Design and preparation method of robot tool changer

Abstract

The invention relates to the technical field of robot end tools, in particular to design and a preparation method of a robot tool changer. The known technical parameters and the known mechanical principle of the robot are utilized, the load and the torque of the bearing mechanism are accurately calculated, and tool replacers of different specifications are manufactured. The robot tool changer is designed by utilizing a lever principle and a transverse pin structure, so that the tool changer and a tail end tool are positioned on the same stress surface, and the stability of the tool changer is ensured. The tool changer adopts a split type design, and the bearing mechanism and the tool changer body are made of double-alloy materials, so that the rigidity and durability of the tool are ensured, and the characteristic of light weight of the tool is also ensured. And different surface treatment processes are adopted for two different metal materials of the tool changer, so that the wear resistance and corrosion resistance of the tool changer are ensured. According to the technical scheme, large-scale industrial production can be achieved, and the application market of continuously-developing robot tool replacers is met.

Description

Technical Field

[0001] The present invention relates to the technical field of robot end tool, and in particular to the design of a robot tool changer and a preparation method thereof. Background Art

[0002] At present, the robot tool changer adopts a circular body design and uses external compressed air as a power source. The tool changer called the main plate is installed on the flange of the sixth axis or end of the robot, and the tool changer called the sub-plate is connected to the end tool. When the main plate on the robot side is aligned with the sub-plate connected to the end tool, the robot controller guides the main plate to mechanically couple with the sub-plate and the end tool. The multiple steel balls in the robot tool changer serve as a coupling mechanism, and the piston serves as an actuator of the power source. The piston radially drives the steel ball forward and abuts against the bearing race of the tool side changer. The steel ball rolls to the bottom of the groove in the bearing seat ring or detaches from the groove, thereby achieving the coupling or separation of the robot side main plate and the tool side sub-plate. This design concept uses the bearing principle and ball lock structure. The contact point between the steel ball and the inner groove of the bearing race is used as the force point of the robot changer and the end tool, and the steel ball serves as the bearing mechanism of the changer and the end tool. This technical solution is that any three steel balls determine a force surface. In actual use, since the steel balls are at the bottom of the groove of the bearing ring seat ring, the position of each steel ball is not fixed. When the end tool is working, the steel balls will twist and move, causing the end tool to shake easily, causing the tool changer to get stuck or disengage, and the end tool torque is small. Therefore, the robot tool changer needs a mechanical principle and structural design and preparation method that meet the actual use requirements. Summary of the invention

[0003] In order to solve the technical defects of the end tool shaking of the robot changer, causing the tool changer to get stuck or out of the cavity, and the end tool torque is small, a robot tool changer is invented.

[0004] The technical solution of the present invention is that the tool changer adopts a cube structure, which is divided into a robot side main plate and a tool side sub-plate. The robot side main plate is semi-permanently fixed on the sixth axis or the flange of the end of the robot, and the tool side sub-plate is connected to the end tool. The tool changer body and the tool side body on the robot side are designed as a cavity structure. The components of the bearing mechanism are designed according to the specifications and dimensions of the cavity structure of the tool changer body, respectively installed inside the body cavity, and fixed or connected together with bolts. The body of the tool changer and the tool bearing mechanism adopt a split design, and the various components of the bearing mechanism are designed first. A geometric piston cylinder is designed inside the tool body on the robot side, so that the body is equivalent to the outer wall of the piston cylinder, and the intersection of two diagonals on a working surface of the body is used as the center of the piston cylinder. The inner diameter of the piston cylinder is the same as the inner diameter of the sixth axis or the end flange of the robot. Since the global robot flange adopts the ISO9409-1 standard, the inner diameter of the piston cylinder can be known according to the inner diameter of the sixth axis or the end flange of the robot. A piston is designed accordingly, and the outer diameter of the piston is the same as the inner diameter of the cylinder body. The piston is driven unidirectionally in the cylinder body of the robot side body geometry to form a single-acting piston cylinder. The stroke of the piston rod can be calculated based on the constraint relationship between the piston pressure and the bearing mechanism. A locking sleeve is designed, the sleeve base is designed to be circular, the locking mechanism is designed to be a regular hexagon, and the sleeve base and the locking mechanism are designed in an integrated manner. A waist hole is designed at the center of each regular hexagonal locking mechanism, and a cross pin is designed accordingly. The specifications and dimensions of the cross pins are the same and must match the specifications and dimensions of the waist hole. A gap of 0.2mm is reserved between the cross pin and the waist hole. The outer diameter of the cross pin is designed to be 3 times the thickness of the hexagonal locking mechanism. The cross pin adopts a circular structure, and an annular groove is designed in the middle. A convex point is designed at the upper center of the waist hole. The cross pin is installed in the waist hole. Due to the blocking effect of the convex point, the cross pin will be fixed in the middle of the waist hole and will not completely detach from the waist hole. The six cross pins and the six locking mechanisms of the locking sleeve together constitute the tool changer and the end tool bearing mechanism. Design a regular hexagonal lock core. In order to increase the bearing capacity of the lock core, the lock core is designed to be a double-layer structure, and the taper of the six sides of the lock core is designed to be 15°. Design a circular hole in the center of the locking sleeve. The diameter of the circular hole is consistent with the outer diameter of the piston rod. The piston rod passes through the center hole of the sleeve and is connected to the lock core with bolts. Design 6 bolt holes in the annular seat of the locking sleeve and fix it to the body on the robot side with bolts. Design a locking collar with a hollow design, a hole in the middle, and a regular hexagonal structure in the inner hole. The inner angle is 45°, and the outer diameter of the locking collar is the same as the outer diameter of the locking sleeve base. The locking collar is installed in the tool side body of the changer and fastened to the tool side body with 6 bolts.

