is a load receiving unit that receives a load by directly or indirectly engaging a measurement object, and a gap between the load receiving unit 14 and the base 12. G is supported. The load receiving portion 14 is supported at an aerial position with respect to the base portion 12 by a plurality of strain generating portions 16 extending in three directions like legs from the load receiving portion 14. The load receiving portion 14 is a movable portion that can move slightly when a load is applied to the fixed base 12, and transmits the received load to the plurality of strain generating portions 16. In the present embodiment, the load receiving portion 14 is made of, for example, a metal such as carbon steel, and a portion in which a receiving recess 22 is formed by cutting out one corner of a substantially three-dimensional rectangular box shape. It is provided in a notch box shape. The load receiving portion 14 is disposed in a recessed shape in the recess 20 of the base 12, and the three side surfaces 261 to 263 that are not provided with the receiving recess 22 are exposed to the base 12 while the receiving recess 22 is exposed outward. The inner surfaces of the recesses 201 to 203 are spaced apart from each other in parallel. The receiving recess 22 is, for example, a substantially three-dimensional rectangular recess space, and constitutes a die attaching portion to which a tool such as a die as described later is attached. In addition, the load receiving part 14 is not restricted to a shape like this embodiment, For example, the receiving recessed part 22 does not need to be provided and may be formed in other arbitrary shapes according to a measuring object.

  As shown in FIGS. 1, 2, 3, and 4, the strain generating portion 16 supports one end of the strain receiving portion 16 to the base portion 12 and the other end to the load receiving portion 14 to support the load receiving portion 14 to the base portion 12. It is an elastic body that is a support means and generates distortion when the load receiving portion 14 receives a load. The strain generating portion 16 is a beam interposed in the gap G between the base portion 12 as the fixed portion and the load receiving portion 14 as the movable portion. When a load is transmitted from the load receiving portion 14, the load is large. Strain is generated corresponding to the height, and when the load is released, it returns elastically. Each of the strain generating portions 16 is made of a square columnar arm having a square cross section formed of a metal such as carbon steel. The shape of the strain generating portion 16 is not limited to a quadrangular prism shape, and may be formed in a columnar shape or a plate shape, for example.

  In the present embodiment, the plurality of strain generating portions 16 are provided in a linearly extending manner toward three different axial directions between the base portion 12 and the load receiving portion 14, and are in the first direction x A first straining portion 161 (beam) provided in the axial direction, a second straining portion 162 (beam) provided in the y-axis direction that is the second direction, and z that is in the third direction And a third strain generating portion 163 (beam) provided in the axial direction. The first, second, and third strain generating portions 161 to 163 are provided one by one in the directions of three axes (x-axis, y-axis, and z-axis) that are orthogonal to each other, and the total number of strain generating portions is three. It is the structure which was provided. For example, the first, second, and third strain generating portions 161 to 163 are integrally connected to the concave side surfaces 201 to 203 of the base portion 12 as the first to third beams, respectively, and the other end of the load receiving portion 14. The side surfaces 261 to 263 are integrally connected, and are provided orthogonal to the facing surfaces of the base portion 12 and the load receiving portion 14. The first, second, and third strain generating portions 161 to 163 extending in three orthogonal directions are designed in consideration of mutual interference in each direction, and have a small error, and the x-axis and y-axis of the load. The arrangement configuration of the strain generating portion that can easily and accurately measure the component force in the three-dimensional direction of the z-axis is realized. Since the first, second, and third strain generating portions 161, 162, and 163 are three-dimensionally provided in three orthogonal directions as described above, component forces in the x-axis, y-axis, and z-axis directions are provided. Measurement accuracy can be improved, and it is highly practical as a load cell for three-dimensional load measurement.

  In the present embodiment, the load cell body including the base portion 12, the load receiving portion 14, and the first, second, and third strain generating portions 161, 162, and 163, for example, cuts a steel ingot into a predetermined shape as described above. Processed and integrally formed. As a result, the three-dimensional load cell 10 has an integrated structure with no connecting members such as joints and screws between the components, and when receiving a load, the load is absorbed by the influence of the joints and connecting members to improve measurement accuracy. It is possible to prevent the reduction, and high measurement accuracy can be obtained. The material of the load cell body may be formed of, for example, rubber, plastic, aluminum, iron, other alloys, etc., and may be appropriately selected depending on the magnitude of the load to be measured. The three-dimensional load cell 10 is manufactured by configuring the base portion 12, the load receiving portion 14, the first, second, and third strain generating portions 161, 162, and 163 as separate members and connecting them to a predetermined structure. However, it is possible to obtain higher measurement accuracy with the structure integrally formed as described above.

