Device for tightening fine-thread flexible workpiece and tightening method thereof

Abstract

The invention relates to a device for tightening a fine-thread flexible workpiece and a tightening method thereof. The device for tightening the fine-thread flexible workpiece comprises a shape correction guide mechanism, a horizontal floating mechanism, a supporting mechanism and a screwing-in mechanism, and the shape correction guide mechanism is used for shape correction of the outer surface of the cross section of the fine-thread flexible workpiece to be tightened; the horizontal floating mechanism is used for installing an internal thread workpiece to be tightened; the supporting mechanism is fixed to one side of the shape correcting guide mechanism and provided with a lifting air cylinder, an upper limiting sensor and a lower limiting sensor. The screwing-in mechanism is arranged on the supporting mechanism, is driven by a lifting air cylinder to move up and down and comprises a motor, a planetary reducer, a torsion sensor and a universal floating joint mechanism, the universal floating joint mechanism is connected with the universal floating joint mechanism through a transmission shaft and a bearing which are coaxially connected, and an external thread workpiece is hoisted below the universal floating joint mechanism. The device for tightening the fine-thread flexible workpiece is suitable for tightening thin-wall soft metal fine threads, and damage is avoided.

Description

Technical Field

[0001] The present invention relates to the field of mechanical technology. Specifically, it relates to a device for tightening thin-walled and fine-thread flexible workpieces, especially a device and its tightening method for tightening fine-thread thin-walled flexible workpieces made of low-hardness metal materials after internal assembly of the warhead shell and the wind cap. Background Art

[0002] The warhead of a single soldier weapon usually consists of a wind cap (external thread workpiece), a projectile body component (internal thread workpiece), a propellant charge, etc.; the wind cap and the projectile body component are connected by fine threads, and the materials used for both parts are mostly soft metal material 2A12 aluminum alloy. Both parts are thin-walled and have fine threads, and the mouth of the thin-walled cylindrical section of the projectile body component is prone to ellipse, which brings assembly difficulties to the thread docking of the two parts.

[0003] Currently, existing tightening devices generally consist of a tightening gun or a tightening motor, a product fixing component, and a screw or workpiece to be tightened, and generally perform automatic tightening on thick threads or standard thread parts with high material hardness. When the existing tightening devices tighten the fine threads of thin-walled soft metal materials, the following problems will occur: 1). When tightening the fine threads of large-diameter thin-walled soft metal materials, the inner thread mouth deforms after processing due to the thin wall and cannot be threaded; 2). After the threads are threaded, due to the soft material, chips are easily generated, and the chips are blocked during the tightening process, causing damage to the thread tips; 3). After being screwed in, the product is blocked by chips in the thread grooves against the thread tips, resulting in deformation and protrusion of the outer wall of the thread, causing poor product surface. Due to the above problems, the existing tools and equipment cannot complete the automatic tightening of the fine threads of thin-walled soft metal materials. The existing equipment cannot achieve the automatic thread docking of the above two parts. Currently, only skilled workers can manually dock the two threads, and there are safety hazards in the pyrotechnic operation.

[0004] In response to the country's major decision-making arrangements regarding work safety and the requirements of safe work, systematic planning and active promotion of the automation of dangerous processes to replace human work are urgently needed. It is necessary to solve the automatic docking technology of thin-walled fine threads to fundamentally eliminate potential accident hazards. Therefore, there is an urgent need to develop a tightening device that can adapt to the fine threads of thin-walled soft metal materials, improve the manufacturing accuracy, and avoid product damage. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that when the existing part thread tightening method tightens the fine threads of thin-walled soft materials, it cannot be screwed in. The existing tightening devices cannot meet the tightening requirements of the fine threads of thin-walled soft metal materials, resulting in problems such as inability to thread, damage to the thread tips, deformation and protrusion of the outer wall of the thread, generation of chips after being screwed in, and deformation of the outer wall at the thread.