[0005] After designing the various components of the bearing mechanism, the body of the tool changer is designed. Since the body is a split design, it does not fully bear the load and dynamic torque of the tool changer. In order to ensure the lightweight requirements of the robot tool, the tensile strength of the body material can be lower than the tensile strength of the bearing mechanism material. Design the body of the robot side tool changer, design an external flange on one of the working surfaces of the body, the flange diameter is selected according to the ISO9409-1 standard, the flange diameter is consistent with the inner diameter of the sixth axis or the end flange of the industrial robot, and the flange thickness is designed to be 5mm. Six bolt holes are reserved inside the body to facilitate the tool to be fixed with the flange of the sixth axis of the robot. A geometric piston cylinder is designed inside the cube of the robot side body. The intersection of the diagonal lines of the cube is used as the center of the piston cylinder. The inner diameter of the piston cylinder is the same as the inner diameter of the sixth axis or the end flange of the robot. The piston cylinder and the locking sleeve are concentric circles, and space for installing the locking sleeve is reserved inside the body. A sealing groove is designed on the contact surface between the piston cylinder and the locking sleeve to prevent compressed air leakage. Two positioning pins are designed at the diagonal line of the upper surface of the robot side body to facilitate the alignment of the tool changer on the robot side with the tool side changer. The tool changer body is used to install and fix the locking collar, and the size of the body cavity matches the specification size of the locking collar.

[0006] External compressed air is used as the power source of the tool changer. If an accidental air cut occurs, protective measures are required. The single-acting piston cylinder is designed inside the body of the tool changer on the robot side. It cooperates with the piston. 4-6 pressure spring inner grooves are designed at the bottom of the piston cylinder. The same size of spring inner grooves are also designed at the bottom of the piston. The piston will be restricted by the pressure spring when it moves. Even if the tool changer is in an accidental air cut, the tool changer and the end tool on the tool side will not fall off. An air intake channel is designed inside the body of the tool changer on the robot side. The air channel aperture is not greater than 1.5mm. It is directly connected to the bottom of the piston cylinder. The air channel is connected to the compression air with a quick connector, which can ensure that the external compressed gas is always in a high-pressure state. An exhaust channel is designed inside the tool changer on the robot side. The opening is designed at the top of the piston cylinder to directly drive the piston. In order to ensure good sealing between the mechanisms, a sealing ring is installed between the top of the piston cylinder and the locking sleeve.

[0007] Detection measures for coupling, loosening or separation of tool changers: Robot tool changers are all mechanical parts. Due to the manufacturing accuracy and installation deviation of the mechanical parts themselves, errors will be caused. In order to compensate for these errors, electrical control methods are used to detect the locking and loosening of tool changers or the separation of tools. Three proximity switches with LED lights are installed inside the robot side changer body. The detection distance of the proximity switch with LED lights is designed to be 1mm. Two objects to be detected are regular hexagonal lock cylinders, and one object to be detected is a locking collar. The LED lights use two colors, green and red. When the robot side changer is coupled with the tool side changer, the lock cylinder is in place and the distance is within 1mm, the LED light will display green; if the lock cylinder is not in place and the distance is greater than 1mm, the corresponding LED light will display red. The two LED light proximity switches are installed in parallel with the lock cylinder. One of the proximity switches with LED lights is installed vertically. The proximity switch is flush with the tool changer. When the tool side changer is coupled with the robot side changer, the proximity switch with LED lights displays green. When the tool side changer is separated from the robot side changer, the LED light will display red.

[0008] In actual operation, the tool changer on the robot side is fixed on the robot's sixth axis or end flange. The tool changer on the tool side is installed or fastened together with the end tool, usually placed separately. The robot controller operates the robot side changer to couple with the end tool. The tool changer is a cube structure. In order to facilitate accurate positioning of the tool changer, two locating pins are designed on the tool body on the robot side. The location of the locating pins is on the diagonal line of the cube; two pin holes are designed on the tool side body. The locating pin adopts a circular cone structure to facilitate rapid positioning of the tool changer.

[0009] The robot side changer body is designed with air intake and exhaust channels. When the piston cylinder is inhaled, the gas drives the piston, driving the lock core to move in one direction. The lock core pushes the six cross pins out of the waist hole of the locking sleeve and rests on the inner wall of the six inner sides of the tool side locking collar. The tool changer is coupled and the end tool performs work. At this time, it is equivalent to six levers jointly bearing the load and torque of the end tool. The six cross pins are in a coplanar state when the tool changer is coupled. The tool changer and the end tool are on the same force surface, which ensures the stability of the full set of tool changers and the tool changer will not get stuck or disengage from the cavity. When the single-acting piston cylinder is exhausted, the regular hexagonal lock core retracts. Due to the reverse friction, the six cross pins return to the center of the waist hole, the tool changer is separated, and the end tool stops performing work or is replaced. Compared with the ball lock tool changer of the same specification and diameter, the tool changer made by the lever principle and cross pin structure has six times the load and torque of the ball lock tool changer. In a stationary state, the load and torque of the bearing mechanism can be calculated according to the static equilibrium equation, so that tool changers with different loads and torques can be made according to the load and torque requirements.

[0010] According to the known technical parameters of the robot and the recognized mechanical principles, the mechanical equations are used to prove whether the design of the tool changer is reasonable. First, a single-acting piston cylinder is designed. The piston cylinder is designed inside the cube of the robot side body. The inner diameter of the piston cylinder is the same as the inner diameter of the flange of the sixth axis or the end of the robot. Since the inner diameter of the single-acting piston cylinder is the same as the outer diameter of the piston, the outer diameter of the piston can be determined after the inner diameter of the piston cylinder is determined. After determining the outer diameter of the piston, the diameter of the piston rod is designed. According to the design principle of the piston, the diameter ratio d / D of the piston rod and the piston is between 0.2 and 0.4. The compressed air in the factory is between 0.40 and 0.7Mpa, the actual pressure P0 is generally 0.5Mpa, and the efficiency η of gas compression is generally 0.85. According to the "Mechanical Design Manual" and the actual situation of the factory, the pressure P of the single-acting piston cylinder is calculated, and the theoretical pressure P of the single-acting piston cylinder is calculated through mathematical modeling.