  As shown in FIGS. 1, 2, 3, and 4, the strain gauge 18 is attached to each of the strain generating portions 161, 162, and 163, and an electric power is generated according to the strain generated in the strain generating portions. This is a strain detection sensor whose resistance changes. As the strain gauge 18, for example, a conventionally known strain gauge using a resistance wire or a metal foil is used, and one or a plurality of strain gauges 161, 162, and 163 are attached to each of the strain generating portions 161, 162, and 163. The strain gauge 18 is electrically connected to the bridge circuit 24. As the bridge circuit 24, for example, a well-known conventional bridge circuit is used, and a change in electrical resistance of the strain gauge 18 is converted into a voltage change and output. The bridge circuit 24 may be connected to, for example, an amplifier device that amplifies the circuit output, a monitor device that displays the output numerically, a recorder device that records the numerical value, and the like.

第１、第２、第３起歪部１６１、１６２、１６３は全て荷重受部１４に一体的に固定されているので、各方向の起歪部１６１、１６２、１６３どうしが互いに影響を及ぼすようになっている。なお、Ａｘ、Ａｙ、Ａｚ、Ｂｘ、Ｂｙ、Ｂｚ、Ｃｘ、Ｃｙ、Ｃｚは起歪部の形状や構成、ブリッジ回路等を含む諸条件により定まるパラメータである。そして、荷重Ｐは各分力Ｐｘ、Ｐｙ、Ｐｚの合力として、次の計算式で求められる。

或いは、合力Ｐは下記の式からも求められる。

さらに、荷重Ｐのｘ軸、ｙ軸、ｚ軸方向に対する角度θｘ、θｙ、θｚとすると、方向余弦及び、各角度θｘ、θｙ、θｚは次の計算式で求められる。

Therefore, in the three-dimensional load cell 10, when the load receiving portion 14 receives a load, strain corresponding to the load is generated in each strain generating portion 16, and is converted into a change in electric resistance by the strain gauge 18 according to the strain, The change in the electrical resistance is converted into a voltage change by the bridge circuit 24, a predetermined calculation is performed according to the output voltage, and the load P applied to the load cell and the component forces Px in the x-axis, y-axis, and z-axis directions, Py and Pz are obtained. In the present embodiment, for example, the output value εx of the circuit from the first strain gauge 18 attached to the first strain-generating part 161 in the x-axis direction, the second attached to the second strain-generating part 162 in the y-axis direction. Assuming that the output value εy of the circuit from the strain gauge 18 and the output value εz of the circuit from the third strain gauge 18 attached to the third strain generating portion 163 in the z-axis direction, the load P applied to the three-dimensional load cell 10 The component force Px in the x-axis direction, the component force Py in the y-axis direction of the load P, and the component force Pz in the z-axis direction of the load P are approximately obtained by the following calculation formulas, respectively.

Since the first, second, and third strain generating portions 161, 162, and 163 are all fixed integrally to the load receiving portion 14, the strain generating portions 161, 162, and 163 in each direction affect each other. It has become. Ax, Ay, Az, Bx, By, Bz, Cx, Cy, and Cz are parameters determined by various conditions including the shape and configuration of the strain generating portion, the bridge circuit, and the like. And the load P is calculated | required with the following formula as a resultant force of each component force Px, Py, and Pz.

Alternatively, the resultant force P can be obtained from the following equation.

Furthermore, when the angles θx, θy, and θz of the load P with respect to the x-axis, y-axis, and z-axis directions are given, the direction cosine and the angles θx, θy, and θz can be obtained by the following calculation formulas.

