An apparatus and method for on-line measurement of the shape of a curved part

Abstract

The present application relates to the technical field of online measurement, in particular to a kind of bending part shape online measurement device and method, online measurement device includes sensor fixing seat, displacement sensor and control system, a plurality of the displacement sensor is arranged at the outlet of bending die by the sensor fixing seat annular array, and the detection end of the displacement sensor is towards the center of sensor fixing seat, the signal end of the displacement sensor is connected with the control system, the displacement sensor is used to collect the displacement signal of the bending part from the bending die, and the control system is used to analyze the displacement signal collected by the displacement sensor.The present application detects the change of the outer diameter displacement of bending part at section by setting displacement sensor at the outlet of bending die, obtains the offset of the axis at section of part in forming process, calculates the curvature and flexure of bending part by offset, realizes online measurement part shape.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of online measurement technology, in particular to a kind of bending part shape online measurement device and method. BACKGROUND

[0002] At present, the bending deformation mode of metal pipe and profile is generally plane bending, mainly including bending, stretch bending, press bending, push bending, roll bending and other processes. These methods can only be used for the bending parts with single axis form and constant bending radius. However, in recent years, the spatial configuration of metal bending parts is gradually complex, and the axis form of the bending part gradually evolves from plane form to space form. For the complex bending components with spatial complex shape or continuously changing bending radius, the traditional bending process has great application limitations. Therefore, free bending forming gradually becomes the technical innovation hotspot in the field of plastic forming at home and abroad. This technology not only can realize accurate dieless bending, effectively save the mold design and production link, shorten the mold preparation period and reduce the production cost. However, due to material springback, complex boundary conditions and other reasons, the precision of the formed parts is poor, and the process parameter adjustment period is long, which affects the application of free bending process in military, automobile and other fields.

[0003] The existing free bending parts have no precision feedback in the forming process, and can only be measured offline after processing. According to the deviation between the actual part and the theoretical part, correction is carried out, which leads to the inability to accurately control the forming precision of the parts, the inability to quickly obtain the target part shape, and the long debugging period. SUMMARY

[0004] (I) Technical problem to be solved

[0005] The present application provides a kind of bending part shape online measurement device and method, solve the technical problem that the existing free bending part in the forming process has no precision feedback, can only be measured offline after processing.

[0006] (II) Technical scheme

[0007] In the first aspect, the present application provides a kind of bending part shape online measurement device, including sensor fixing seat, displacement sensor and control system, a plurality of displacement sensors are arranged in the form of ring array at the outlet of bending die through the sensor fixing seat, and the detection end of the displacement sensor is towards the center of the sensor fixing seat, the signal end of the displacement sensor is connected with the control system, the displacement sensor is used to collect the displacement signal of the bending part from the bending die, and the control system is used to analyze the displacement signal collected by the displacement sensor.

[0008] Further, the sensor fixing seat is connected with the bending mold fixing seat of the bending mold through bolts, so that the bending part is in contact with the displacement sensor at the starting position; the displacement sensor is connected through screws or grooves arranged on the sensor fixing seat; the horizontal distance between the displacement sensor and the outlet of the bending mold is 5mm-100mm.

[0009] Further, the displacement sensor is one or more of a laser displacement sensor, a resistance displacement sensor and an inductance displacement sensor.

[0010] Further, the displacement sensor is a resistance displacement sensor or an inductance displacement sensor, the contact part of the displacement sensor with the bending part is made of wear-resistant alloy material and coated with a dry film lubricating coating; the contact part is provided with a roller, and the runout accuracy of the roller is 1 / 4 of the detection accuracy of the displacement sensor.