[0006] To solve the above technical problems, according to one aspect of the present invention, there is provided a device for tightening a fine-thread flexible workpiece. The fine-thread flexible workpiece includes an internal-thread workpiece and an external-thread workpiece. The device for tightening the fine-thread flexible workpiece includes: a shape-correcting and guiding mechanism, which has a base with a cavity in the middle and a pair of X-direction linear sliding rails on the upper part. A shape-correcting front slide plate and a shape-correcting rear slide plate that can move relatively are arranged on the sliding rails. The shape-correcting front slide plate and the shape-correcting rear slide plate are respectively connected to a shape-correcting guiding cylinder through a shape-correcting guiding cylinder connecting rod. The shape-correcting front slide plate and the shape-correcting rear slide plate are pushed by the shape-correcting guiding cylinder to move towards or away from each other along the X direction of the linear sliding rail. Among them, semi-circular grooves are opened on the adjacent sides of the shape-correcting front slide plate and the shape-correcting rear slide plate, and the inner diameter of the circular hole formed by the two semi-circular grooves is larger than the outer diameter of the cross-section of the fine-thread flexible workpiece to be tightened; a horizontal floating mechanism, which is arranged in the shape-correcting and guiding mechanism and is used for installing the internal-thread workpiece to be tightened. The horizontal floating mechanism includes a floor in contact with the base, and a fixed plate, a lateral floating plate, and an internal-thread workpiece clamping block arranged in sequence from bottom to top. The internal-thread workpiece clamping block includes an internal-thread workpiece front clamping block corresponding to the shape-correcting front slide plate and an internal-thread workpiece rear clamping block corresponding to the shape-correcting rear slide plate. Among them, a Z-direction lateral linear guide rail is arranged on the fixed plate to slidably connect the lateral floating plate, and an X-direction longitudinal linear guide rail is arranged on the lateral floating plate to respectively slidably connect the internal-thread workpiece front clamping block and the internal-thread workpiece rear clamping block. Among them, fixing holes are arranged on the fixed plate, the lateral floating plate, and the internal-thread workpiece clamping block. After the horizontal floating mechanism clamps the internal-thread workpiece, the internal-thread workpiece is fixed by a horizontal floating switch shaft connected to a horizontal floating switch cylinder passing through the fixing holes; a support mechanism, which is fixed on one side of the shape-correcting and guiding mechanism and extends upward in the Y direction. A lifting cylinder, an upper limit inductor, and a lower limit inductor are arranged on the support mechanism; a screwing-in mechanism, which is arranged on the support mechanism and is driven by the lifting cylinder to move up and down along the Y direction, includes an induction sheet, and also includes a motor, a planetary reducer, a torque sensor, and a universal floating joint mechanism arranged in sequence from top to bottom in the axial direction above the internal-thread workpiece. Among them, the universal floating joint mechanism is connected to the universal floating joint mechanism through a coaxial transmission shaft and a bearing. The external-thread workpiece is hoisted below the universal floating joint mechanism.

[0007] According to an embodiment of the present invention, the universal floating joint mechanism may include: a cylindrical external-thread workpiece connecting head, an external-thread workpiece connecting pin penetrating and connecting the external-thread workpiece and the lower end of the external-thread workpiece connecting head, a universal transmission block, a first universal transmission pin, and two second universal transmission pins. Among them, the universal transmission block is circular, the first universal transmission pin penetrates and slidably connects the universal transmission block and the lower end of the transmission shaft in the Z direction, and the two second universal transmission pins penetrate and slidably connect the external-thread workpiece connecting head and the universal transmission block on both sides of the transmission shaft in the Y direction, so as to realize the universal transmission when the external-thread workpieces are at the same height.

[0008] According to an embodiment of the present invention, the horizontal floating switch shaft may have multiple segments with unequal outer diameters along the axial direction. Among them, the segment with a larger outer diameter is the positioning segment, which is matched with the inner diameter of the fixing hole, and the segment with a smaller outer diameter is the clearance segment. When the horizontal floating switch cylinder pushes the horizontal floating switch shaft upward through the horizontal floating switch cylinder connector, the horizontal floating switch shaft is tightly matched with the fixing hole, so that the front clamping block of the internal thread workpiece, the transverse floating plate and the fixing plate are relatively fixed in position. When the horizontal floating switch cylinder pulls the horizontal floating switch shaft downward through the horizontal floating switch cylinder connector, there is a clearance between the horizontal floating switch shaft and the fixing hole, so that the front clamping block of the internal thread workpiece can freely float longitudinally and the transverse floating plate can freely float transversely.

[0009] According to an embodiment of the present invention, the shape correction guiding mechanism may further include: shape correction guiding blocks. There are two shape correction guiding blocks, which are respectively arranged on the semi-circular grooves of the front shape correction slide plate and the rear shape correction slide plate. The shape correction guiding blocks have arcs concentric with the semi-circular grooves of the front shape correction slide plate and the rear shape correction slide plate, and the inner diameter of the upper end of the shape correction guiding blocks is larger than the inner diameter of the lower end to facilitate the introduction of the external thread workpiece.

[0010] According to an embodiment of the present invention, the shape correction guiding mechanism may further include: shape correction guiding limit blocks. There are two shape correction guiding limit blocks, which are arranged on both sides of the opening between the front shape correction slide plate and the rear shape correction slide plate to prevent the front shape correction slide plate and the rear shape correction slide plate from being overly clamped and avoid deforming the thin-thread flexible workpiece to be tightened.

[0011] According to an embodiment of the present invention, the inner diameter of the hole between the transverse floating plate and the fixing plate for accommodating the internal thread workpiece may be greater than 1.2 times the outer diameter of the internal thread workpiece to ensure that there is no interference between the internal thread workpiece and the transverse floating plate and the fixing plate when the internal thread workpiece floats.

[0012] According to an embodiment of the present invention, when the screwing mechanism moves up and down in the Y direction, when the sensing piece triggers the upper limit sensor, the lifting cylinder stops controlling the screwing mechanism to move up further. When the sensing piece triggers the lower limit sensor, the lifting cylinder stops controlling the screwing mechanism to move down further.