これらの係数を［数１］の計算式に代入すると、ひずみεx、εy、εzと分力Ｐｘ、Ｐｙ、Ｐｚとの関係式は次の計算式となる。

上記計算式の確認のために、図５に示すように、３次元ロードセル１０を水平方向に対して、例えば、φｘ＝４５度、φｙ＝φｚ＝３０度傾けて鉛直方向に荷重Ｐ_０を加えて実験を行った。すなわち、３次元ロードセル１０に、θｘ＝４５°、θｙ＝６０°、θｚ＝６０°の方向に向けて荷重Ｐ_０を加えた。理論計算結果と上式から算出される分力および合力を比較した。図６はその比較した結果を示す。図６のグラフの横軸は本実施形態に係る３次元ロードセルに実際に加えた荷重Ｐ_０（重量トン（ｔｆ：ton-force））、縦軸が３次元ロードセル１０が出力した各軸方向の分力Ｐｘ、Ｐｙ、Ｐｚ及び合力荷重Ｐ（重量トン（ｔｆ：ton-force））の結果である。なお、一例として、３次元ロードセルに、荷重Ｐ_０＝０．７９ｔをθｘ＝４５°、θｙ＝６０°、θｚ＝６０°の方向に加えると［表１］の結果となった。

図６に示すように、実線で表した出力理想値に対してロードセル１０の出力結果の誤差が少なく、高い測定精度を期待できる。これにより、本実施形態では［数７］の計算式を利用して３次元ロードセルに任意に加えた荷重の分力、合力、方向等を得ることができる。 In the present embodiment, the relational expressions of the respective strains εx, εy, εz and the component forces Px, Py, Pz of the first to third strain generating portions (first to third beams) 161 to 163 are expressed by 1], the load test (compression test) is performed on each of the x-axis, y-axis, and z-axis to obtain data on the component forces Px, Py, and Pz. From the above, the coefficient was obtained by the method of least squares.

By substituting these coefficients into the formula of [Equation 1], the relational expression between the strains εx, εy, εz and the component forces Px, Py, Pz becomes the following formula.

In order to confirm the above calculation formula, as shown in FIG. 5, the load P ₀ is applied in the vertical direction by tilting the three-dimensional load cell 10 with respect to the horizontal direction, for example, φx = 45 degrees and φy = φz = 30 degrees. The experiment was conducted. That is, the load P ₀ was applied to the three-dimensional load cell 10 in the directions of θx = 45 °, θy = 60 °, and θz = 60 °. The component force and resultant force calculated from the theoretical calculation result and the above equation were compared. FIG. 6 shows the comparison result. The horizontal axis of the graph of FIG. 6 is the load P ₀ (ton ton (tf)) actually applied to the three-dimensional load cell according to the present embodiment, and the vertical axis is the direction of each axis output by the three-dimensional load cell 10. It is the result of component force Px, Py, Pz and resultant load P (weight ton (tf: ton-force)). As an example, when a load P ₀ = 0.79 t was applied to a three-dimensional load cell in the directions of θx = 45 °, θy = 60 °, and θz = 60 °, the results shown in Table 1 were obtained.

As shown in FIG. 6, there is little error in the output result of the load cell 10 with respect to the ideal output value represented by a solid line, and high measurement accuracy can be expected. Thereby, in the present embodiment, the component force, resultant force, direction, and the like of the load arbitrarily applied to the three-dimensional load cell can be obtained using the formula of [Equation 7].

  The configuration of the three-dimensional load cell 10 is not limited to the above embodiment. For example, a plurality of the first, second, and third strain generating portions 161, 162, and 163 may be provided in the x-axis, y-axis, and z-axis directions. FIG. 7 shows another embodiment 10a of the three-dimensional load cell. As shown in FIG. 7, the plurality of strain generating portions 16 are formed by, for example, one first strain generating portion 161 in the x-axis direction. However, two second strain generating portions 162a and 162b are provided in the y-axis direction, and two third strain generating portions 163a and 163b are provided in the z-axis direction, for a total of five strain generating portions. have. The second strain generating portions 162a and 162b and the second strain generating portions 163a and 163b are arranged in parallel with a predetermined gap therebetween. Each strain generating portion 16 is provided in a substantially rectangular plate shape, for example. Two strain gauges 18 are attached to the front and back surfaces of the substantially rectangular plate-like strain generating portion, and a total of four strain gauges 16 are attached to each strain generating portion 16. In the three-dimensional load cell 10a of this embodiment, the load bearing strength of the strain generating portion can be configured higher than that of the load cell 10 of the above embodiment, which is suitable for measuring a large load of several tons or more, for example. Available. The three-dimensional load cell 10 can be manufactured corresponding to a measurement range of several gf to several thousand tf by changing the constituent conditions such as the material, cross-sectional area, shape, and number of the strain generating portion 16. It is possible to measure a relatively small load of several tens of kilograms by measuring the size of the three-dimensional load cell and the load cell material, and it is also possible to measure a relatively large load of several thousand tf. is there.