[0011]

[0012]

[0013]

[0014]

[0015] The theoretical pressure P of the piston cylinder is a constant. The piston rod d∈(0.2-0.4)D. In order to facilitate the manufacture of the piston rod, d is generally a positive integer and a multiple of 5. After mathematical calculation, the theoretical pressure P of the piston cylinder is 0.334((D 2 -d 2)N. The pressure of the piston cylinder is a known quantity, and it is necessary to calculate the stroke of the piston cylinder, that is, to calculate the length of the piston rod. The piston is connected to the regular hexagonal lock core by bolts. The lock core needs to push the cross pin. The thickness of the lock core is the same as the diameter of the cross pin. In order to ensure the safety of the bearing mechanism, the thickness is 2mm larger than the cross pin diameter when the lock core is actually designed. The diameter of the lock core, the inner diameter of the piston cylinder, the diameter of the piston rod, and the pressure of the piston cylinder are all known quantities. According to the cylinder design principle, the stroke of the piston cylinder is calculated, and the length of the piston rod is calculated based on the constraint relationship between the data of these components.

[0016] The locking sleeve, piston, regular hexagonal lock core, cross pin and locking collar are combined into a load-bearing mechanism, and the cross pin is the most important component in the load-bearing mechanism. As a dynamic tool, the tool changer must be connected to the sixth axis or end flange of the industrial robot by bolts to work. In a static state, the resultant force of the cross pin in the three directions of the X-axis, Y-axis and Z-axis is zero respectively; under static conditions, the tool changer analyzes the stress state of the cross pin, the regular hexagonal lock core and the locking collar, and calculates the mechanical data of the load-bearing mechanism through mathematical modeling. The pressure of the single-acting piston cylinder is P, the diameter of the cross pin is R, and the number is 6. Ignoring the uneven force state of the cross pin, the axial balance equation of the pin core in the load-bearing mechanism is:

[0017] (1)

[0018] The cross pin is installed inside the robot tool changer. According to the principle of statics, the sum of the forces in the three directions of X-axis, Y-axis and Z-axis is 0. Figure 8 The stress analysis state of the middle cross pin, the static equilibrium equation of the cross pin is given by , , The following mathematical equation is obtained.

[0019] (2)

[0020] The combined equations (1) and (2) can be transformed by trigonometric functions to obtain:

[0021] (3)

[0022] In the mathematical equation, Ft1 is the friction force of the locking collar, Ft2 is the static friction force of the lock core on the cross pin, Fn1 is the force generated by the locking collar on the cross pin, and Fn2 is the thrust generated by the lock core on the cross pin. In the above equation, P is a constant, the value of α is 45°, and the value of β is 15°. The data of Fn, Ft2, Fn1, and Fn2 are calculated respectively. Mathematical modeling is used to perform theoretical calculations on the mechanical data of the load-bearing mechanism. When the inner angle of the locking collar is 45° and the taper value of the regular six-shaped deformation lock core is 15°, the equation takes the maximum value, indicating that the force on the cross pin is in the maximum state, the diameter of the cross pin increases, and the load-bearing capacity increases accordingly. The mechanical equation demonstrates that the design of the tool changer is reasonable.

[0023] The tool changer adopts a split design, and the bearing mechanism component and the body are made of different metal materials. First, the preparation method of the bearing mechanism component is introduced. The preparation method of the bearing mechanism component is:

[0024] 1. The bearing mechanism consists of a locking sleeve, a regular hexagonal lock core, a piston, 6 cross pins, and a locking collar. The bearing mechanism bears the load and dynamic torque of the end tool, and requires a metal material with high tensile strength. Since the tool changer is a power component installed on the sixth axis or the end flange of the industrial robot, according to the principle of mechanics, the tensile strength of the tool changer must be equal to or greater than the strength of the robot's sixth axis connection flange to be used normally. The tensile strength of the currently known sixth axis flange of industrial robots and the matching locking bolts is designed to be 1080Mpa, and the tensile strength of the tool changer can also be 1080Mpa. In view of the fact that the tool changer is a power component, the tensile strength will be attenuated, and the safety factor is designed to be 0.9, so that the tensile strength of the tool changer's load-bearing components can reach 1200Mpa. The blank is made of domestic precipitation hardened steel. Because the tensile strength of precipitation hardened steel blank cannot reach 1200Mpa before heat treatment, according to the material hardness, the material hardness and the material tensile strength are equivalent. The hardness is converted into the international general standard, that is, the hardness of the load-bearing parts after heat treatment is required to be between 340-380HBS. The bearing mechanism parts are finely processed at one time, and the dimensional tolerance is kept between ±0.025mm.

[0025] 2. Heat treatment of the bearing mechanism components, first quenching treatment, send the finished parts to the quenching furnace, heat to 850℃-900℃, then use heavy oil quenching, and then use tempering treatment, send the quenched finished parts to the tempering furnace and heat to 400℃-450℃, and finally use air cooling for 24 hours. Next, the finished parts are completely annealed, send the finished parts to the annealing furnace, heat to 650℃-700℃, keep warm for 8 hours, then slowly cool to 500℃, and then air cool; cool to room temperature. Natural aging of the finished parts, put 1 locking sleeve, 1 piston, 1 regular hexagonal lock core, 6 cross pins, and 1 locking collar in the workshop for 48 hours to release all the residual stress inside the parts naturally. After the natural aging of the finished parts is completed, clean the finished parts, use a weak alkaline solution to clean the oil and grease on the surface of the finished parts, and then wipe them clean with non-woven cloth. Professional testing instruments are used to detect the mechanical properties of the load-bearing mechanism components. The hardness of the load-bearing mechanism components is between 340-380HBS, that is, the tensile strength is between 1080-1200Mpa.

[0026] 3. The tolerance size of the load-bearing mechanism components. The components will be slightly deformed after heat treatment. In order to avoid the components from generating magnetism during the secondary processing, the deformed parts of the components are ground using a grinder to ensure that the dimensional tolerance of the load-bearing mechanism components is maintained between ±0.025mm.

