Automatic screw assembling mechanism

Abstract

The application relates to the technical field of automation equipment, in particular to a screw automatic assembling mechanism, which comprises a three-axis robot, a linear driving device is fixedly installed on one movable sliding block of the three-axis robot, an electric screwdriver is fixedly installed on the linear driving device, a batch head is arranged on the electric screwdriver, the batch head is arranged as a combined batch head, a guide hole is arranged in the batch head, and a jacking rod is slidably installed in the guide hole. The power unit and the fixing unit are installed in the batch head, when the power unit drives the jacking rod, the vertical movement of the jacking rod is converted into the horizontal movement of a top block, the static friction between the top block and the screw is generated, the batch head can stably grab the screw for a long time, the screw assembling mechanism is suitable for occasions where the depth of countersunk head screws is large, and the application range of the screw automatic assembling structure is increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automation equipment, in particular to a screw automatic assembly mechanism. BACKGROUND

[0002] At present, the screw automatic assembly mechanism is generally composed of a screw clamping part, a three-axis robot and an electric screwdriver. Among them, the screw clamping part has three types: linkage clamping, magnet and vacuum adsorption, and the part directly contacting with the screw is the clamping nozzle. The working process of the existing screw automatic assembly mechanism is generally as follows: the screw clamping part fixes the screw output by the screw conveyor in front of the electric screwdriver, then the three-axis robot moves the screw clamping part and the electric screwdriver to the corresponding position of the workpiece screw hole, so that the screw is away from the coaxial screw hole by 3-5 mm, and then the linear driving device drives the electric screwdriver to move towards the screw. After the electric screwdriver cooperates with the screw, it starts to rotate the screw and rotates the screw into the screw hole. The screw depth detection device and the torque detection device monitor the rotation depth and torque of the screw, and once the set value is reached, the electric screwdriver will stop rotating. Then, the three-axis robot moves the screw clamping part and the electric screwdriver to start the next screw assembly cycle.

[0003] However, the existing electric screwdriver cannot clamp the screw when it faces the screw that cannot be magnetized, such as 304 stainless steel screw and aluminum alloy screw. The chuck does not have the function of clamping the screw. The chuck usually drives the screw out of the clamping nozzle by impact force and drives the screw to move a short distance, and then enters the screw hole. However, when facing a deep counterbore, the diameter of the counterbore is generally slightly larger than the maximum diameter of the screw, and the clamping nozzle needs to completely wrap the screw, so its volume is larger than the diameter of the counterbore, so the clamping nozzle cannot enter the hole, resulting in that the electric screwdriver needs to drive the screw to move a long distance. The existing chuck cannot clamp the screw, so it cannot guarantee that the screw enters the screw hole vertically, resulting in that the screw automatic assembly mechanism is prone to slip and float lock when facing such situation, and the current solution is to complete the assembly of the screw by artificial.

[0004] In view of this situation, a new screw automatic assembly mechanism is proposed, which installs a power unit and a fixing unit in the chuck, triggers the fixing unit through the power unit, so that the chuck can stably clamp the screw for a long time, and the screw assembly mechanism is suitable for deep counterbore screw occasions, and the application range of the screw automatic assembly structure is increased. SUMMARY

[0005] The screw automatic assembly mechanism is characterized in that: a power unit and a fixing unit are arranged in the chuck; when the power unit drives the ejector rod, the vertical movement of the ejector rod is converted into the horizontal movement of the fixing unit, so that the fixing unit and the screw generate continuous static friction, the chuck can stably grab the screw for a long time, the screw assembly mechanism is suitable for occasions where the countersunk head screw is deep, and the application range of the screw automatic assembly structure is increased.

[0006] To achieve the above object, the present application provides the following technical scheme:

[0007] A screw automatic assembly mechanism comprises:

[0008] A three-axis robot, one movable slide of the three-axis robot is fixedly provided with a screw clamping part, the screw clamping part is provided with a clamping nozzle, the movable slide is fixedly provided with a linear driving device, the linear driving device is fixedly provided with an electric screwdriver, the electric screwdriver is provided with a chuck, and the chuck is located directly above the clamping nozzle.

[0009] The chuck is a combined chuck, the chuck is provided with a guide hole, the guide hole is slidably provided with an ejector rod, the chuck is provided with a power unit for driving the ejector rod to move up and down, the power unit can linearly move synchronously with the chuck, the power unit will not hinder the rotation of the chuck, the bottom end of the chuck is provided with a fixing unit for stably fixing the screw, and when the ejector rod cannot continue to move downward under the reaction force of the fixing unit, the fixing unit locks and fixes the screw.