  Moreover, the direction of the 1st, 2nd, 3rd strain generation part 161,162,163 is not restricted to the structure provided toward the direction orthogonal to each other. For example, the first strain generating portion 161 is provided in an arbitrary first direction α, the second strain generating portion 162 is provided in a second direction β intersecting at an angle θ that is not orthogonal to the first direction, The three strain generating portions 163 are provided toward a third direction γ that intersects at an angle of φ that is not orthogonal to the plane including the first direction and the second direction, and are not on the same plane and are not parallel to each other. It is good to be provided. That is, the first and second strain generating portions 161 and 162 are provided in different first directions α and second directions β intersecting each other at an angle θ (0 ° <θ <180 °), and the third strain generating portions. The part 163 may be provided toward a third direction γ that intersects the plane including the first direction and the second direction at an angle φ (0 ° <φ <180 °). Even in this case, one strain generating portion may be provided in each direction, or a plurality of strain generating portions may be provided in each direction.

  Next, the case where the load acting on the die is measured using the three-dimensional load cell 10 of the above embodiment in a drawing machine will be described with reference to FIGS. The drawing machine is, for example, a processing apparatus that plastically processes the material M into a desired shape by drawing the material M through a die 36 while linearly moving the material M. As shown in FIGS. 8 and 9, in this embodiment, the drawing machine includes, for example, a drawing type friction test machine 30. The friction testing machine 30 reproduces a plastic processing very similar to complicated plastic deformation such as forging of automobile parts by drawing, analyzes the load acting on the material M and the die 36, and determines the contact surface between the material and the die. Friction evaluation and further evaluation of lubricant used on the surface of the material can be efficiently used for testing and evaluation.

  As shown in FIGS. 8 and 9, the friction tester 30 includes, for example, a machine frame 32, a drive unit 34 that moves the material M linearly and pulls out the die 36, and a die 36 to which the die 36 is attached. A three-dimensional load cell 10 is assembled to a die 36 of the processing unit 38. Then, the load acting on the die 36 can be measured by the three-dimensional load cell 10 during the pulling operation of the material M, and the friction coefficient of the material can be obtained from the measured value of the load using a predetermined calculation formula.

  In this embodiment, the raw material M consists of metals or alloys, such as iron and steel, for example, and the long round bar about 10-20 mm in diameter is utilized. The surface of the material M is coated with a lubricant for forging. The friction performance can be evaluated while changing the type of lubricant used for the material, and the performance of the lubricant can be evaluated. The machine frame 32 is integrally assembled with a pulling drive unit 34 and a processing unit 38. For example, a rectangular plate-like drive unit support plate 40 that supports the drive unit 34, and the drive unit support plate 40. In addition, a rectangular plate-shaped intermediate support plate 42 that is spaced apart in the horizontal direction and arranged in parallel, a plurality of support rods 44 that connect and support the two support plates 40, 42, and the support plate 42 And a U-shaped processing part support plate 46 that is fixed and supports the processing part 38. The intermediate support plate 42 and the processing portion support plate 46 are provided with through holes 48 for engaging the material M in the longitudinal direction.

  The drive unit 34 includes, for example, a drive cylinder 52 in which a chuck 50 that detachably grips and fixes one end of the material M is provided on the tip side of the cylinder rod. The drive cylinder 52 forcibly drives the material M by linearly moving the material M in the horizontal horizontal direction along the longitudinal direction with one end fixed by the chuck 50. The drive cylinder 52 is composed of, for example, a hydraulic cylinder, and a cylinder body is fixed to the drive unit support plate 40 and is connected to a hydraulic control device 53 for hydraulic control. The drive cylinder 52 is provided with a stroke measurement system 54 that measures the movement stroke amount of the material M.