[0027] 4. Surface chemical nickel plating treatment. Since industrial robots are used in aluminum electrolysis plants or aluminum foundries for new energy vehicles, under these working conditions, a hydrogen fluoride gas is precipitated from the aluminum solution during the aluminum melting process in the electrolytic cell or induction furnace. The molecular formula of hydrogen fluoride is FH, which is an acidic gas with extremely strong corrosiveness. As a supporting tool for the robot, the tool changer is easily corroded under such working conditions. Although precipitation hardened steel itself has good corrosion resistance, it is still necessary to perform chemical nickel plating on the surface of the tool changer's bearing mechanism components. Medium-phosphorus high-temperature nickel plating is used to chemically immerse all metal bearing mechanism components in the liquid tank. The solution is 4.0-5.0g / L of nickel sulfate heptahydrate, 25-30g / L of sodium acetate, and the catalyst is sodium hypophosphite with a concentration of 25-30g / L. A trace amount of fluoride salt needs to be added at a ratio of 8-12g / L. Fluoride salt is commonly known as cryolite, and its molecular formula is Na3AlF6. Practice has proved that after adding cryolite to nickel solution, the nickel coating has better wear resistance after drying. The pH value of the nickel solution is adjusted to between 4.5-5.0, the solution temperature is 85-90℃, the immersion time is 35-40min, the baking temperature is 150℃-160℃, and the baking time is 20-25 minutes. Rinse the parts with clean water for 5-6 minutes, wipe the surface of the parts clean, and after testing with professional instruments, the thickness of the nickel plating is 10±2μm.

[0028] The tool changer adopts a split design, and the tool changer body is prepared as follows:

[0029] 5. The body of the tool changer is a non-stressed component. In order to meet the technical requirements of lightweight tools, the material of the body does not need to be the same as that of the bearing mechanism, and the tensile strength can be lower than that of the bearing mechanism. According to the law of dual alloy material use, the tensile strength ratio of the two materials is ≥1 / 2. The tensile strength of the tool changer bearing mechanism material is 1080-1200Mpa. From this, it can be deduced that the tensile strength of the tool changer body can be between 540-600Mpa. The tool changer body is made of domestic low-carbon metal materials, and soft steel with a tensile strength between 540-600Mpa is selected. The structure is a cube. The body of the tool changer is divided into two parts. First, the tool changer body on the robot side is manufactured, and an external flange is designed on one working surface of the body. The flange diameter is selected according to the ISO9409-1 standard. The flange diameter is consistent with the inner diameter of the sixth axis or end flange of the industrial robot, and the flange thickness is designed to be 5mm. The robot body has a cavity inside, where a locking sleeve, a piston, a regular hexagonal lock core, and six cross pins need to be installed. The size of the cavity matches the size of these components. Three spaces and channels with LED proximity switches need to be designed inside the robot body. Next, the tool body is designed, which also has a cavity structure inside. The tool body only needs to install a locking collar, which is a bearing mechanism component. The size of the cavity matches the size of the locking collar.

[0030] 6. The two parts of the tool changer body need to be surface treated, using anodizing process to increase the hardness and corrosion resistance of the tool body surface. The coating thickness of the tool changer body is 50±5μm, and the hardness is controlled between 340-380HBS, which is consistent with the hardness of the bearing parts. The color of the tool changer body remains the natural dark brown color of anodizing.

[0031] Preferably, the two parts of the tool changer body are made of domestic low-carbon metal materials, and soft steel with a tensile strength between 540-600Mpa is selected, and the structure of the finished part is a cube.

[0032] Preferably, a robot-side tool changer body is manufactured, and an external flange is designed on a working surface of the body. The flange diameter is selected according to ISO9409-1 standard. The flange diameter is consistent with the inner diameter of the sixth axis or end flange of the industrial robot, and the flange thickness is designed to be 5 mm.

[0033] Preferably, the bearing components are 1 locking sleeve, 1 regular hexagonal lock core, 1 piston, 6 cross pins, and 1 locking collar. The blank is made of domestic precipitation hardened steel, and the bearing components are finely processed in one go, with a dimensional tolerance of ±0.025 mm.

[0034] Preferably, the locking mechanism of the locking sleeve is a regular hexagonal deformation, and a waist hole is designed at the center position of each regular hexagonal locking mechanism, and a corresponding cross pin is designed at the same time. The specifications and dimensions of the cross pins are the same, and the specifications and dimensions of the cross pins must match the waist hole. A gap of 0.2 mm is reserved between the waist hole and the cross pin, and the outer diameter of the cross pin is designed to be 3 times the thickness of the hexagonal locking mechanism.

[0035] Preferably, the lock core is designed as a regular hexagonal structure, the diameter of which is smaller than the inner diameter of the regular hexagon of the sleeve, the vertical distance between the two is 2 / 3 of the diameter of the cross pin, and the taper of the six sides of the lock core is 15°.

[0036] Preferably, the locking collar adopts a hollow design, the inner side is designed to be a regular hexagonal structure, and the inner angle is designed to be 45°.

[0037] Preferably, the load-bearing components are heat treated, first by quenching and then by tempering, followed by complete annealing of the load-bearing components, and finally natural aging of the load-bearing components for 48 hours, so that all residual stresses inside the components are naturally released, ensuring that the tensile strength of the components after heat treatment is between 1080-1200Mpa.

[0038] Preferably, the surface of the bearing component of the tool changer is treated with chemical phosphorus-nickel treatment, using medium-phosphorus high-temperature nickel plating, and a trace amount of fluoride salt is added to the nickel solution, so that the nickel coating has better wear resistance after drying, and the thickness of the nickel plating is 10μm.

[0039] Preferably, the tool changer body is treated by anodizing, the coating thickness is controlled at 50 μm, the hardness is controlled between 340-380 HBS, and the color of the tool changer body remains the natural dark brown color of anodizing.