[0010] The existing screw automatic assembly mechanism generally comprises a three-axis robot, a screw clamping part and an electric screwdriver. The three-axis robot is used for adjusting the positions of the screw clamping part and the electric screwdriver, so as to realize the grabbing and assembly of the screw. The screw clamping part is generally divided into linkage clamping, magnetic attraction and vacuum adsorption, the screw is clamped by the clamping nozzle, moved to the front of the screw hole by 3-5 mm, and made parallel to the axis of the screw hole, so as to assist the electric screwdriver to rotate the screw into the screw hole. The electric screwdriver is used for ejecting the screw from the screw clamping part, then moving into the screw hole, and rotating the screw, so that the screw can be completely assembled into the screw hole. Meanwhile, the screw automatic assembly mechanism is also provided with a torque detection device, a depth detection device and a linear driving device, the linear driving device is used for moving the electric screwdriver, and the torque detection device and the depth detection device are used for detecting whether the screw is assembled in place.

[0011] Because the current electric screwdriver does not have the function of clamping the screw when it faces the screw that cannot be attracted by the magnet. It usually drives the screw to move a short distance by impact force, and then enters the screw hole. However, when facing a deep countersunk hole, the screw clamping part is too large to enter the hole, so the electric screwdriver needs to drive the screw to move a long distance. The existing chuck cannot guarantee that the screw enters the screw hole vertically, so the existing screw rotating assembly mechanism cannot guarantee that the screw is parallel to the axis of the screw hole when the screw enters the screw hole, so it is easy to appear slip and float lock. The existing solution is to complete the assembly of the screw in this case by artificial. In addition, when the screw automatic assembly equipment detects that the screw assembly appears slip or float lock, the chuck can be reversed to disassemble the screw, but it cannot take out the screw from the countersunk hole, so the worker needs to spend a lot of time to take out the failed screw when checking and repairing, which affects the work efficiency.

[0012] Therefore, the power unit and the fixing unit are installed in the chuck, and the linear driving device and the depth sensor cooperate. When the linear driving device drives the electric screwdriver to move to the chuck and the screw is fully engaged, the power unit starts to push the ejector rod to start the fixing unit to fix the screw by the chuck. When the fixing unit is fully started, the linear driving device continues to run to drive the electric screwdriver and the screw to move forward. The linear driving device here is generally a lead screw mechanism, an electric push rod and a linear motor, etc. At the same time, after the screw automatic assembly mechanism assembles the screw, if the torque detection device and the depth detection device find that the screw is not assembled in place, the electric screwdriver can be reversed by the control system to disassemble the screw from the screw hole. Before the electric screwdriver is reversed, the power unit starts the fixing unit through the ejector rod to make the chuck clamp the screw. When the screw automatic assembly mechanism disassembles the screw, the three-axis robot moves the chuck away from the screw hole, so that the chuck can take away the failed screw, which is convenient for the subsequent detection and maintenance of the workpiece by the worker. The present application can be applied to internal hexagonal screws and other screws with large fixed slots, but cannot be used for cross-slots, one-slot and other small slots.

[0013] The present application sets the batch head as a combined batch head, which is composed of four parts. The first batch head is connected with the automatic screwdriver, the second batch head is provided with a driving unit, and the fourth batch head is provided with a fixing unit. Each part is detachably connected and assembled to realize modularization and facilitate the assembly of the power unit and the fixing unit. Since the most easily worn area of the batch head is the part matched with the screw, the general batch head needs to be replaced when this part is excessively worn, otherwise the batch head cannot tighten the screw. The modularization of the batch head can replace only the worn fourth batch head, reduce the replacement of other batch heads, power units and fixing units, and reduce the cost of production equipment. The length of the third batch head is equal to the maximum stroke of the driving unit that can follow the linear movement of the batch head, and the first batch head is used to ensure stable connection with the electric screwdriver. Of course, the number of segmented combined batch heads can be increased or decreased on this basis, and can be selected according to actual conditions.