[0011] In the second aspect, a method for on-line measurement of the shape of a bending part is provided, and the method comprises:

[0012] determining the parametric equation H of the bending part;

[0013] rotating the bending part by an angle α around the X axis, making the tangent line at the point A0 of the bending part axis parallel to the X axis, and the transformation matrix is R x (α);

[0014] wherein R is the radius of the bending part axis, and b is the parameter of the pitch h, b=h / 2π;

[0015] moving the bending part along the negative direction of the X axis by a distance t, t=-R, so that the starting point A of the bending part axis becomes the origin in the new coordinate system;

[0016] rotating the bending part by an angle β along the Y axis, and obtaining β from the X axis translation displacement x m and the Z axis translation displacement z m of the bending mold in the machine tool control system, the transformation matrix is R y (β), and the equation of the bending part is obtained after transformation;

[0017] analyzing the equation of the bending part through the displacement of the displacement sensor, and detecting the shape of the bending part in real time; comparing the detected shape with the target value of the numerical model, and correcting through the numerical control system, so that the shape of the bending part meets the requirements of the numerical model.

[0018] Further, the parametric equation H of the bending part is:

[0019]

[0020] Wherein, r is the radius of the curved part, u, v are parameters;

[0021] The general equation of the curved part is:

[0022]

[0023] Briefly:

[0024] F(x, y, z, R, b, r) = 0;

[0025] The above parameter equation is written in the form of a matrix

[0026] According to the parameter equation, the curved part is obtained with the Z axis as the axis, and the intersection A0 of the axis and the X axis is (R, 0, 0).

[0027] Further, the transformation matrix is R x (α):

[0028]

[0029] The above parameter equation is written in the form of a matrix

[0030]

[0031] The above matrix is briefly written as A1, A1 = R x (α)A.

[0032] Further, the curved part is moved along the X axis in the negative direction by a distance t, t = -R, so that the starting point A of the curved part axis becomes the origin in the new coordinate system, and is written in the form of a matrix

[0033]

[0034] The above matrix is briefly written as A2, A2 = A1 + t(-R).

[0035] Further, the transformation matrix is R y (β):

[0036]

[0037] The above matrix is briefly written as A3, A3 = R y (β)A2;

[0038] Then

[0039] The transformed equation is briefly written as the equation of the curved part F(u, v, R, b, r, α, β) = 0.

[0040] Further, the equation for analyzing the bending part through the offset of the displacement sensor is specifically: let y=S, the curve obtained by the intersection of the bending part and the plane y=S, S is the horizontal distance between the displacement sensor and the outlet of the bending die, and the cross section is the cross section where the displacement sensor is located;

[0041] The offset L of the sensor is obtained as follows:

[0042]

[0043] For the displacement of the displacement sensor with the number of N, the displacement sensor with a larger number is selected, and the displacement sensor is calculated according to the angle between the Z-axis, wherein the first displacement sensor has an angle θ of 0 with the Z-axis, and the number is L1, the second displacement sensor has an angle θ of 0 with the Z-axis, and the number is L2, and the Nth displacement sensor has an angle θ of 0 with the Z-axis, and the number is LN. The number is L2, and the Nth displacement sensor has an angle θ of 0 with the Z-axis, and the number is LN. The number is L2, and the Nth displacement sensor has an angle θ of 0 with the Z-axis, and the number is LN.

[0044]

[0045]

[0046] The equation for analyzing the bending part is F(u,v,R,b,r,α,β)=0, and the unknown quantities in the equation are u, v, R, b, at least two displacement sensor numbers Lm and Ln (m,n∈[1,N]), and the equations are solved simultaneously:

[0047]

[0048] R and b are solved.

[0049]

[0050]

[0051] The curvature κ and the torsion τ are solved by the above formula.

[0052] (Three) beneficial effects

[0053] In summary, the displacement sensor is arranged at the outlet of the bending die, the change of the displacement of the outer diameter of the bending part at the cross section is detected in real time, the offset of the axis at the cross section of the part in the forming process is obtained, the curvature and the torsion of the bending part are calculated from the offset, and the shape of the part is measured on line.

[0054] (1) By comparing with the corresponding curvature and torsion of the numerical model, the forming parameters are corrected in real time, the part forming precision is improved, and the process iteration efficiency is improved;

[0055] (2) Real-time record the corresponding relationship between the part shape and the process parameters, improve the accumulation speed of the process knowledge base;

[0056] (3) Adopt the non-contact measurement sensor or the dry film lubrication for the sensor contact head, so as to avoid scratching the surface of the curved part. BRIEF DESCRIPTION OF DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and any other drawings can be obtained by those skilled in the art without creative labor on the premise of not departing from the spirit of the present application.