[0040] Preferably, three proximity switches with LED lights are installed inside the robot-side changer body, and the detection distance of the LED light detection switch is set to 1 mm to detect the locking and loosening or separation of the tool changer.

[0041] The technical solution of the present invention has the following benefits: (1) By utilizing the well-known technical parameters of the robot and the well-known mechanical principles, the load and torque of the bearing mechanism can be accurately calculated, and tool changers of different specifications can be produced. (2) The robot tool changer is designed using the lever principle and the cross-pin structure, so that the tool changer and the end tool are on the same force-bearing surface, ensuring the stability of the full set of tool changers. (3) The tool changer adopts a split design, and the bearing mechanism and the tool changer body are made of dual alloy materials, which not only ensures the rigidity and durability of the tool, but also ensures the lightweight characteristics of the tool. (4) Different surface treatment processes are used for the two different metal materials of the tool changer to ensure the wear resistance and corrosion resistance of the tool changer. The technical solution of the present invention can realize large-scale industrial production and meet the growing application market of robot tool changers. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is an exploded view of the robot-side tool changer of the present invention;

[0043] Figure 2 is an exploded view of a tool side tool changer of the present invention;

[0044] Figure 3 is a schematic diagram of a complete robotic tool changer of the present invention;

[0045] Figure 4 is a schematic diagram of a load-bearing component piston;

[0046] Figure 5 is a schematic diagram of a lock cylinder of a load-bearing component;

[0047] Figure 6 is a schematic diagram of the locking mechanism and the cross pin in the locking sleeve;

[0048] Figure 7 is a schematic diagram of a locking collar of a load-bearing component;

[0049] Figure 8 It is the force analysis diagram of the cross pin of the bearing mechanism component in a static state;

[0050] Fig. 9 It is a coupling diagram of the tool changer load-carrying tightening mechanism.

[0051] Among them, 1. tool changer body flange, 2. robot changer body, 3. tool locating pin, 4. pressure spring, 5. locating pin sealing ring, 6. piston sealing ring, 7. piston, 8. piston rod, 9. base sealing ring, 10. locking sleeve, 11. locking mechanism, 12. waist hole, 13. fastening bolt, 14. cross pin, 15. O-ring, 16. lock core fixing pin, 17. regular hexagonal lock core, 18. lock core fastening bolt, 19. tool side body, 20. tool side fastening bolt, 21. locking collar locating pin, 22. tool locating pin protective cover, 23. locking collar, 24. waist hole convex point, 25. cross pin annular groove, 26. opening for proximity switch with LED light. DETAILED DESCRIPTION

[0052] The technical solutions of various embodiments of the present invention will be described and illustrated below in conjunction with the accompanying drawings. The embodiments described and illustrated are part of the embodiments of the present invention, not all of the embodiments. In the technical description of the present invention, the positional relationship or orientation represented by terms such as "forward", "reverse", "vertical", "horizontal", "pushing out", "retracting", "up", "down", "inside", "outside", etc. is based on the positional relationship and orientation shown in the accompanying drawings. The purpose is to facilitate the description and explanation of the present invention, and it does not indicate or limit the specific positional relationship and orientation of the mechanism or component referred to. The positional relationship and orientation description in the invention do not constitute a limitation on the present invention. The well-known robot technical parameters, well-known mechanical principles and material tensile strength in the present invention do not belong to the limitations of the present invention. In addition, the "regular hexagon", "45°", "15°", "cross pin diameter" in the technical solution and the equations and mechanical data derived using the well-known mechanical principles are important technical parameters of the present invention. For those skilled in the art, the above terms belong to the technical features and important technical parameters of the present invention, and are an indispensable and important part of the present invention.

[0053] like Figure 1As shown, the bearing mechanism installed in the robot side tool changer body 2 has a locking sleeve 10, a single-acting piston cylinder, a piston 7, a regular hexagonal lock core 17 and six cross pins 14. The base of the locking sleeve 10 is circular, with a circular hole in the center. The diameter of the circular hole is consistent with the outer diameter of the piston cylinder 8. The regular hexagonal lock core 17 is connected to the piston 7 through the piston rod 8 and fixed with a bolt 18. The locking mechanism 11 of the locking sleeve 10 adopts a regular hexagonal structure, with a total of six waist holes 12 on it, which are used to install the cross pin 14. There is a convex point 24 at the center of the upper part of the waist hole 12, with a height of 1.5mm and a width of 1.5mm; the annular groove 25 in the middle of the cross pin is 2.0mm wide and 2.0mm deep. The gap between the cross pin 14 and the waist hole 12 is 0.2mm. The outer diameter of the cross pin 14 is designed to be 3 times the thickness of the hexagonal locking mechanism 11. The tool side changer body 19 is only equipped with a locking collar 23. An air intake channel is designed inside the changer body 2 on the robot side, and the air channel aperture is not greater than 1.5mm, which is directly connected to the bottom of the piston cylinder. The air channel of the changer body is connected to the external compression air by a quick connector. An exhaust channel is designed inside the changer on the robot side, and the opening is designed at the top of the piston cylinder to directly drive the piston 7. A sealing ring is installed at the top of the piston cylinder and the center hole of the lock core. When the external high-pressure gas is inhaled, the piston is driven to move in one direction, and the piston drives the lock core 17 to move in one direction. The lock core 17 pushes the six cross pins 14 out of the waist hole 12 of the locking sleeve 10 and abuts against the inner wall of the regular hexagonal inner hole of the locking sleeve ring. At this time, the tool changer completes the coupling and the end tool performs work. When the external high-pressure gas is exhausted, the regular hexagonal lock core 17 retracts, and the six cross pins 14 retreat to the center position of the waist hole 12, the tool changer is separated, and the end tool stops performing work or is replaced.