[0014] Preferably, the power unit comprises a guide cylinder fixedly installed on the movable slider, and the guide cylinder is coaxial with the batch head. A guide groove is formed in the side wall of the guide cylinder, a sleeve is slidably installed on the guide groove, the sleeve is rotatably installed on the batch head, a positioning member for linear movement of the sleeve following the batch head is installed on the batch head, a first space and a second space are respectively formed in the inner side wall of the sleeve, the first space and the second space are connected with gas pipes, a movable groove is formed in the end of the guide hole close to the electric screwdriver, a piston is slidably installed in the movable groove, one side of the piston is fixedly connected with a jacking rod, the end of the movable groove away from the electric screwdriver is provided with a through hole one closely combined with the jacking rod, the batch head is respectively provided with a first gas hole and a second gas hole corresponding to the first space and the second space, and the first gas hole and the second gas hole are in communication with the movable groove, the first gas hole and the second gas hole are divided into two sides of the piston, and the movable groove is provided with a protrusion for avoiding the piston from blocking the first gas hole.

[0015] The guide cylinder is used to limit the rotation of the sleeve and to guide the sleeve to only linearly move, so the length of the guide cylinder is greater than the moving distance of the screw. When the linear drive device drives the electric screwdriver to the fourth head to cooperate with the screw, the gas pipe sends gas into the first space, the gas enters the movable groove from the first gas hole, and pushes the piston to move in the direction close to the third head, the piston drives the top rod to move synchronously, so as to start the fixed unit. When the screw is installed in place or the screw contacts the screw hole to prepare to start assembly, the gas pipe stops sending gas into the first space, and starts to send gas into the second space, the gas enters the movable groove through the second gas hole, and pushes the piston to move in the direction close to the first head, while the top rod moves synchronously with the piston, when the piston contacts the protrusion, the piston stops moving, and the fixed unit is closed. Since the sleeve can linearly move with the second head, but cannot rotate with the second head, therefore, no matter how the second head rotates, the first gas hole and the second gas hole are always located in the first space and the second space. The through hole is provided with a sealing ring to increase the air tightness between the top rod and the movable groove. The protrusion can prevent the piston from blocking the first gas hole when the piston moves in the direction close to the first head, so that the power unit fails in subsequent use. The positioning member can be an elastic ring, a pin or a screw.

[0016] The power unit can also drive the piston by using hydraulic pressure instead of gas pressure. Compared with gas pressure drive, hydraulic drive transmission is more stable, and the piston can be self-lubricated, prolonging the service life of the piston and reducing the cost and time of maintenance. However, since the existing automatic screw assembly mechanism is generally equipped with a gas pressure system for conveying and clamping screws, driving by gas pressure does not need to increase the pump body additionally, while driving by hydraulic pressure needs to be equipped with a new hydraulic system, which is more expensive. The actual situation can be selected.

[0017] The inner hexagonal hole of the inner hexagonal screw is generally slightly larger than half of the diameter of the screw. For example, the size of the inner hexagonal hole of the M6 inner hexagonal screw is usually between 3.05mm-3.2mm. The gap between the corresponding inner hexagonal wrench and the inner hexagonal hole is generally 0.05mm-0.1mm, so the diameter of the guide hole and the top rod can be at least 0.2mm, but in order to ensure the strength of the top rod, the diameter of the guide hole and the top rod is at least 1mm, so the cross-sectional area of the head is reduced by 10%, and the torque resistance of the head is reduced by 10%. The maximum torque that a 3.2mm head can withstand is 32N·m, while the maximum torque that the head of the present application can withstand is 28.8N·m, and the tightening torque of the M6 inner hexagonal screw is generally 5-10N·m, so the present application will not affect the normal work of the head. The diameter of the second head is generally twice the diameter of the fourth head, so the diameter of the movable groove and the piston of the present application can be at most 1 / 3 of the diameter of the second head.

[0018] Preferably, the first gas hole and the second gas hole are staggered along the head axis.

[0019] The first and second air holes are arranged alternately around the axis of the second batch of heads, preferably with an interval of 180°, since the air holes and the movable slots on the second batch of heads reduce the bending strength of the second batch of heads, the alternate arrangement of the air holes can avoid too much reduction of the bending strength in the same direction, and ensure the service life of the second batch of heads. However, at the same time, since the sleeve of the present application closely fits on the second batch of heads, and the sleeve itself has a certain bending strength, the sleeve can make up for part of the bending strength of the second batch of heads, so that the screw automatic assembly mechanism can be used normally.

[0020] Preferably, the guide hole is provided with a threaded groove at one end close to the movable slot, and the threaded groove is located below the through hole, the top rod is provided with a thread matched with the threaded groove, and the lead angle of the thread is greater than ten degrees.