[0058] Figure 1 is a structural schematic diagram of a curved part shape on-line measurement device according to some embodiments of the present application;

[0059] Figure 2 is a front view schematic diagram of Figure 1 ;

[0060] Figure 3 is a partial schematic diagram of a curved part shape on-line measurement device according to some embodiments of the present application;

[0061] Figure 4 is a displacement sensor measurement schematic diagram according to some embodiments of the present application;

[0062] Figure 5 is a structural schematic diagram of a curved part shape on-line measurement device according to some other embodiments of the present application;

[0063] Figure 6 is a displacement sensor schematic diagram of Figure 5 ;

[0064] Figure 7 is a displacement sensor measurement schematic diagram according to some other embodiments of the present application;

[0065] In the drawings: 1, curved die fixing seat; 2, sensor fixing seat; 3, inductive displacement sensor; 4, curved die; 5, curved part; 31, laser displacement sensor. DETAILED DESCRIPTION

[0066] The embodiments of the present application will be further described in detail below in combination with the drawings and the embodiments. The detailed description of the following embodiments and the drawings are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, i.e. the present application is not limited to the described embodiments, and covers any modification, replacement and improvement of the parts, components and connection modes without departing from the spirit of the present application.

[0067] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0068] Please refer to Figures 1-7 The embodiment of the present application provides a kind of bending part shape online measuring device, including sensor fixed seat 2, displacement sensor and control system, multiple displacement sensors are arranged in the outlet of bending die 4 by the annular array of sensor fixed seat 2, and the detection end of displacement sensor is towards the center of sensor fixed seat 2, the signal end of displacement sensor is connected with the control system, and displacement sensor is used to collect the displacement signal of bending part 5 from bending die 4, and the control system is used to analyze the displacement signal collected by displacement sensor.Bending die 4 is the key of free bending forming, it is in the space translation and rotation, so that bending part 5 is bent and formed, by setting displacement sensor at the outlet of bending die 4, the change of outer diameter displacement of bending part 5 at section is detected in real time, the offset of part section axis in forming process is obtained, the curvature and flex rate of bending part 5 are calculated by algorithm from offset, and the shape of part is measured on line.

[0069] Free bending processing principle: push pipe or profile through guide mechanism and bending die by feeding mechanism (feeding device plus clamping device), bending die changes motion trajectory and posture according to the requirements of digital model along the translation of XZ axis and the rotation around XYZ axis, so that pipe or profile produces bending and torsion, and realizes continuous bending forming of pipe or profile in multiple sections and multiple directions.

[0070] In some embodiments, the sensor fixed seat 2 is connected with the bending die fixed seat 1 of bending die 4 by bolt, so that bending part 5 is in contact with the displacement sensor in starting position, and it can also be made into an integrated fixed seat, i.e. fixed bending die 4 and fixed displacement sensor; The displacement sensor is connected by screw or slot provided on the sensor fixed seat 2; According to the size of part and the size of sensor probe, 2 to 20 displacement sensors are arranged around sensor fixed seat 2, the sensor is away from the contact position of bending die 4 and bending part 5, according to the size of diameter of bending part 5 and sensor entity size, the horizontal distance between displacement sensor and the outlet of bending die 4 is 5mm-100mm.

[0071] In some embodiments, the displacement sensor employs one or more of a laser displacement sensor 31, a resistive displacement sensor, and an inductive displacement sensor 3, with a detection accuracy of μm or higher. The resistive displacement sensor and the inductive displacement sensor 3 have a self-resetting design. When a laser displacement sensor 31 is selected, its measurement position is slightly smaller than the diameter of the bent part 5 by 1mm to 5mm. When a resistive displacement sensor or an inductive displacement sensor 3 is selected, its initial detection position is slightly smaller than the diameter of the bent part 5 by 1mm to 5mm to ensure close contact between the sensor and the bent part 5.