  For example, the processing unit 38 is arranged in a direction orthogonal to the longitudinal direction of the material M (diameter direction of the material), and a pair of dies 36 (36a, 36b) that press the material M in a sandwiched manner, and a pair of dies 36. And a support mechanism. The support mechanism of the die 36 is a three-dimensional load cell 10 as a fixed base that fixedly supports one die 36a in a predetermined position, and the other die 36b is supported and moves in a direction close to or away from the one die 36a. A movable base 56 that is freely supported, a plurality of guide rods 58 that support the three-dimensional load cell 10 on the processing unit support plate 46 and guide and support the movable base 56, and a die that slides the movable base 56 along the guide rod 58. And a pressing cylinder 60 for applying a pressing force to the material M to 36b.

  In the present embodiment, the three-dimensional load cell 10 serves as both a load measuring unit that acts on the die and a supporting unit for the die testing machine. The three-dimensional load cell 10 is arranged on one side orthogonal to the longitudinal direction of the material M (on the lower side of the material M in the plan view of FIG. 8), and its base 12 is connected to the processing unit support plate 46 and the guide rod 58. It is fixed. As shown in FIGS. 8, 9, 10, and 11, in the three-dimensional load cell 10, the x-axis direction, that is, the passing direction of the first strain generating portion 161 is parallel to the linear movement direction L (drawing direction) of the material M. It is installed to become. The second strain generating portion 162 is provided along the horizontal direction W, that is, the pressing direction of the die in a direction orthogonal to the drawing direction L. The third strain generating portion 163 is provided along the height direction H. A die holder 64 is disposed in a fitting shape and attached via a bolt or the like to the receiving recess 22 of the load receiving portion 14 of the three-dimensional load cell 10, and the die 36 a is fixed to the die holder 64 so as to be attachable and detachable. The strain gauge 18 of the three-dimensional load cell 10 includes, for example, a bridge circuit 24 inside, and calculates the load P, component forces Px, Py, Pz, angles θx, θy, θz, friction coefficients, and the like, and outputs measurement results. , Connected to a load measurement system 66 for performing monitor display and recording.

  The movable table 56 is, for example, a rectangular plate-shaped movable support plate 56a formed to be slidable in the horizontal direction W along the longitudinal direction of the guide rod 58, and fixed to a part of one surface of the movable support plate 56a. A support base portion 56b provided with a recess for attaching a die is integrally assembled. A die holder 64 is arranged in a fitting manner in the recess of the support base portion 56b and attached via a bolt or the like, and the die 36b is fixed to the die holder 64 so as to be attachable / detachable. For example, the guide rod 58 is installed between the opposing plate portions 46 a and 46 b of the U-shaped processing portion support plate 46 in the direction W perpendicular to the drawing direction L of the material M. The pressing cylinder 60 is composed of, for example, a hydraulic cylinder, the cylinder body is fixed to the plate portion 46 a of the processing portion support plate 46, and the tip 64 a of the cylinder rod to be expanded and contracted is fixed to the movable table 56. The pressing cylinder 60 is connected to a hydraulic control device 62 for controlling hydraulic pressure.

  The dies 36a and 36b are formed of, for example, a flat die in which two flat surfaces form a chisel blade-shaped die tip with a predetermined cutting edge angle. The dies 36 a and 36 b have a linear cutting edge applied in a direction orthogonal to the longitudinal direction of the material M. The die may be, for example, a hemispherical protrusion provided at the tip of the die, or may be formed in a wave shape in which unevenness is repeatedly formed, or any other according to various forging conditions. A pattern having a die shape may be appropriately selected.

  Although not shown, the friction tester 30 cools a heating system that heats the die 36 and the material M by electromagnetic induction, a temperature control system for the heating system, a temperature measurement system that measures the temperature of the die, the load cell 10, and the like. A cooling system or the like is provided.