[0054] Protective measures when the tool changer is accidentally cut off: The single-acting piston cylinder is designed inside the tool changer body on the robot side and cooperates with the piston 7. 4-6 pressure spring inner grooves 4 are designed at the bottom of the piston cylinder, and the bottom of the piston 7 is also designed with a corresponding spring inner groove of the same size. The piston will be restricted by the pressure spring when moving. Even if the tool changer is accidentally cut off, the tool changer on the robot side will not fall off due to the effect of the spring pressure.

[0055] Detection measures for coupling and loosening of tool changers or separation of tools: Robot tool changers are all mechanical parts. Due to the manufacturing accuracy and installation deviation of the mechanical parts themselves, errors will be caused. In order to compensate for these errors, electrical control methods are used to detect the locking and loosening of the changer or the separation of tools. See attached Figure 3Three proximity switches 26 with LED lights are installed inside the robot side changer body. The detection distance of the proximity switch with LED lights is designed to be 1mm. Two detected objects are regular hexagonal lock cores 17, and one detected object is a locking collar 23. The LED lights use two colors, green and red. When the robot side changer is coupled with the tool side changer, the lock core 17 is in place and the distance is within 1mm, the LED light will display green; if the lock core is not in place and the distance is greater than 1mm, the corresponding LED light will display red. The two LED light proximity switches are installed in parallel with the lock core. One of the proximity switches with LED lights is installed vertically. The proximity switch is flush with the tool changer. When the tool side changer is coupled with the robot side changer, the proximity switch with LED lights displays green. When the tool side changer is separated from the robot side changer, the LED light displays red.

[0056] The tool changer adopts a split design, and the bearing mechanism components and the body are made of different metal materials. First, the preparation method of the bearing mechanism components is introduced. The preparation method of the bearing mechanism components is as follows: 1. The bearing mechanism components are a locking sleeve 10, a regular hexagonal lock core 17, a piston 7, 6 cross pins 14, and a locking collar 23. The bearing mechanism bears the load and dynamic torque of the end tool, and requires a metal material with high tensile strength. The blank is made of domestic precipitation hardened steel. Since the precipitation hardened steel blank cannot reach a tensile strength of 1200Mpa before heat treatment, according to the material hardness, the material hardness and the material tensile strength are equivalent. The hardness is converted into the international general standard, that is, the hardness of the load-bearing parts after heat treatment is required to be between 340-380HBS. The bearing mechanism components are finely processed at one time, and the dimensional tolerance is maintained between ±0.025mm. 2. Heat treatment of the bearing mechanism components, first quenching treatment, send the finished parts to the quenching furnace, heat to 850℃-900℃, then use heavy oil quenching, and then use tempering treatment, send the quenched finished parts to the tempering furnace and heat to 400℃-450℃, and finally use air cooling, the cooling time is 24 hours. Next, the finished parts are completely annealed, send the finished parts to the annealing furnace, heat to 650℃-700℃, keep warm for 8 hours, then slowly cool to 500℃, and then air cool; cool to room temperature. Natural aging of the finished parts, put a locking sleeve 10, a piston 7, a regular hexagonal lock core 17, 6 cross pins 14, and a locking collar 23 in the workshop for 48 hours, so that all the residual stress inside the parts is naturally released. After the natural aging of the finished parts is completed, the finished parts are cleaned. The oil and grease on the surface of the finished parts are cleaned with a weak alkaline solution, and then wiped clean with a non-woven cloth. Professional testing instruments are used to detect the mechanical properties of the load-bearing mechanism components. The hardness of the load-bearing mechanism components is between 340-380HBS, that is, the tensile strength is between 1080-1200Mpa. 3. The tolerance size of the load-bearing mechanism components. The components will be slightly deformed after heat treatment. In order to avoid the magnetism of the components during the secondary processing, the deformed parts of the components are ground with a grinder to ensure that the dimensional tolerance of the load-bearing mechanism components is maintained between ±0.025mm. 4. Surface chemical nickel plating treatment. Since industrial robots are used in aluminum electrolytic plants or aluminum foundries for new energy vehicles, under these working conditions, a hydrogen fluoride gas is precipitated from the aluminum solution during the aluminum melting process in the electrolytic cell or induction furnace. The molecular formula of hydrogen fluoride is FH, which is an acidic gas with extremely strong corrosiveness. The tool changer is a supporting tool for the robot. Under such working conditions, its surface is easily corroded. Although precipitation hardened steel itself has good corrosion resistance, it is still necessary to perform chemical nickel plating on the surface of the supporting mechanism components of the tool changer.Medium phosphorus high temperature nickel plating is used to chemically dip-plate all metal bearing mechanism parts in the liquid tank. The solution is 4.0-5.0g / L nickel sulfate heptahydrate, 25-30g / L sodium acetate, and the catalyst is sodium hypophosphite, with a concentration of 25-30g / L. A trace amount of fluoride salt is also required, which is added at a ratio of 8-12 g / L. Fluoride salt is commonly known as cryolite, and its molecular formula is Na3AlF6. It has been proven in practice that after cryolite is added to the nickel solution, the nickel coating has good wear resistance after drying. The pH value of the nickel solution is adjusted to between 4.5-5.0, the solution temperature is 85-90℃, the immersion time is 35-40min, the baking temperature is 150℃-160℃, and the baking time is 20-25 minutes. Rinse the parts with clean water for 5-6 minutes, wipe the surface of the parts clean, and after professional instrument testing, the thickness of the nickel plating is 10±2μm. The tool changer adopts a split design, and the preparation method of the tool changer body is as follows: 5. The body of the tool changer is a non-stress-bearing component. In order to meet the technical requirements of lightweight tools, the material of the body does not need to be the same as that of the bearing mechanism, and the tensile strength can be lower than that of the bearing mechanism components. According to the law of the use of dual alloy materials, the tensile strength ratio of the two materials is ≥1 / 2, and the tensile strength of the tool changer bearing mechanism component material is 1080-1200Mpa. It can be deduced that the tensile strength of the tool changer body material can be between 540-600Mpa. The tool changer body uses domestic low-carbon metal materials, and selects soft steel with a tensile strength between 540-600Mpa. The structure is a cube. The body of the tool changer is divided into two parts. The tool changer body on the robot side is manufactured first, and an external flange is designed on one working surface of the body. The flange diameter is selected according to the ISO9409-1 standard. The flange diameter is consistent with the flange inner diameter of the sixth axis of the industrial robot, and the flange thickness is designed to be 5mm. The robot body has a cavity inside, and needs to install a locking sleeve, a piston, a regular hexagonal lock core, and 6 cross pins. The size of the cavity matches the size of these parts. Install 3 spaces and channels with LED proximity switches on the robot body. Next, design the tool body, which also has a cavity structure inside. The tool body only needs to install a locking collar as a bearing component, and the size of the cavity matches the size of the locking collar. 6. The two parts of the tool changer body need to be surface treated, and anodizing is used to increase the hardness of the tool body surface. In order to enhance the corrosion resistance of the tool changer surface, the coating thickness of the tool changer body is 50±5μm, and the hardness is controlled between 340-380HBS, which is consistent with the hardness of the bearing component. The color of the tool changer body remains the natural black-brown color of anodizing.