[0072] In some embodiments, the displacement sensor is a resistive displacement sensor or an inductive displacement sensor 3. The contact part between the displacement sensor and the bent part 5 is made of a wear-resistant alloy material and coated with a dry film lubricating coating to reduce the friction between the contact part and the bent part 5 and reduce the risk of the sensor scratching the bent part 5. The contact part is provided with a roller to further reduce the friction, and the runout accuracy of the roller is 1 / 4 of the detection accuracy of the displacement sensor.

[0073] Secondly, a method for online measurement of the shape of a bent part is provided, the method comprising:

[0074] The parametric equation H of the bent part 5 is determined as follows:

[0075]

[0076] In the formula, R is the radius of the axis of the bent part 5, r is the radius of the bent part 5, b is the parameter of the pitch h, b=h / 2π, u, v are parameters;

[0077] The general equation for the bent part 5 is:

[0078]

[0079] In short:

[0080] F(x,y,z,R,b,r)=0;

[0081] Rewrite the above parametric equations in matrix form

[0082] According to the parametric equation, the bending part 5 has the Z-axis as its axis, and the intersection point A0 of the axis and the X-axis is (R,0,0).

[0083] The bent part 5 rotates by an angle α around the X-axis. Make the tangent at point A0 on the axis of the bent part 5 parallel to the X-axis, with the transformation matrix R. x (α):

[0084]

[0085] Right now

[0086]

[0087]

[0088] Abbreviated as A1 = R x (α)A.

[0089] The bent part 5 moves a distance t along the negative X-axis, where t = -R, so that the starting point A of the axis of the bent part 5 becomes the origin in the new coordinate system, specifically:

[0090]

[0091] It can be abbreviated as A2 = A1 + t(-R).

[0092] The bending part 5 rotates by an angle β along the Y-axis, and the X-axis translational displacement x of the bending die 4 is obtained from the machine tool control system. m and Z-axis translational displacement z m According to the formula The transformation matrix is ​​calculated to be R. y (β):

[0093]

[0094] Abbreviated as A3 = R y (β)A2;

[0095] but

[0096] The transformed equation can be simplified to the equation for the bent part as F(u,v,R,b,r,α,β)=0.

[0097] Please refer to Figure 3 Furthermore, the equation for the bending part 5 is specifically derived by analyzing the offset of the displacement sensor: Let y = S, and obtain the curve obtained by the intersection of the bending part 5 and the plane y = S, where S is the horizontal distance between the displacement sensor and the exit of the bending mold 4, and the cross section is the cross section where the displacement sensor is located.

[0098] Obtained from the sensor offset L:

[0099]

[0100] Please refer to Figure 451 represents the initial cross-section of the part; 52 represents the external cross-section of the part at the plane where the sensor is located after forming; S1~S8: sensor serial number; L1~L8: sensor reading; For the displacement of N displacement sensors, the displacement sensor with the larger reading is selected, and the calculation is performed based on the angle between the displacement sensor and the Z-axis. The first displacement sensor has an angle θ of 0 with the Z-axis, and its reading is recorded as L1. The second displacement sensor has an angle θ of 0 with the Z-axis... Its reading is denoted as L2, and so on. The angle θ between the Nth displacement sensor and the Z-axis is... Its reading is denoted as LN, and we obtain:

[0101]

[0102]

[0103] The equation for the bent part 5 is F(u,v,R,b,r,α,β)=0, where the unknowns are u,v,R,b, and at least two displacement sensor readings Lm,Ln (m,n∈[1,N]). Solving the system of equations:

[0104]

[0105] We can solve for R and b;

[0106]

[0107]

[0108] The curvature κ and torsion τ can be obtained by solving the above formula.

[0109] The equation of the bent part 5 is analyzed by displacement sensor offset analysis, the shape of the bent part 5 is detected in real time, compared with the target value of the digital model, and corrected by CNC system so that the shape of the bent part 5 meets the requirements of the digital model.

[0110] Example 1:

[0111] The free bending equipment controls the translation and rotation of the bending die 4 in space to bend the part 5 into shape. An online shape measurement device for the bent part 5 is also included. Figures 1-4 As shown, the system includes a sensor mounting base 2, displacement sensors, and a control system. The displacement sensors are evenly distributed circumferentially at the exit of the bending die 4.