[0021] Compared with direct translation, the object translation is subjected to smaller resistance. In the direct translation process, every mass point of the object is subjected to the action of resistance, so that more energy needs to be consumed to overcome friction and resistance. In the object spiral translation, due to the flexibility of the piston, the movement of the object can be gradually pushed through rotation, which reduces the relative movement speed, reduces the friction and resistance, and thus consumes less energy.

[0022] Therefore, the threaded groove is provided at one end of the guide hole close to the movable slot, and the threaded groove is located below the through hole, the top rod is provided with a thread matched with the threaded groove, and the lead angle of the thread is greater than 10°. When the lead angle is greater than or equal to 10 degrees, the proportional relationship between the axial pushing force of the top rod and the rotational torque changes, resulting in an increase in the torque of the top rod rotation, and the top rod is easy to rotate. In this case, when the air pressure pushes the piston to move, the cooperation between the threaded groove and the thread will make the piston and the top rod rotate while translating, reducing the resistance of the top rod and the piston when moving, reducing the probability of the top rod bending due to the gap between the top rod and the guide hole, reducing the wear of the top rod and the guide hole, and prolonging the service life of the top rod. At the same time, in order to prevent the top rod from being twisted and deformed when rotating, the top rod is made of high-strength and high-hardness material, such as aluminum alloy, 45 steel, etc. At the same time, in order to ensure the air tightness of the moving space, the threaded groove is arranged below the through hole.

[0023] Preferably, the fixing unit comprises two through holes two symmetrically provided on the head away from the electric screwdriver, each of the through holes two is communicated with the guide hole, and each of the through holes two is slidably provided with a top block, one end of the top block close to the guide hole is hemispherical, one end of the top rod close to the top block is hemispherical, and the head is provided with a reset unit for automatically storing the top block in the through hole two.

[0024] When the power unit pushes the ejector rod through the piston to contact the top block and continues to move forward, the ejector rod pushes the top block to move away from each other, so that the top block will extend outside the second through hole and resist the inner side wall of the internal hexagonal hole, and a certain friction force is generated between the top block and the screw. At this time, the ejector rod cannot continue to move, thereby realizing the function of stably clamping the screw by the fourth head. The semispherical shape on the ejector rod and the top block can change the transmission direction by 90°, and is not easy to be damaged. After the screw is assembled in place, the piston drives the ejector rod to reset. At this time, the ejector rod has no supporting force, and the friction force between the top block and the side wall of the internal hexagonal hole is reduced. At this time, the head cannot fix the screw, and when the head separates from the screw under the action of the linear driving device, the friction force between the top block and the internal hexagonal hole makes the top block enter the second through hole. The stroke of the top block should be greater than 1 / 2 of the gap between the fourth head and the internal hexagonal hole, so as to well realize the clamping of the screw by the top block. The minimum stroke of the top block of the present application is 0.5mm, which is much larger than the gap of 0.05mm-0.1mm between the fourth head and the internal hexagonal hole. The cross-sectional area of the top block is greater than the maximum cross-sectional area of the semispherical body. In order to ensure the strength of the fourth head, only one set of second through hole and top block is used in the present application.

[0025] In addition to providing the semispherical body for transmission of the fixed unit, the inclined slide block can also be used for transmission of the fixed unit. Compared with the transmission mode of the semispherical body, the processing difficulty of the inclined slide block is lower, and the production cost is lower. However, the acute angle of the inclined slide block is small in thickness, and is easy to deform, which leads to failure of the fixed unit, so the service life of the inclined slide block is lower. The actual situation can be selected.

[0026] Preferably, the second through hole is inclined downward, the included angle between the second through hole and the horizontal plane is thirty degrees, and the end face of the top block away from the sphere is parallel to the outer side wall of the head opening the second through hole.

[0027] When the ejector rod moves downward under the action of the driving unit, since the line connecting the spherical center of the top block semispherical body and the spherical center of the ejector rod semispherical body is the force direction between the ejector rod and the top block, this direction changes all the time with the downward movement of the ejector rod. If the ejector rod is installed horizontally, the initial force direction between the top block and the ejector rod and the moving direction of the ejector rod form an included angle of 60°. At this time, most of the thrust of the ejector rod will be converted into the pressure of the top block to the side wall of the second through hole, which leads to increased wear between the top block and the second through hole, and reduced service life of the top block. Therefore, the second through hole is inclined in the present application, so as to reduce the included angle between the force direction between the top block and the ejector rod and the moving direction of the top block, thereby reducing the wear between the top block and the second through hole. However, if the included angle between the second through hole and the horizontal plane is 60°, the force direction between the top block and the ejector rod and the moving direction of the ejector rod are completely the same at the beginning. However, when the ejector rod moves to the lowest position, the force direction between the top block and the ejector rod and the moving direction of the ejector rod still form an included angle of 60°. Therefore, the inclination angle is set to 30°, which can reduce the maximum pressure of the top block to the second through hole by 50%.