[0013] According to an embodiment of the present invention, the device for tightening the thin-thread flexible workpiece may further include: an electro-hydraulic proportional valve, which is used to provide the required air pressure for the lifting cylinder, so that the entire external thread workpiece and the universal floating interface mechanism receive an upward thrust from the cylinder to control the slow descent of the external thread workpiece or the tightening in the zero-pressure state.

[0014] According to an embodiment of the present invention, the device for tightening the thin-thread flexible workpiece may further include: a PLC intelligent control unit, which is used to control the electro-hydraulic proportional valve to provide the required air pressure for the lifting cylinder.

[0015] On the other hand, according to the present invention, there is provided a method for tightening using the above-mentioned device for tightening a thin-thread flexible workpiece, including the following steps:

[0016] In the initialization state, the push-pull rod of the lifting cylinder is retracted, and the induction sheet just triggers the upper limit sensor; the connecting rod of the correction guide cylinder is retracted, so that the rear clamping block of the internal thread workpiece and the front clamping block of the internal thread workpiece are in the open state;

[0017] Material clamping: load the external thread workpiece into the external thread workpiece connection head hole, and then connect it through the external thread workpiece connection pin; clamp the internal thread workpiece through the internal thread workpiece rear clamping block and the internal thread workpiece front clamping block, and connect the internal thread workpiece rear clamping block and the internal thread workpiece front clamping block through screws;

[0018] Positioning of internal thread workpiece: After the internal thread workpiece is clamped, the horizontal floating switch cylinder push rod is extended to push the horizontal floating switch axis upward, and the fixed plate, the horizontal floating plate and the clamping block before clamping the external thread workpiece are positioned;

[0019] Start the device, and adjust the electric proportional valve to supply the air pressure to the lifting cylinder according to the set air pressure, so that the gravity of the entire external thread workpiece clamping device is greater than the upward thrust of the cylinder, so that the entire tightening unit will slowly descend to contact the internal thread workpiece, and at this time the induction sheet will trigger the lower limit sensor;

[0020] Internal thread shaping and external thread guiding. When the lower limit sensor is triggered, the two shaping and guiding cylinders are activated to push the shaping rear slide plate and the shaping front slide plate to the middle to clamp them, so as to shape the internal thread workpiece and guide the external thread workpiece.

[0021] After the internal thread workpiece is fixed at the docking interface and the external thread workpiece is guided, the electric proportional valve automatically adjusts the air pressure of the upward movement of the lifting cylinder, so that the downward gravity of the entire screwing mechanism minus the upward pulling force of the cylinder is equal to the weight of the external thread workpiece itself, thus ensuring that the downward pressure of the first turn is equal to the weight of the external thread workpiece;

[0022] Start the motor and tighten it one turn in the opposite direction of the screw thread and stop, so that the external thread workpiece is completely fitted with the internal thread workpiece under its own gravity; after tightening it one turn in the opposite direction, the motor starts to tighten it two turns in the forward tightening direction and then stops;

[0023] After turning it clockwise two turns, start two sizing guiding cylinders to return to their positions, pulling the sizing rear slide plate and the sizing front slide plate to move to both sides. At the same time, start the horizontal floating switch cylinder to pull the connecting head of the horizontal floating switch cylinder, pulling the horizontal floating switch shaft downward, so that the clearance sections on the upward axis of the horizontal floating switch shaft respectively correspond to the fixing holes of the front clamping block of the internal thread workpiece and the transverse floating plate, keeping a clearance between the horizontal floating switch shaft and the front clamping block of the internal thread workpiece and the transverse floating plate, allowing the front clamping block of the internal thread workpiece to float freely longitudinally and the transverse floating plate to float freely transversely; at the same time, the electro-hydraulic proportional valve adjusts the air pressure so that the upward pulling force of the cylinder is equal to the total weight of the screwing-in mechanism plus the external thread workpiece. At this time, the entire tightening mechanism can be almost in a zero-gravity state, making the downward pressure of the external thread workpiece on the internal thread workpiece zero;

[0024] Start the motor again for tightening work. During the tightening process, the tightening force is monitored in real time through a torque sensor until the set number of tightening turns is reached;

[0025] Remove the tightened workpiece to complete the tightening work.

[0026] Compared with the prior art, the technical solution provided by the embodiment of the present invention can at least achieve the following beneficial effects:

[0027] According to the device for tightening thin-thread flexible workpieces of the present invention, the workpiece to be screwed is externally rounded by a sizing guiding mechanism at the screwing port, and at the same time, the screwed-in thread is straightened to address the problem that the internal and external threads cannot be screwed into the first turn due to the thin wall deformation of the workpiece.

[0028] The present invention relaxes the workpiece after sizing the screwing-in port of the internal thread workpiece after screwing in one turn, making the horizontal floating mechanism for fixing the internal thread workpiece in a horizontally free state. At the same time, the screwed-in external thread workpiece is in a universal floating state, reducing the error of the parallelism between the threads machined on the workpiece and the clamping surface of the workpiece and the assembly cumulative tolerance of the tightened clamped workpiece.