[0057] The tool body on the robot side is equipped with two locating pins, and the tool body on the tool side is equipped with two corresponding pin holes. The tool body on the robot side is semi-permanently connected to the robot's sixth axis or end flange with 6 12.9-grade bolts, and the tool changer on the tool side is fixed to the end tool. Three proximity switches with LED lights are connected to the robot's electrical control system, and other necessary auxiliary facilities are connected to the robot control system. The robot controller and the electrical control system work together to drive the coupling, loosening or separation of the tool changer.

[0058] The above-mentioned embodiments describe several implementation methods of the present invention, and some technical parameters are described in detail and truthfully, but they cannot be understood as limiting the scope of the patent of the present invention. It should be noted that for those skilled in the art, without creative work, some improvements and changes made based on the technical parameters, mathematical equations and mechanical data, and geometric shapes of the tool changer of the present invention should be included in the protection scope of the present invention application. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. The robot tool changer adopts a cube structure, which is divided into a robot side main plate and a tool side sub-plate. The robot side main plate is semi-permanently fixed on the flange of the robot's sixth axis, and the tool side sub-plate is connected to the end tool. The tool changer body on the robot side and the tool side body are designed as a cavity structure. The components of the bearing mechanism are designed according to the specifications and dimensions of the cavity structure of the tool changer body, respectively installed inside the body cavity, and fixed or connected together with bolts. The bearing mechanism components are 1 locking sleeve, 1 regular hexagonal lock core, 1 piston, 6 cross pins, and 1 locking collar. The bearing mechanism bears the load and dynamic torque of the end tool, and requires a metal material with high tensile strength. The blank is made of domestic precipitation hardened steel. After heat treatment, the tensile strength of the bearing mechanism components is between 1080-1200Mpa. The tool changer body is two parts, using domestic low-carbon metal materials, and selecting soft steel with a tensile strength between 540-600Mpa. The structure is a cube. First, design the various components of the bearing mechanism. Design a geometric piston cylinder inside the tool body on the robot side. The body is equivalent to the outer wall of the piston cylinder. The intersection of the two diagonals on a working surface of the body is used as the center of the piston cylinder. The inner diameter of the piston cylinder is the same as the inner diameter of the robot's sixth axis or end flange. Since the global robot flange adopts the ISO9409-1 standard, the inner diameter of the piston cylinder can be obtained based on the inner diameter of the robot's sixth axis or end flange. Correspondingly, a piston is designed. The outer diameter of the piston is the same as the inner diameter of the cylinder body. The piston is driven unidirectionally in the geometric cylinder body of the robot side body to form a single-acting piston cylinder. The stroke of the piston rod can be calculated based on the constraint relationship between the piston pressure and the bearing mechanism. Design a locking sleeve. The sleeve base is designed to be circular, and the locking mechanism is designed to be a regular hexagon. The sleeve base and the locking mechanism are designed as an integrated design. A waist hole is designed at the center of each regular hexagonal locking mechanism, and a corresponding cross pin is designed at the same time. The specifications and sizes of the cross pin are the same, and the specifications and sizes of the cross pin and the waist hole are matched. A gap of 0.2mm is reserved between the cross pin and the waist hole. The outer diameter of the cross pin is designed to be 3 times the thickness of the hexagonal locking mechanism. The cross pin adopts a circular structure, and an annular groove is designed in the middle. A convex point is designed at the upper center of the waist hole. The cross pin is installed in the waist hole. Due to the blocking effect of the convex point, the cross pin is fixed in the middle of the waist hole and will not completely separate from the waist hole. The six cross pins and the six locking mechanisms of the locking sleeve together constitute the tool changer and the end tool bearing mechanism. A regular hexagonal lock core is designed. In order to increase the bearing capacity of the lock core, the lock core is designed as a double-layer structure, and the taper of the six sides of the lock core is designed to be 15°. A circular hole is designed in the center of the locking sleeve. The diameter of the circular hole is consistent with the outer diameter of the piston rod. The piston rod passes through the center hole of the sleeve and is connected to the lock core with bolts. Six bolt holes are designed on the annular seat of the locking sleeve and fixed to the main body on the robot side with bolts.Design a locking collar with a hollow design, a hole in the middle, and a regular hexagonal structure in the inner hole. The inner angle is 45°, and the outer diameter of the locking collar is the same as the outer diameter of the locking sleeve base. The locking collar is installed in the tool side body of the changer and fastened to the tool side body with 6 bolts. The robot side changer body is designed with air intake and exhaust channels. When the piston cylinder is inhaled, the gas drives the piston, driving the lock core to move in one direction. The lock core pushes the six cross pins out of the waist hole of the locking sleeve and rests on the six inner sides of the tool side locking collar. The tool changer is coupled and the end tool does work. At this time, it is equivalent to six levers jointly bearing the load and torque of the end tool. The six cross pins are in a coplanar state when the tool changer is coupled, and the tool changer and the end tool are on the same force surface, which ensures the flatness of the full set of tool changers. When the single-acting piston cylinder is exhausted, the regular hexagonal lock core retracts. Due to the reverse friction, the six cross pins return to the center of the waist hole, the tool changer separates, and the end tool stops working or is replaced. The tool changer made using the lever principle and cross pin structure has six times the load and torque of the ball lock tool changer of the same specification and diameter. In the static state, the load and torque of the bearing mechanism can be calculated based on the static equilibrium equation, so that tool changers with different loads and torques can be made according to the load and torque requirements.