[0028] Meanwhile, in order to ensure that the contact between the top block and the screw is surface-to-surface, the end of the top block away from the hemisphere is set as an inclined surface, so that the end face of the top block away from the hemisphere is parallel to the outer wall of the second through hole of the bit. The area of ​​the inclined surface is larger than the cross-sectional area of ​​the top block, which increases the contact area between the top block and the screw and improves the stability of the fixing unit for the screw.

[0029] Preferably, the end of the guide hole away from the electric screwdriver is provided with a spherical groove, and the radius of the spherical groove is equal to the radius of the hemispherical part of the push rod.

[0030] Due to wear during use, the length of the ejector block will decrease, thus increasing the stroke required for it to press against the screw's internal hexagonal socket. The maximum stroke of the ejector block is half the diameter of the ejector pin. Therefore, to fully utilize the ejector block, the fourth bit should only be replaced after it has worn to its maximum length. A spherical groove can be provided at the end of the guide hole furthest from the third bit, with the radius of the groove equal to the radius of the ejector pin's hemisphere. This allows the ejector pin's hemisphere to fully enter the groove, preventing machining errors from preventing the vertical part of the ejector pin from contacting the ejector block's hemisphere. When the ejector pin contacts the spherical groove, the ejector block moves to its maximum limit position. For ease of operation, the wear level of the ejector block needs to be checked each time the automatic screw assembly mechanism is used. This is done by adding gas to the first space to ensure the ejector pin fully enters the spherical groove. If the ejector block is found to be flush with the outer wall of the fourth bit at this point, it indicates that the ejector block has failed and needs to be replaced.

[0031] Preferably, the reset unit includes a hemispherical portion of the push rod made of magnetic material, a hemispherical portion of each top block made of a magnetically attractable material, and the push rod always in contact with the top block. The cross-sectional shape of the second through hole is a non-rotational body, the cross-sectional shape of the non-spherical portion of the top block is a non-rotational body that matches the second through hole, and the connection between the second through hole and the guide hole is a circular hole with a diameter equal to that of the hemispherical portion of the top block.

[0032] The hemispherical portion of the top block is made of a magnetically attractive material, such as an iron-cobalt-nickel alloy, while the hemispherical portion of the top rod is made of a magnetic material, such as a neodymium iron boron magnet, ferrite magnet, or AlNiCo magnet. Each time the top rod moves upward under the action of the power unit, the magnetic attraction between the top rod hemisphere and the top block hemisphere pulls the top block into the second through hole. This prevents friction between the top block and the screw when the bit is tightening or loosening the screw, extending the lifespan of the top block. Simultaneously, the bit of this invention needs to be made of non-magnetically attractive materials such as 304 stainless steel and aluminum alloy to avoid interfering with the top block. For strength and wear resistance reasons, the part of the top block that contacts the screw needs to be made of a wear-resistant material; therefore, magnetic materials can only be used in the hemispherical portion. To prevent the magnetic strength between the top rod and the top block from weakening due to the gap, a limiting protrusion in the movable groove ensures that the top rod is always in contact with the top block.

[0033] To reduce friction between the top block and the second through hole, and to prevent the top block's cross-sectional area from decreasing, which would increase pressure when the top block presses against the internal hexagonal hole and cause damage to both, this invention sets the second through hole to a non-rotating shape and sets the top rod to a matching shape. This ensures that only relative displacement friction occurs between the top block and the second through hole, without relative rotational friction. To prevent the non-hemispherical portion of the top block from entering the guide hole, which would prevent the top block from moving away when it acts on this part, causing the fixing unit to fail, a limiting protrusion is provided in the second through hole. The limiting protrusion has a circular through hole that allows the hemisphere to move. Therefore, the diameter of the through hole is equal to the diameter of the hemisphere. Since the maximum side length of the top block is greater than the diameter of the hemisphere and the top block is non-rotating, the remaining part of the hemisphere will be blocked by the limiting protrusion.

[0034] Preferably, the end of the top block away from the top rod is provided with an elastic material to increase friction, and the elastic material is compressed and deformed when the top rod moves down to the limit position, thereby increasing the contact area with the screw.