[0112] The sensor mounting base 2 and the bending die mounting base 1 are fastened together with bolts, ensuring that each displacement sensor can contact the bending part 5 when the bending die 4 is in the initial position. The displacement sensors are fastened with screws, see... Figure 1Based on the size of the parts and the size of the displacement sensor probes, eight displacement sensors are installed around the circumference of the fixing seat of bending mold 4. See Figure 2 The distance between the displacement sensor and the contact point between the bending mold 4 and the bending part 5 is set to 20mm, based on the diameter of the bending part 5 and the size of the sensor.

[0113] An inductive displacement sensor 3 can be selected as the displacement sensor, and the detection accuracy of the inductive displacement sensor 3 needs to reach the 2μm level or above. The inductive displacement sensor 3 has a spring self-resetting design.

[0114] The initial detection position of the inductive displacement sensor 3 is slightly smaller than the diameter of the bent part 5 by 1mm to 5mm to ensure that the inductive displacement sensor 3 is in close contact with the bent part 5.

[0115] The part of the inductive displacement sensor 3 that contacts the bent part 5 is a high-precision cemented carbide Cr12MoV roller coated with a molybdenum disulfide dry film lubricating coating, which reduces the friction between the bent part 5 and the probe and reduces the risk of the inductive displacement sensor 3 scratching the bent part 5.

[0116] The inductive displacement sensor 3 is electrically connected to the control system, transmitting the displacement signal acquired by the inductive displacement sensor 3. The control system is used to analyze the signal acquired by the inductive displacement sensor 3.

[0117] The measurement principle of its bent part 5 is as follows.

[0118] The underlying assumptions of the measurement principle are as follows: Considering that the measurement point is relatively close to the bending part, it is assumed that the axis of the bending part 5 between the contact point of the inductive displacement sensor 3 and the bending mold 4 and the bending part 5 and the measurement point is a general spiral, and the bending part 5 at this point is a helical tube.

[0119] The parametric equation H of the spiral tube is as follows. Typically, a bent part 5 with a diameter of 20 is selected for the corresponding calculation.

[0120]

[0121] In the formula, R is the radius of the spiral tube axis, r is the radius of the bent part 5, b is the parameter of the pitch h, b=h / 2π, and u and v are parameters.

[0122] Write the parametric equation in matrix form

[0123] As can be seen from the parametric equations, the above-mentioned spiral tube has the Z-axis as its axis, and the intersection point A0 of the axis and the X-axis is (R,0,0).

[0124] To align with the Frenet frame of the free-bending part 5, the following transformations are made.

[0125] (1) The spiral tube rotates around the X-axis by an angle α. Make the tangent at point A0 on the axis of the solenoid parallel to the X-axis, with the transformation matrix R. x (α).

[0126]

[0127] Right now

[0128]

[0129] Abbreviated as A1 = R x (α)A.

[0130] (2) The solenoid moves a distance t along the negative X-axis. t = -R, making the starting point A of the solenoid's axis the origin in the new coordinate system. That is...

[0131]

[0132] It can be abbreviated as A2 = A1 + t(-R).

[0133] 3) The spiral tube rotates around the Y-axis. Due to the requirements of part forming, the transformed spiral tube also needs to rotate around the Y-axis, β being the translational displacement x of the bending die 4 along the X-axis. m and Z-axis translational displacement z m The decision can be obtained from the machine tool control system. The transformation matrix is ​​R y (β).

[0134]

[0135] Abbreviated as A3 = R y (β)A2;

[0136] The equation for the spiral tube is F(u,v,R,b,r,α,β)=0;

[0137] See Figure 3 Let y = S, we can obtain the curve obtained by the intersection of the spiral tube and the plane y = S. This cross section is also the cross section where the inductive displacement sensor 3 is located.