2. Design a geometric piston cylinder inside the tool body on the robot side. The body is equivalent to the outer wall of the piston cylinder. The intersection of the two diagonals on a working surface of the body is used as the center of the piston cylinder. The inner diameter of the piston cylinder is the same as the inner diameter of the robot's sixth axis flange. Since the global robot flange adopts the ISO9409-1 standard, the inner diameter of the piston cylinder can be obtained based on the inner diameter of the robot's sixth axis flange. A piston is designed accordingly. The outer diameter of the piston is the same as the inner diameter of the cylinder body. The piston is driven unidirectionally in the geometric cylinder body of the robot side body to form a single-acting piston cylinder. The stroke of the piston rod can be calculated based on the constraint relationship between the piston pressure and the bearing mechanism. Three proximity switches with LED lights are installed inside the robot side changer body. The detection distance of the LED light detection switch is set to 1mm to detect the locking, loosening or separation of the tool changer.

3. The tool changer according to claim 1 is of split design and made of dual alloy material. It is characterized in that The bearing mechanism blank is made of domestic precipitation hardened steel. After heat treatment, the tensile strength of the bearing mechanism components is between 1080-1200Mpa. The tool changer body is two parts, which are characterized by the use of domestic low-carbon metal materials, soft steel with a tensile strength between 540-600Mpa, and a cube structure.

4. The design of the tool changer carrier mechanism component according to claim 1 is characterized in that The locking mechanism of the locking sleeve is designed to be a regular hexagon, the lock core is designed to be a regular hexagon, the taper of the six sides is designed to be 15°, the inner hole of the locking ring adopts a regular hexagon structure, and the inner angle is 45°.

5. According to claim 1, the sleeve base of the bearing mechanism is designed to be circular, and the locking mechanism is designed to be a regular hexagon, characterized in that A waist hole is designed at the center position of each regular hexagonal locking mechanism, and a corresponding cross pin is designed at the same time. The specifications and dimensions of the cross pins are the same and match the waist hole. A gap of 0.2mm is reserved between the cross pin and the waist hole. The outer diameter of the cross pin is designed to be 3 times the thickness of the hexagonal locking mechanism. The cross pin adopts a circular structure, which is characterized in that an annular groove is designed in the middle of the cross pin and a convex point is designed at the upper center position of the waist hole. The height of the convex point is 1.5mm and the width is 1.5mm; the width of the annular groove in the middle of the cross pin is 2.0mm and the depth is 2.0mm.

6. Design a piston cylinder inside the robot body cube. The inner diameter of the piston cylinder is the same as the inner diameter of the robot's sixth axis flange. Since the inner diameter of the single-acting piston cylinder is the same as the outer diameter of the piston, the outer diameter of the piston can be determined after the inner diameter of the piston cylinder is determined. After determining the outer diameter of the piston, design the diameter of the piston rod. According to the design principle of the piston, the diameter ratio d / D of the piston rod to the piston is between 0.2 and 0.

4. The factory compressed air is between 0.40 and 0.7Mpa, the actual pressure P0 is generally 0.5Mpa, and the efficiency η of gas compression is generally 0.

85. According to the "Mechanical Design Manual" and the actual situation of the factory, the pressure P of the single-acting piston cylinder is calculated, and the theoretical pressure P of the single-acting piston cylinder is calculated through mathematical modeling. P=π / 4(D 2 -d 2 )P0η P0=0.5MPa η=0.85 P=π / 4(D 2 -d 2 )0.5×0.85N=0.334(D 2 -d 2 )N 7. The locking sleeve, piston, regular hexagonal lock core, cross pin and locking collar are combined into a load-bearing mechanism, and the cross pin is the most important component of the load-bearing mechanism. As a dynamic tool, the tool changer must be connected to the sixth axis of the industrial robot through bolts to do work. In a static state, the resultant force of the cross pin in the three directions of the X-axis, Y-axis and Z-axis is zero respectively; under static conditions, the tool changer analyzes the stress state of the cross pin, the regular hexagonal lock core and the locking collar, and calculates the mechanical data of the load-bearing mechanism through mathematical modeling. The pressure of the single-acting piston cylinder is P, the diameter of the cross pin is R, and the number is 6. Ignoring the uneven force state of the cross pin, the axial balance equation of the pin core in the load-bearing mechanism is: 6(F n2 sinβ-F t2 cosβ)=P (1) 8. The cross pin is installed inside the robot tool changer. According to the principle of statics, the sum of the forces in the three directions of the X-axis, Y-axis and Z-axis is 0. For details, see the force analysis state of the cross pin in Figure 7. The static equilibrium equation of the cross pin is given by ∑F x =0,∑F y =0,∑M B1 =0 to obtain the following mathematical equation. The combined equations (1) and (2) can be transformed by trigonometric functions to obtain: In the above equation, P is a constant, the value of α is 45°, and the value of β is 15°. The data of Fn, Ft2, Fn1, and Fn2 are calculated respectively. Mathematical modeling is used to perform theoretical calculations on the mechanical data of the load-bearing mechanism. When the inner angle of the locking collar is 45° and the taper value of the regular six-shaped deformation lock core is 15°, the equation takes the maximum value, indicating that the force on the cross pin is at the maximum state, the diameter of the cross pin increases, and the load-bearing capacity also increases accordingly.

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