[0035] To increase the static friction between the push block and the screw, an elastic material, such as rubber, styrene-butadiene rubber, or polyurethane, is placed at the end of the push block furthest from the hemisphere to increase friction. Simultaneously, when the push rod pushes the push block closer to the screw, the push block and screw compress the elastic material, deforming it and increasing the contact area between them to be larger than the end face area of ​​the push block, thus improving the stability of the push block in fixing the screw. However, the elastic material outside the push block's end face projection does not experience direct contact with the push block's thrust, so the pressure on the screw gradually decreases as it moves away from the push block. This leads to a decrease in friction between the elastic material and the screw further away from the push block, and the decrease in friction is negatively correlated with the strength of the elastic material. Therefore, the elastic material can be selected based on the specific circumstances.

[0036] Preferably, the top block and the second through hole are in a transition fit, and when the top rod moves upward, the space between the top blocks forms a negative pressure that pulls the top blocks to move closer to each other.

[0037] Because the movement of the top block is hindered by gravity and friction, the magnetic attraction between the top rod and the top block alone may not be sufficient to reset the top block if it becomes misaligned and stuck. Therefore, this invention sets the second through hole and the top block as a transition fit, and with the lubricating oil inside the second through hole, a relatively sealed environment is formed between the guide hole and the outside. Thus, when the top rod moves upward, the volume of the guide hole increases, causing the air pressure inside the guide hole to be lower than the standard atmospheric pressure. Therefore, the external air pressure assists in pushing the top block towards the top rod, ensuring the stable operation of the fixing unit.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. By installing a power unit and a fixing unit inside the screwdriver bit, when the linear drive device moves the electric screwdriver until the bit is fully engaged with the screw, the power unit converts the vertical movement of the push rod into the horizontal movement of the fixing unit. This generates continuous static friction between the fixing unit and the screw, allowing the screwdriver bit to stably grip the screw for a long time. When facing deep countersunk holes, the screwdriver bit can drive the screw to enter the screw hole in a direction parallel to the screw hole axis, reducing stripping and locking when assembling deep countersunk screws, improving the screw assembly pass rate, and increasing the applicability of the automatic screw assembly mechanism.

[0040] 2. When the torque detection device and depth detection device detect that the screw is not properly assembled, the power unit drives the push rod, which converts the vertical movement of the push rod into the horizontal movement of the fixed unit. This generates a continuous static friction force between the fixed unit and the screw, allowing the screwdriver bit to stably grip the screw. Combined with the reverse rotation of the electric screwdriver, the faulty screw can be removed from the screw hole. This reduces the time that workers need to manually remove faulty screws when inspecting and repairing stripped threads or floating locks, thus improving the efficiency of the workers' repair work.

[0041] 3. By arranging the fixing unit at an angle, the angle between the force direction and the movement direction of the top block is reduced when the vertical movement of the top rod is converted into the horizontal movement of the top block. This reduces wear on the top block and extends its service life. Simultaneously, the top block's cross-section is set as an inclined plane, ensuring face-to-face contact between the top block and the screw. The inclined plane of the top block has a larger area than its cross-sectional area, thus increasing the stability of the fixing unit for screw fixation. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0043] Figure 2 forFigure 1 Enlarged view of a portion of point A in the middle;

[0044] Figure 3 This is a schematic diagram of the electric screwdriver structure of the present invention;

[0045] Figure 4 for Figure 3 BB section view;

[0046] Figure 5 for Figure 4 Enlarged view of a section at point C;

[0047] Figure 6 This is a schematic diagram of the push rod of the present invention moving to its limit position;

[0048] Figure 7 for Figure 4 Enlarged view of a section at point D;

[0049] Figure 8 This is a schematic diagram of the fixed unit triggering according to the present invention:

[0050] Figure 9 This is a schematic diagram of the internal structure of the fourth batch head of the present invention;

[0051] Figure 10 This is a schematic diagram of the working process of the present invention.

[0052] In the diagram: 1. Three-axis robot; 101. Movable slider; 2. Screw clamping part; 201. Clamping mouth; 3. Linear drive device; 4. Electric screwdriver; 5. Screwdriver bit; 501. First bit; 502. Second bit; 503. Third bit; 504. Fourth bit; 6. Guide hole; 7. Push rod; 8. Power unit; 801. Guide cylinder; 802. Sleeve; 803. Positioning component; 8041. First space; 8042. Second space; 805. Air supply pipe; 806. Movable groove; 807. Piston; 8081. First air hole; 8082. Second air hole; 809. Protrusion; 9. Fixing unit; 901. Push block; 1001. Through hole one; 1002. Through hole two. Detailed Implementation

[0053] The following will be combined with the appendix of the present invention. Figures 1 to 10 The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the embodiments of the present invention include, but are not limited to, the embodiments described below. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] Example 1, Reference Figures 1 to 10 When piston 807 is driven by air pressure.