[0029] The present invention controls the screwing-in pressure of the thread in stages. The screwing-in pressure for the first turn is 0.1 - 0.3 times the weight of the external thread workpiece as the screwing-in pressure. Starting from the second turn, it is screwed in with a zero-pressure floating state. In this way, during the thread screwing-in process, the friction force during the thread screwing-in process will not be increased due to too large or too small screwing-in pressure, thus causing heat generation and debris. The tightening process uses real-time monitoring of the tightening torque to stop the screwing-in work in time when the torque during the tightening process is abnormal compared with the normal data, without causing product damage.

[0030] According to the device for tightening thin-thread flexible workpieces of the present invention, it can achieve the tightening of soft materials, such as 2A12 aluminum material, thin-walled thin internal and external threads, and does not damage the threads during the tightening process, and can set the screwing-in force and the number of screwing-in turns.

[0031] The present invention provides a new tightening device. The technical solution adopted by this device is that the inner and outer threads are screwed against each other. During the first turn of screwing, the outer wall of the internal thread is shaped, and the external thread is guided and aligned before screwing. At the same time, the screwing pressure is controlled in stages, and the external thread workpiece has universal floating; starting from the second turn, the external thread is screwed in a zero-pressure floating state, and the internal thread workpiece floats horizontally freely. This can avoid the problems of debris generation and deformation of the outer wall at the thread after the external thread workpiece is screwed in, improve the machining accuracy and product yield, and improve the production efficiency.

[0032] The tightening device of the present invention is composed of an intelligent screwing-in mechanism for thin external thread workpieces, a fixing mechanism for thin internal thread workpieces, a thin thread shaping mechanism, and a PLC intelligent control unit; the thin external thread workpiece and the tightening head are connected by three round pins, and the thin internal thread workpiece is clamped by two workpieces similar in shape to the workpiece with screws. The tightening is driven by a servo motor, and at the same time, it is monitored in real time by a torque sensor to effectively control the tightening process. Brief Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only relate to some embodiments of the present invention and do not limit the present invention.

[0034] Figure 1 It is a schematic diagram of a device for tightening a thin thread flexible workpiece according to an embodiment of the present invention;

[0035] Figure 2 It is a schematic diagram of a universal floating joint mechanism according to an embodiment of the present invention;

[0036] Figure 3 It is an exploded view of the screwing-in mechanism according to an embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of the screwing-in mechanism, the shaping and guiding mechanism, and the horizontal floating mechanism according to an embodiment of the present invention;

[0038] Figure 5 It is a cross-sectional view of a device for tightening a thin thread flexible workpiece according to an embodiment of the present invention;

[0039] Figure 6 It is an exploded view of the horizontal floating mechanism according to an embodiment of the present invention;

[0040] Figure 7 It is a schematic diagram of an electro-hydraulic proportional valve according to an embodiment of the present invention;

[0041] Figure 8a and 8b respectively show the clearance fit and fixed fit states of the horizontal floating switch shaft and the fixed hole according to an embodiment of the present invention. Detailed implementation manners

[0042] For the purposes of making the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0043] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present invention pertains. The terms "first", "second" and similar terms used in the specification and claims of this patent application of the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, the terms such as "a" or "one" do not denote a quantity limitation, but mean that there is at least one.

[0044] Figure 1 is a schematic diagram of a device for tightening a flexible workpiece with fine threads according to an embodiment of the present invention; Figure 2 is a schematic diagram of a universal floating joint mechanism according to an embodiment of the present invention; Figure 3 is an exploded view of a screwing-in mechanism according to an embodiment of the present invention; Figure 4 is a schematic diagram of a screwing-in mechanism, a shape-correcting guiding mechanism and a horizontal floating mechanism according to an embodiment of the present invention; Figure 5 is a sectional view of a device for tightening a flexible workpiece with fine threads according to an embodiment of the present invention; Figure 6 is an exploded view of a horizontal floating mechanism according to an embodiment of the present invention.

[0045] As Figures 1 to 6 shown, for a device for tightening a flexible workpiece with fine threads, the flexible workpiece with fine threads includes an internal-thread workpiece and an external-thread workpiece. Among them, the device for tightening a flexible workpiece with fine threads includes: a shape-correcting guiding mechanism 8, a horizontal floating mechanism 9, a supporting mechanism and a screwing-in mechanism.

[0046] The shape-correcting guiding mechanism 8 has a base with a cavity formed in the middle and a pair of X-direction linear sliding rails 86 provided at the upper part. A shape-correcting front sliding plate 85 and a shape-correcting rear sliding plate 84 that can run relatively are arranged on the sliding rails. The shape-correcting front sliding plate 85 and the shape-correcting rear sliding plate 84 are respectively connected to a shape-correcting guiding cylinder 81 through a shape-correcting guiding cylinder connecting rod 82. The shape-correcting front sliding plate 85 and the shape-correcting rear sliding plate 84 are pushed by the shape-correcting guiding cylinder 81 to move towards or away from each other along the X direction of the linear sliding rail 86. Among them, semi-circular grooves are formed on the adjacent sides of the shape-correcting front sliding plate 85 and the shape-correcting rear sliding plate 84, and the inner diameter of the circular hole formed by the two semi-circular grooves is larger than the outer diameter of the cross-section of the thin-thread flexible workpiece to be tightened.