[0138] From the offset L of the inductive displacement sensor 3, we can know that:

[0139]

[0140] This embodiment uses eight inductive displacement sensors 3, see Figure 4An inductive displacement sensor 3 with a larger reading is selected. Based on the angle between the inductive displacement sensor 3 and the Z-axis, corresponding calculations are performed. The first inductive displacement sensor 3 has an angle θ of 0 with the Z-axis, and its reading is denoted as L1. The second inductive displacement sensor 3 has an angle θ of [missing value]. Its reading is denoted as L2, and so on. The angle θ between the 8th inductive displacement sensor 3 and the Z-axis is... Its reading is denoted as L8.

[0141] It can be known

[0142]

[0143]

[0144] The equation for the spiral tube is F(u,v,R,b,r,α,β)=0. It can be seen that the unknowns in this equation are u, v, R, and b. Then, by reading the larger readings of the inductive displacement sensor 3, Lm and Ln (m,n∈[1,8]), the following equation can be obtained by combining the equations and solving for R and b.

[0145]

[0146] For a typical spiral:

[0147]

[0148]

[0149] This allows for real-time detection of the shape of the bent part 5, comparison with the target value of the digital model, and subsequent corrections via the CNC system to ensure the shape of the bent part 5 meets the requirements of the digital model. According to the free bending forming law, κ is directly proportional to the translation distance of the bending die 4 and the deflection angle perpendicular to the translation direction; τ is directly proportional to the deflection angle of the bending die 4 (excluding the translation-related deflection component). If the curvature is too small, the translation distance of the bending die 4 is increased to increase the subsequent curvature and compensate for the initial small curvature; if the curvature is too large, the opposite is true. If the deflection is too small, the deflection angle of the bending die 4 is increased to increase the subsequent deflection and compensate for the initial small deflection; if the deflection is too large, the opposite is true.

[0150] Example 2:

[0151] The free bending equipment controls the translation and rotation of the bending die 4 in space to bend the part 5 into shape. An online shape measurement device for the bent part 5 is also included. Figures 5-7 As shown, the system includes a sensor mounting base 2, displacement sensors, and a control system (not shown). Two displacement sensors with overlapping measuring surfaces and perpendicular to each other are arranged at the exit of the bending die 4. Figure 5 .

[0152] The sensor mounting base 2 and the bending die mounting base 1 are fastened together with bolts to ensure that when the bending die 4 is in the initial position, the center of the bending part 5 is at the center of the measurement position. The displacement sensor is fastened with screws.

[0153] Based on the size of the part and the size of the displacement sensor probe, two displacement sensors are installed around the base of the bending mold 4. The distance between the displacement sensors and the contact point between the bending mold 4 and the bending part 5 is set to 20mm, based on the diameter of the bending part 5 and the size of the displacement sensor.

[0154] A laser displacement sensor 31 can be selected as the displacement sensor, see [link / reference]. Figure 6 The laser displacement sensor 31 needs to achieve a detection accuracy of 2μm or higher. The measurement center of the laser displacement sensor 31 coincides with the center of the bending mold 4.

[0155] The laser displacement sensor 31 consists of a laser emitter 311, a laser receiver 312, and a laser displacement sensor control system (not shown). The sensor measurement area 315 is located between the first measurement boundary line 313 and the second measurement boundary line 314.

[0156] The laser displacement sensor 31 is electrically connected to the control system, transmitting the displacement signal acquired by the laser displacement sensor 31. The control system is used to analyze the signal acquired by the laser displacement sensor 31.

[0157] The measurement principle of its bent part 5 is as follows.

[0158] The underlying assumptions of the measurement principle are as follows: Considering that the measurement point is relatively close to the bending part, it is assumed that the axis of the bending part 5 between the contact point between the laser displacement sensor 31 and the bending mold 4 and the bending part 5 and the measurement point is a general spiral, and the bending part 5 at this point is a helical tube.

[0159] The parametric equation H of the spiral tube is as follows. Typically, a bent part 5 with a diameter of 20 is selected for the corresponding calculation.

[0160]

[0161] In the formula, R is the radius of the spiral tube axis, r is the radius of the bent part 5, b is the parameter of the pitch h, b=h / 2π, and u and v are parameters.