[0055] Taking an M6 socket head cap screw as an example, when the screw clamping part 2, in conjunction with the three-axis robot 1, moves the M6 ​​socket head cap screw to 3-5mm above the countersunk hole, the lead screw mechanism drives the electric screwdriver 4 to move until the fourth bit 504 is fully engaged with the socket head cap of the M6 ​​socket head cap screw. At this point, the air supply pipe 805 supplies air into the first space 8041, and the air enters the movable groove 806 from the first air hole 8081, pushing the piston 807 to move 4mm closer to the third bit 503. The piston 807 will drive the push rod 7 to move synchronously. After the push rod 7 moves 3.9mm, the hemisphere of the push rod 7 will contact the hemisphere of the top block 901 and push the top block 901 to move 0.1mm away from each other. At this time, the top block 901 contacts the socket head cap of the M6 ​​socket head cap screw and forms a 5N friction force, so that the fourth bit 504 can stably clamp the M6 ​​socket head cap screw. Driven by the lead screw mechanism, the fourth batch head 504 and the M6 ​​socket head cap screw advance 5cm in the countersunk hole. During this process, the axis of the M6 ​​socket head cap screw remains parallel to the axis of the countersunk hole. When the depth sensor detects that the M6 ​​socket head cap screw has made initial contact with the countersunk hole, the air supply pipe 805 stops supplying air to the first space 8041 and begins supplying air to the second space 8042. The gas enters the movable groove 806 through the second air hole 8082, pushing the piston 807 to move 4mm closer to the first batch head 501. At the same time, the push rod 7 moves synchronously with the piston 807. When the piston 807 contacts the protrusion 809, the piston 807 stops moving. At this time, the push rod 7 no longer contacts the push block 901. Under the attraction of the magnet, the push block 901 moves synchronously with the push rod 7. It stops moving when it encounters the limit protrusion 11, and the push block 901 is fully inserted into the second through hole 1002. As the push rod 7 moves, the control system activates the electric screwdriver 4, which drives the bit 5 to rotate. The M6 ​​socket head cap screw rotates synchronously with the bit 5. The lead screw mechanism advances in accordance with the pitch of the M6 ​​socket head cap screw, screwing the M6 ​​socket head cap screw into the countersunk hole. During the movement of the electric screwdriver 4, the bit 5 and the socket 802 rotate relative to each other, and the socket 802 moves synchronously and linearly with the bit 5, thus moving within the guide sleeve 801. When the depth detection sensor and torque detection sensor detect that the depth of the M6 ​​socket head cap screw and the friction force generated by the M6 ​​socket head cap screw reach 30mm and 6N·m respectively, it indicates that the M6 ​​socket head cap screw is installed in place. The electric screwdriver 4 stops rotating, and the three-axis robot 1 moves the bit 5 outside the countersunk hole to begin the next screw assembly cycle.

[0056] When the torque and depth sensors detect stripping and loosening of the M6 ​​socket head cap screw, the control system reverses the electric screwdriver 4, which, in conjunction with the lead screw mechanism, removes the M6 ​​socket head cap screw from the countersunk hole. Once the depth sensor detects that the M6 ​​socket head cap screw is completely disengaged from the screw hole, the air supply pipe 805 supplies air into the first space 8041. The air enters the movable groove 806 through the first air hole 8081, pushing the piston 807 to move 4mm closer to the third bit 503. The piston 807 then moves the push rod 7 synchronously. After the push rod 7 moves 3.9mm, its hemisphere contacts the hemisphere of the top block 901, pushing the top block 901 to move 0.1mm further away. At this point, the top block 901 contacts the socket head cap hole of the M6 ​​socket head cap screw, allowing the fourth bit 504 to stably clamp the M6 ​​socket head cap screw. When the lead screw mechanism drives the bit 5 out of the countersunk hole, the bit 5 simultaneously moves the M6 ​​socket screw out of the countersunk hole.

[0057] Example 2: When piston 807 is driven by hydraulic pressure.