[0047] The horizontal floating mechanism 9 is arranged in the shape-correcting guiding mechanism 8 and is used for installing the internal-thread workpiece to be tightened. The horizontal floating mechanism 9 includes a floor in contact with the base, and a fixing plate 96, a transverse floating plate 94, and an internal-thread workpiece clamping block arranged in sequence from bottom to top. The internal-thread workpiece clamping block includes an internal-thread workpiece front clamping block 92 corresponding to the shape-correcting front sliding plate 85 and an internal-thread workpiece rear clamping block 91 corresponding to the shape-correcting rear sliding plate 84. Among them, a Z-direction transverse linear guide rail 95 is arranged on the fixing plate 96 to slidably connect the transverse floating plate 94, and an X-direction longitudinal linear guide rail 93 is arranged on the transverse floating plate 94 to slidably connect the internal-thread workpiece front clamping block 92 and the internal-thread workpiece rear clamping block 91 respectively. Among them, fixing holes are arranged on the fixing plate 96, the transverse floating plate 94, and the internal-thread workpiece clamping block. After the horizontal floating mechanism 9 clamps the internal-thread workpiece, the internal-thread workpiece is fixed by a horizontal floating switch shaft 97 connected to a horizontal floating switch cylinder 99 passing through the fixing holes.

[0048] The support mechanism is fixed on one side of the shape-correcting guiding mechanism 8 and extends upward in the Y direction. A lifting cylinder 5, an upper limit inductor 6, and a lower limit inductor 7 are arranged on the support mechanism.

[0049] The screwing-in mechanism is arranged on the support mechanism and is driven by the lifting cylinder 5 to move up and down along the Y direction. It includes an induction sheet 10, and also includes a motor 1, a planetary reducer 2, a torque sensor 3, and a universal floating joint mechanism 4 arranged in sequence from top to bottom in the axial direction above the internal-thread workpiece. Among them, the universal floating joint mechanism 4 is connected to the universal floating joint mechanism 4 through a coaxial transmission shaft 42 and a bearing 41, and an external-thread workpiece is hoisted below the universal floating joint mechanism 4.

[0050] For the device for tightening a thin-thread flexible workpiece according to the present invention, the workpiece to be screwed is externally round by the shape-correcting guiding mechanism 8 at the screwing port, and at the same time, the screwed-in thread is corrected to cope with the problem that the internal and external threads cannot be screwed into the first circle due to the deformation of the thin wall of the workpiece.

[0051] The device for tightening fine-thread flexible workpieces according to the present invention can achieve the tightening of soft materials, such as 2A12 aluminum material, with thin-walled fine internal and external threads, and does not damage the threads during the tightening process, and realizes the setting of the screwing-in force and the number of screwing-in turns.

[0052] As Figure 2 shown, the universal floating joint mechanism 4 includes: a cylindrical external thread workpiece connector 43, an external thread workpiece connecting pin 44 that penetrates and connects the external thread workpiece and the lower end of the external thread workpiece connector 43, a universal transmission block 46, a first universal transmission pin 45, and two second universal transmission pins 47. Among them, the universal transmission block 46 is annular, the first universal transmission pin 45 penetrates and slidably connects the universal transmission block 46 and the lower end of the transmission shaft 42 in the Z direction, and the two second universal transmission pins 47 penetrate and slidably connect the external thread workpiece connector 43 and the universal transmission block 46 on both sides of the transmission shaft 42 in the Y direction, so as to realize the universal transmission when the external thread workpieces are at the same height.

[0053] Figure 8a and 8b respectively show the clearance fit and fixed fit states of the horizontal floating switch shaft and the fixed hole according to the embodiments of the present invention.

[0054] As Figure 8a and 8b shown, the horizontal floating switch shaft 97 has multiple segments with unequal outer diameters along the axial direction. Among them, the larger outer diameter segment is the positioning segment, which is matched with the inner diameter of the fixed hole, and the smaller outer diameter segment is the clearance segment.

[0055] Among them, when the horizontal floating switch cylinder 99 pushes the horizontal floating switch shaft 97 upward through the horizontal floating switch cylinder connector 98, the horizontal floating switch shaft 97 is tightly fitted with the fixed hole, so that the inner thread workpiece front clamping block 92, the transverse floating plate 94 and the fixed plate 96 are relatively fixed in position; when the horizontal floating switch cylinder 99 pulls the horizontal floating switch shaft 97 downward through the horizontal floating switch cylinder connector 98, the horizontal floating switch shaft 97 maintains a clearance with the fixed hole, so that the inner thread workpiece front clamping block 92 can freely float longitudinally and the transverse floating plate 94 can freely float transversely.