  When the friction test is performed, the pressing cylinder 60 is driven to move the movable table 56 along the horizontal direction W, and pressurization is performed while sandwiching the material M from both sides with the dies 36a and 36b. In a state where the material is pressurized at a constant pressure by the dies 36a and 36b, the drive cylinder 52 is driven to linearly move the material M along the drawing direction (L) to drive the material. It is plastically deformed (Ma) in a flattened shape over a direction. At this time, the load cell 10 measures the load P acting on the die 36a and the component forces Px, Py, and Pz in the x-axis, y-axis, and z-axis directions. Then, using the measurement results of the load and the component force, the direction (θx, θy, θz) in which the load is applied, and the friction coefficient of the material surface can be obtained using a predetermined calculation formula. As described above, the three-dimensional load cell is provided with the first, second, and third strain generating portions in three different directions. As a result, the load can be accurately measured with high accuracy. Measurement (calculation) can also be performed accurately with high accuracy. In the present embodiment, the friction tester 30 has been described using an example in which the three-dimensional load cell 10 of FIG. 1 is used. For example, when a load of several tf or more is applied, the three-dimensional load cell 10a of FIG. May be used. At this time, it is preferable that one first strain generating portion 161 provided in the x-axis direction is set in parallel in the drawing direction of the material M. The load cell 10 is not limited to the friction test machine 30 as described above, and may be applied to a drawing machine that actually manufactures a product by plastically deforming a material into a predetermined target shape. Further, the three-dimensional load cell 10 is not limited to a drawing machine, and can be applied to various load measurements such as a pressurizing machine, a die press machine, a production line such as forging and casting, a testing machine for materials and products, and the like. it can.

  As described above, in the three-dimensional load cell according to the present embodiment, the base 12 and the load receiving portion 14 supported with a gap G between the base 12 and one end fixed to the base 12 and the other end receiving the load. A plurality of strain generating portions that are fixed to the portion 14 and support the load receiving portion on the base, and generate strain when the load receiving portion 14 receives a load, and intersect the arbitrary first direction and the first direction. The first and second bridges are provided between the base portion and the load receiving portion in the three directions of the second direction and the third direction intersecting the plane including the first direction and the second direction. 2 and 3rd strain generating part 161,162,163, and the load of one direction like the conventional load cell by including the strain gauge 18 attached to each of the 1st, 2nd, 3rd strain generating part Those that can only be measured, and those that can be attached with a strain gauge, such as the load cell of Patent Document 1. Compared with a two-dimensional configuration in which the system is arranged in a cross shape only in the two directions of the x-axis and y-axis, the component force in the three-dimensional component direction of the load can be measured more accurately, and the measurement accuracy A high load cell can be provided. Therefore, for example, it can be used in a friction tester or the like to enable accurate measurement of the friction coefficient, thereby realizing a highly reliable friction test and performance evaluation of the material lubricant. Furthermore, a high-value load cell can be provided with a simple structure, and can be used in a wide range of fields in load measurement.

  The three-dimensional load cell of the present invention described above is not limited to the configuration of only the above-described embodiment, and may be modified arbitrarily without departing from the essence of the present invention described in the claims. Good.

  The three-dimensional load cell of the present invention is applied to, for example, any other load measurement such as a measuring instrument, a testing machine such as a friction testing machine or a material testing machine, a processing machine such as press working, casting or forging.

DESCRIPTION OF SYMBOLS 10 3D load cell 12 Base 14 Load receiving part 161-163 1st-3rd strain generation part 18 Strain gauge 30 Friction tester G Gap

Claims (5)

The base,
A load receiver supported with a gap between the base and
One end is fixed to the base portion, the other end is fixed to the load receiving portion, the load receiving portion is supported by the base portion, and a plurality of strain generating portions that generate distortion when the load receiving portion receives a load. Crossing between the base portion and the load receiving portion in three directions: a direction, a second direction intersecting the first direction, and a third direction intersecting a plane including the first direction and the second direction First, second, and third strain generating portions provided in a shape;
And a strain gauge attached to each of the first, second, and third strain generating portions.   The first, second, and third strain generating portions are provided in a spanning manner between the load receiving portion and the base portion along three axial directions orthogonal to each other. Dimensional load cell. The three-dimensional load cell is a load cell that measures a load acting on a die in a drawing process in which the material is drawn and passed through a die while being linearly moved to plastically process the material into a desired shape.
The load receiving part has a die attaching part for attaching a die,
The first strain portion is provided along a first axis direction parallel to the linear movement direction of the material,
The second strain generating portion is provided along the second axis direction orthogonal to the first axis direction,
3. The three-dimensional load cell according to claim 1, wherein the third strain generating portion is provided along a third axial direction that is orthogonal to both the first axial direction and the second axial direction. The base is provided in a partially cut-out box shape with one corner cut out and recessed,
The three-dimensional load cell according to any one of claims 1 to 3, wherein the load receiving portion is installed at a notch recessed position of the base portion. The three-dimensional load cell according to any one of claims 1 to 4, wherein the base portion, the load receiving portion, and the first, second, and third strain generating portions are integrally formed.

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