[0162] The general equation for a spiral tube is as follows.

[0163]

[0164] This can be simplified as F(x,y,z,R,b,r)=0;

[0165] Write the parametric equation in matrix form

[0166] As can be seen from the parametric equations, the above-mentioned spiral tube has the Z-axis as its axis, and the intersection point A0 of the axis and the X-axis is (R,0,0).

[0167] To align with the Frenet frame of the free-bending part 5, the following transformations are made.

[0168] (1) The spiral tube rotates around the X-axis by an angle α. Make the tangent at point A0 on the axis of the solenoid parallel to the X-axis, with the transformation matrix R. x (α).

[0169]

[0170] Right now

[0171]

[0172] Abbreviated as A1 = R x (α)A.

[0173] (2) The solenoid moves a distance t along the negative X-axis. t = -R, making the starting point A of the solenoid's axis the origin in the new coordinate system. That is...

[0174]

[0175] It can be abbreviated as A2 = A1 + t(-R).

[0176] (3) The spiral tube rotates around the Y-axis. Due to the requirements of part forming, the transformed spiral tube also needs to rotate around the Y-axis, β being the translational displacement x of the bending die 4 along the X-axis. m and Z-axis translational displacement z m The decision can be obtained from the machine tool control system. The transformation matrix is ​​R y (β).

[0177]

[0178] Abbreviated as A3 = R y (β)A2;

[0179] The equation for the spiral tube is F(u,v,R,b,r,α,β)=0;

[0180] Let y = S, we can obtain the curve obtained by the intersection of the helical tube and the plane y = S. This cross section is also the cross section where the laser displacement sensor 31 is located.

[0181] See Figure 7H1 to H4 are the sensor readings, and L11, L21, L31, and L41 are the offsets calculated from the sensor readings. Based on the part of the bent part 5 that is blocked, H1, H2, H3, and H4 can be read from the laser displacement sensor 31. Then, based on the relative positional relationship between the laser displacement sensor 31 and the bending mold 4, the outer diameter positions L11, L21, L31, and L41 of the bent part 5 at the extreme point of the bent part 5 can be calculated.

[0182] The general equation for analyzing a spiral tube is F(x,y,z,R,b,r,α,β)=0, where y=20. This gives us the equations z=P(x,20,R,b,10,α,β) and x=Q(z,20,R,b,10,α,β).

[0183] Using the extreme value formula Solving for x11 and x12, we get |x11|≥|x12|; the extremum formula. Solving for z21 and z22, we get |z21|≥|z22|. Using the angle β, we determine the extreme values ​​corresponding to x11, x12, z21, and z22. Taking β as an angle of 135 degrees as an example, we can then solve the following equations to obtain R and b.

[0184] L11=z12=P(x12,20,R,b,10,α,β);

[0185] L21=z11=P(x11,20,R,b,10,α,β);

[0186] L31=x21=Q(z21,20,R,b,10,α,β);

[0187] L41=x22=Q(z22,20,R,b,10,α,β);

[0188] For a typical spiral

[0189]

[0190]

[0191] This allows for real-time detection of the shape of the bent part 5, comparison with the target value of the digital model, and subsequent corrections by the CNC system to ensure the shape of the bent part 5 meets the requirements of the digital model. If the curvature is too small, the translation distance and corresponding deflection angle of the bending die 4 are increased to increase the subsequent curvature and compensate for the initial small curvature; if the curvature is too large, the opposite process is performed. Similarly, if the deflection is too small, the deflection angle of the bending die 4 is increased to increase the subsequent deflection and compensate for the initial small deflection; if the deflection is too large, the opposite process is performed.