[0058] The working process of power unit 8 and stationary unit 9 under hydraulic drive is the same as that under pneumatic drive, and will not be elaborated further here. However, it is necessary to improve the sealing between through hole 1001 and push rod 7 to prevent hydraulic oil leakage. Simultaneously, piston 807 needs to be replaced with a material with a density greater than hydraulic oil to prevent the buoyancy of piston 807 caused by hydraulic oil from affecting power unit 8 and stationary unit 9. Compared to pneumatic drive, hydraulic drive offers more stable transmission. The reduced friction between push block 901 and through hole 1002 increases the response speed of stationary unit 9 and extends the service life of push block 901. Furthermore, piston 807 is self-lubricating, extending its service life and reducing maintenance costs and time. However, since existing automatic screw assembly mechanisms are generally equipped with pneumatic systems for conveying and clamping screws, pneumatic drive does not require an additional pump body, only a valve body and pipelines. Hydraulic drive, on the other hand, requires a new hydraulic system, resulting in higher costs. The choice can be made based on the actual situation.

[0059] Although various embodiments of the present invention have been listed and described, it will be understood by those skilled in the art that many changes, modifications, substitutions and alterations can be made to the state and components of these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An automatic screw assembly mechanism, comprising: A three-axis robot has a screw clamping part fixedly installed on one of its movable sliders. The screw clamping part is equipped with a clamping mouth. A linear drive device is fixedly installed on the movable slider. An electric screwdriver is fixedly installed on the linear drive device. The electric screwdriver is equipped with a bit, which is located directly above the clamping mouth. The feature is that the bit is a combined bit, with a guide hole inside the bit, a push rod slidably installed in the guide hole, and a power unit installed on the bit for driving the push rod to move up and down. The power unit can move linearly and synchronously with the bit, and the power unit will not hinder the rotation of the bit. A fixing unit for stabilizing and fixing the screw is installed at the bottom of the bit, and when the push rod is subjected to the reaction force of the fixing unit to the point that it can no longer move downward, the fixing unit will lock the screw in place. It also includes a guide cylinder fixedly mounted on a movable slider, with the guide cylinder coaxial with the bit. A guide groove is provided on the side wall of the guide cylinder, and a sleeve is slidably mounted on the guide groove. The sleeve is rotatably mounted on the bit. A positioning element is installed on the bit to make the sleeve move linearly with the bit. A first space and a second space are respectively provided on the inner side wall of the sleeve. Both the first space and the second space are connected to air supply pipes. A movable groove is provided at the end of the guide hole near the electric screwdriver. A piston is slidably mounted in the movable groove. One side of the piston is fixedly connected to a push rod. A through hole is provided at the end of the movable groove away from the electric screwdriver, which fits tightly with the push rod. A first air hole and a second air hole are respectively provided on the bit, corresponding to the first space and the second space. Both the first air hole and the second air hole are connected to the movable groove. The first air hole and the second air hole are located on both sides of the piston. The first air hole and the second air hole are staggered along the bit axis. A protrusion is provided in the movable groove to prevent the piston from blocking the first air hole. The guide hole has a threaded groove at one end near the movable groove, and the threaded groove is located below the through hole. The push rod has a thread that mates with the threaded groove, and the lead angle of the thread is greater than ten degrees. The fixing unit includes two through holes symmetrically opened on the end of the bit away from the electric screwdriver. Each through hole is connected to the guide hole. A top block is slidably installed in each through hole. The end of the top block near the guide hole is hemispherical. The end of the top rod near the top block is hemispherical. A reset unit for automatically retracting the top block into the through hole is installed inside the bit. The second through hole is inclined downwards, and the angle between the second through hole and the horizontal plane is thirty degrees. The end face of the top block away from the hemisphere is parallel to the outer wall of the second through hole of the bit. The reset unit includes a hemispherical part of the push rod made of magnetic material, a hemispherical part of each top block made of a magnetically attractable material, and the push rod is always in contact with the top block. The cross-sectional shape of the second through hole is a non-rotational body, the cross-sectional shape of the non-spherical part of the top block is a non-rotational body that matches the second through hole, and the connection between the second through hole and the guide hole is a circular hole with a diameter equal to that of the hemispherical part of the top block. The end of the top block away from the top rod is provided with an elastic material to increase friction. When the top rod moves down to the limit position, the elastic material is squeezed and deformed, increasing the contact area with the screw. The top block and the second through hole are in a transition fit, and when the top rod moves upward, the space between the top blocks forms a negative pressure that pulls the top blocks to move closer to each other.

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