[0056] According to one or some embodiments of the present invention, the shape correction guiding mechanism 8 further includes: shape correction guiding blocks 83. There are two shape correction guiding blocks 83, which are respectively arranged on the semi-circular grooves of the shape correction front slide plate 85 and the shape correction rear slide plate 84. The shape correction guiding blocks 83 have arcs concentric with the semi-circular grooves of the shape correction front slide plate 85 and the shape correction rear slide plate 84, and the inner diameter of the upper end of the shape correction guiding blocks 83 is larger than the inner diameter of the lower end, so as to facilitate the introduction of the external thread workpieces.

[0057] According to one or some embodiments of the present invention, the shape-correcting guiding mechanism 8 further includes: two shape-correcting guiding limit blocks 87, which are arranged on both sides of the opening between the shape-correcting front slide plate 85 and the shape-correcting rear slide plate 84, and are used to prevent the shape-correcting front slide plate 85 and the shape-correcting rear slide plate 84 from being overly clamped, so as to avoid deforming the thin-thread flexible workpiece with tightening.

[0058] According to one or some embodiments of the present invention, the inner diameter of the hole for accommodating the inner-thread workpiece between the lateral floating plate 94 and the fixed plate 96 is greater than 1.2 times the outer diameter of the inner-thread workpiece, so as to ensure that there is no interference between the inner-thread workpiece and the lateral floating plate 94 and the fixed plate 96 when the inner-thread workpiece floats.

[0059] According to one or some embodiments of the present invention, when the screwing-in mechanism moves up and down in the Y direction, when the sensing piece 10 triggers the upper limit sensor 6, the lifting cylinder 5 stops controlling the screwing-in mechanism from moving up further, and when the sensing piece 10 triggers the lower limit sensor 7, the lifting cylinder 5 stops controlling the screwing-in mechanism from moving down further.

[0060] Figure 7 It is a schematic diagram of an electro-hydraulic proportional valve showing an embodiment of the present invention.

[0061] As Figure 7 shown, the device for tightening the thin-thread flexible workpiece further includes: an electro-hydraulic proportional valve, which is used to provide the required air pressure for the lifting cylinder 5, so that the entire external-thread workpiece and the universal floating interface mechanism receive an upward thrust from the cylinder, so as to control the slow descent or tightening in the zero-pressure state of the external-thread workpiece.

[0062] According to one or some embodiments of the present invention, the device for tightening the thin-thread flexible workpiece further includes: a PLC intelligent control unit, which is used to control the electro-hydraulic proportional valve to provide the required air pressure for the lifting cylinder 5.

[0063] The tightening device of the present invention is composed of an intelligent screwing-in mechanism for thin external-thread workpieces, a fixing mechanism for thin internal-thread workpieces, a thin-thread shape-correcting mechanism and a PLC intelligent control unit; the thin external-thread workpiece and the tightening head are connected by three round pins, and the thin internal-thread workpiece is clamped by two workpieces similar to the workpiece shape with screws. The tightening is driven by the servo motor 1, and at the same time, it is monitored in real time by the torque sensor 3 to effectively control the tightening process.

[0064] According to another aspect of the present invention, there is provided a method for tightening using the above-mentioned device for tightening the thin-thread flexible workpiece, including the following steps:

[0065] Initialization state, the push rod of the lifting cylinder 5 retracts, and the sensing piece 10 just triggers the upper limit sensor 6; the connecting rod of the shape-correcting guiding cylinder 82 retracts, so that the inner-thread workpiece rear clamping block 91 and the inner-thread workpiece front clamping block 92 are in the open state;

[0066] Workpiece clamping: Insert the external thread workpiece into the hole of the external thread workpiece connector 43, and then connect it through the external thread workpiece connecting pin 44; Clamp the internal thread workpiece with the rear clamping block 91 and the front clamping block 92 of the internal thread workpiece. The rear clamping block 91 and the front clamping block 92 of the internal thread workpiece are connected by screws.

[0067] Internal thread workpiece positioning: After the internal thread workpiece is clamped, the push rod of the horizontal floating switch cylinder 99 extends to push the horizontal floating switch shaft 97 upward, positioning the fixed plate 96, the lateral floating plate 94, and the front clamping block for clamping the external thread workpiece.

[0068] Starting device: Adjust the pneumatic pressure supplied to the lifting cylinder 5 through the electro-pneumatic proportional valve according to the set air pressure, so that the self-weight of the entire external thread workpiece clamping device is greater than the upward thrust of the cylinder. In this way, the entire tightening unit will slowly descend to contact the internal thread workpiece. At this time, the induction piece 10 triggers the lower limit inductor 7.

[0069] Internal thread calibration and external thread guiding: When the lower limit inductor 7 is triggered, two calibration and guiding cylinders 81 are started to push the rear calibration slide plate 84 and the front calibration slide plate 85 towards the middle for clamping, calibrating the internal thread workpiece and guiding the external thread workpiece.

[0070] After fixing the interface of the internal thread workpiece and guiding the external thread workpiece, the electro-pneumatic proportional valve automatically adjusts the intake air pressure for the upward movement of the lifting cylinder, so that the downward gravity of the entire screwing mechanism minus the upward pulling force of the cylinder is equal to the weight of the external thread workpiece itself. In this way, it is ensured that the downward pressure in the first turn of screwing is equal to the weight of the external thread workpiece.