[0192] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For the embodiments of the method, relevant parts can be referred to the description of the device embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0193] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for online measurement of the shape of a bent part, characterized in that, A bending part shape online measurement device is used for measurement. The online measurement device for bending part shape includes a sensor mounting base, a displacement sensor, and a control system. Multiple displacement sensors are arranged in a ring array at the exit of the bending die through the sensor mounting base, and the detection end of the displacement sensor faces the center of the sensor mounting base. The signal end of the displacement sensor is connected to the control system. The displacement sensor is used to collect the displacement signal of the bending part entering and exiting the bending die. The control system is used to analyze the displacement signal collected by the displacement sensor. The displacement sensor is a resistive displacement sensor or an inductive displacement sensor. The contact part between the displacement sensor and the bending part is made of wear-resistant alloy material and coated with a dry film lubricating coating. The contact portion is equipped with a roller, and the runout accuracy of the roller is 1 / 4 of the detection accuracy of the displacement sensor; the method includes the following steps: Determine the parametric equation H of the bent part; The bent part rotates by an angle α around the X-axis. Make the tangent at point A0 on the axis of the bent part parallel to the X-axis, with the transformation matrix R. x (α); The bent part moves a distance t along the negative X-axis, where t = -R, so that the starting point A of the bent part's axis becomes the origin in the new coordinate system; The bent part rotates by an angle β along the Y-axis. β is obtained from the X-axis translational displacement x of the bending die, which is determined by the machine tool control system. m and Z-axis translational displacement z m , The transformation matrix is ​​R y (β), after transformation, the equation of the bent part is obtained; The equation of the bent part is analyzed by displacement sensor offset analysis, the shape of the bent part is detected in real time, compared with the target value of the digital model, and corrected by CNC system so that the shape of the bent part meets the requirements of the digital model.

2. The method for online measurement of the shape of a bent part according to claim 1, characterized in that: The sensor mounting base is bolted to the bending die mounting base of the bending die, so that the bending part contacts the displacement sensor in the initial position; the displacement sensor is connected by screws or a slot provided on the sensor mounting base; the horizontal distance between the displacement sensor and the outlet of the bending die is 5mm to 100mm.

3. The method for online measurement of the shape of a bent part according to claim 1, characterized in that: The parametric equation H for the bent part is: In the formula, R is the radius of the axis of the bent part, r is the radius of the bent part, b is the parameter of the pitch h, b=h / 2π, u, v are parameters; The general equation for a bent part is: In short: F(x,y,z,R,b,r)=0; Rewrite the above parametric equations in matrix form According to the parametric equation, the bending part has the Z-axis as its axis, and the intersection point A0 of the axis and the X-axis is (R,0,0).

4. The method for online measurement of the shape of a bent part according to claim 3, characterized in that: The transformation matrix is ​​R x (α): Right now Abbreviated as A1=R x (α)A.

5. The method for online measurement of the shape of a bent part according to claim 4, characterized in that: The bent part moves a distance t along the negative X-axis, where t = -R, so that the starting point A of the bent part's axis becomes the origin in the new coordinate system, specifically: It can be abbreviated as A2 = A1 + t(-R).

6. The method for online measurement of the shape of a bent part according to claim 5, characterized in that: The transformation matrix is ​​R y (β): Abbreviated as A3 = R y (β)A2; but The transformed equation can be simplified to the equation for the bent part as F(u,v,R,b,r,α,β)=0.

7. The method for online measurement of the shape of a bent part according to claim 6, characterized in that: The equation for analyzing the offset of a bent part using a displacement sensor is as follows: Let y = S, and obtain the curve obtained by the intersection of the bent part and the plane y = S, where S is the horizontal distance between the displacement sensor and the exit of the bending die, and the cross section is the cross section where the displacement sensor is located. Obtained from the sensor offset L: For N displacement sensors, the displacement sensor with the larger reading is selected. The calculation is performed based on the angle between the displacement sensor and the Z-axis. The first displacement sensor has an angle θ of 0 with the Z-axis, and its reading is recorded as L1. The second displacement sensor has an angle θ of... Its reading is denoted as L2, and so on. The angle θ between the Nth displacement sensor and the Z-axis is... Its reading is denoted as LN, and we obtain: The equation for analyzing the bent part is F(u,v,R,b,r,α,β)=0, where the unknowns are u,v,R,b, and at least two displacement sensor readings Lm,Ln (m,n∈[1,N]). Solving the system of equations: We can solve for R and b; The curvature κ and torsion τ can be obtained by solving the above formula.

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