[0071] Start the motor 1 to turn one circle in the direction opposite to the thread and then stop, so that the external thread workpiece completely fits with the internal thread workpiece under its own gravity; After turning one circle in the reverse direction, the motor 1 starts to turn two circles in the forward tightening direction and then stops.

[0072] After turning two circles in the forward direction, start the two calibration and guiding cylinders 81 to retract and pull the rear calibration slide plate 84 and the front calibration slide plate 85 to move to both sides. At the same time, start the horizontal floating switch cylinder 99 to pull the horizontal floating switch cylinder connector 98 to pull the horizontal floating switch shaft 97 downward, so that the clearance sections of the horizontal floating switch shaft 97 in the axial direction correspond to the fixing holes of the front clamping block 92 of the internal thread workpiece and the lateral floating plate 94 respectively, keeping a clearance between the horizontal floating switch shaft 97 and the front clamping block 92 of the internal thread workpiece and the lateral floating plate 94, allowing the front clamping block 92 of the internal thread workpiece to float freely longitudinally and the lateral floating plate 94 to float freely laterally; At the same time, the electro-pneumatic proportional valve adjusts the air pressure so that the upward pulling force of the cylinder is equal to the total weight of the screwing mechanism plus the external thread workpiece. At this time, the entire tightening mechanism is almost in a zero-gravity state, making the downward pressure of the external thread workpiece on the internal thread workpiece zero.

[0073] Restart the motor 1 to perform the tightening operation. During the tightening process, the tightening force is monitored in real time through the torque sensor 3 until the set number of tightening turns is reached;

[0074] Remove the tightened workpiece to complete the tightening operation.

[0075] In the present invention, after screwing in one turn, the workpiece at the entrance of the internal thread is relaxed to make the horizontal floating mechanism 9 for fixing the internal thread workpiece in a horizontally free state. At the same time, the screwed external thread workpiece is in a universal floating state, reducing the error of the parallelism between the threads machined on the workpiece and the clamping surface of the workpiece and the assembly cumulative tolerance of the tightened and clamped workpiece.

[0076] The present invention controls the screwing pressure of the threads in stages. The screwing pressure for the first turn is 0.1 - 0.3 times the weight of the external thread workpiece. Starting from the second turn, it is screwed in with a zero-pressure floating state. In this way, during the thread screwing process, excessive or too small screwing pressure will not increase the friction force during the thread screwing process, thus causing heat generation and debris. The tightening torque is monitored in real time during the screwing process to stop the screwing operation in time when the torque ratio during the tightening process is abnormal compared with the normal data, without causing damage to the product.

[0077] The present invention provides a new tightening device. The technical solution adopted by this device is that when the internal and external threads are screwed against each other, the outer wall of the internal thread is shaped during the first turn, and the external thread is guided correctly before screwing in. At the same time, the screwing pressure is controlled in stages and the external thread workpiece has universal floating; starting from the second turn, the external thread is screwed in with a zero-pressure floating state, and the internal thread workpiece floats horizontally freely. Thus, the problems of debris generation and deformation of the outer wall at the thread after the external thread workpiece is screwed in are avoided, the machining accuracy and the product yield are improved, and the production efficiency is increased.

[0078] The above is only an exemplary embodiment of the present invention, rather than being used to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A device for tightening a fine thread flexible workpiece, the fine thread flexible workpiece comprising an internal thread workpiece and an external thread workpiece, wherein: The device for tightening fine thread flexible workpieces includes: A shape correction guide mechanism, wherein the shape correction guide mechanism has a base, a cavity is arranged in the middle, and a pair of X-direction linear slide rails are arranged on the upper part, and a front shape correction slide plate and a rear shape correction slide plate that can move relatively are arranged on the slide rails, and the front shape correction slide plate and the rear shape correction slide plate are connected to the shape correction guide cylinder through the shape correction guide cylinder connecting rod respectively, and the front shape correction slide plate and the rear shape correction slide plate are pushed by the shape correction guide cylinder to move toward or away from each other along the linear slide rail in the X direction, wherein the adjacent sides of the front shape correction slide plate and the rear shape correction slide plate are provided with semicircular grooves, and the inner diameter of the circular hole formed by the two semicircular grooves is larger than the outer diameter of the cross section of the fine thread flexible workpiece to be tightened; A horizontal floating mechanism is arranged in the shape correction guide mechanism and is used for installing an internal thread workpiece to be tightened. The horizontal floating mechanism includes a floor in contact with a base, and a fixed plate, a transverse floating plate, and an internal thread workpiece clamping block arranged in sequence from bottom to top. The internal thread workpiece clamping block includes a front clamping block of the internal thread workpiece corresponding to the front shape correction slide plate and a rear clamping block of the internal thread workpiece corresponding to the rear shape correction slide plate, wherein a transverse linear guide in the Z direction is arranged on the fixed plate to slidably connect the transverse floating plate, and a longitudinal linear guide in the X direction is arranged on the transverse floating plate to slidably connect the front clamping block of the internal thread workpiece and the rear clamping block of the internal thread workpiece, respectively, wherein fixing holes are arranged on the fixed plate, the transverse floating plate, and the internal thread workpiece clamping block, and after the horizontal floating mechanism clamps the internal thread workpiece, the horizontal floating switch shaft connected to the horizontal floating switch cylinder passes through the fixing hole to fix the internal thread workpiece; A support mechanism is fixed on one side of the shape correction guide mechanism and extends upward in the Y direction. A lifting cylinder, an upper limit sensor, and a lower limit sensor are arranged on the support mechanism. The screwing mechanism is arranged on the supporting mechanism and is driven by the lifting cylinder to move up and down along the Y direction. It includes a sensing sheet and also includes a motor, a planetary reducer, a torque sensor, and a universal floating joint mechanism arranged in sequence from top to bottom in the axial direction above the internal thread workpiece, wherein the universal floating joint mechanism is connected to the universal floating joint mechanism through a coaxially connected transmission shaft and a bearing, and the external thread workpiece is hoisted below the universal floating joint mechanism.

2. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: The universal floating joint mechanism includes: a cylindrical externally threaded workpiece connecting head, an externally threaded workpiece connecting pin penetrating and connecting the externally threaded workpiece and the lower end of the externally threaded workpiece connecting head, a universal transmission block, a first universal transmission pin and two second universal transmission pins, wherein the universal transmission block is annular, the first universal transmission pin penetrates through the Z direction and slidably connects the universal transmission block and the lower end of the transmission shaft, and the two second universal transmission pins penetrate through the Y direction and slidably connect the externally threaded workpiece connecting head and the universal transmission block on both sides of the transmission shaft, thereby realizing universal transmission when the externally threaded workpieces are at the same height.

3. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: The horizontal floating switch shaft has multiple sections with different outer diameters along the axial direction, wherein the section with a larger outer diameter is a positioning section that matches the inner diameter of the fixing hole, and the section with a smaller outer diameter is a gap section. Among them, when the horizontal floating switch cylinder pushes the horizontal floating switch shaft upward through the horizontal floating switch cylinder connecting head, the horizontal floating switch shaft and the fixed hole fit tightly, so that the front clamping block of the internal thread workpiece, the transverse floating plate and the fixed plate are relatively fixed in position; when the horizontal floating switch cylinder pulls the horizontal floating switch shaft downward through the horizontal floating switch cylinder connecting head, the horizontal floating switch shaft and the fixed hole maintain a gap, so that the front clamping block of the internal thread workpiece can float freely in the longitudinal direction and the transverse floating plate can float freely in the transverse direction.

4. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: The shaping guide mechanism also includes: shaping guide blocks, two of which are respectively arranged on the semicircular grooves of the front shaping slide plate and the rear shaping slide plate, the shaping guide blocks have arcs concentric with the semicircular grooves of the front shaping slide plate and the rear shaping slide plate, and the inner diameter of the upper end of the shaping guide block is larger than the inner diameter of the lower end, so as to facilitate the introduction of external threaded workpieces.

5. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: The shape correction guide mechanism also includes: shape correction guide limit blocks, which are two in number and are arranged on both sides of the opening between the front shape correction slide and the rear shape correction slide to prevent the front shape correction slide and the rear shape correction slide from being over-clamped, thereby avoiding deformation of flexible workpieces with tightened fine threads.

6. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: The inner diameter of the hole between the transverse floating plate and the fixed plate for accommodating the internal thread workpiece is greater than 1.2 times the outer diameter of the internal thread workpiece to ensure that the internal thread workpiece does not interfere with the transverse floating plate and the fixed plate when floating.

7. The device for tightening a fine thread flexible workpiece according to claim 1, wherein: When the screwing mechanism Y moves up and down, when the induction plate triggers the upper limit sensor, the lifting cylinder stops controlling the screwing mechanism to continue to move up, and when the induction plate triggers the lower limit sensor, the lifting cylinder stops controlling the screwing mechanism to continue to move down.

8. The device for tightening a fine thread flexible workpiece according to claim 1, further comprising: The electrical proportional valve is used to provide the required air pressure for the lifting cylinder, so that the entire external thread workpiece and the universal floating interface mechanism are pushed upward by the cylinder to control the external thread workpiece to slowly descend or tighten it in a zero pressure state.

9. The device for tightening a fine thread flexible workpiece according to claim 1, further comprising: The PLC intelligent control unit is used to control the electrical proportional valve to provide the air pressure required by the lifting cylinder.

10. A method for tightening a fine-threaded flexible workpiece using the device for tightening a fine-threaded flexible workpiece according to any one of claims 1 to 9, comprising the following steps: In the initialization state, the push-pull rod of the lifting cylinder is retracted, and the induction sheet just triggers the upper limit sensor; the connecting rod of the correction guide cylinder is retracted, so that the rear clamping block of the internal thread workpiece and the front clamping block of the internal thread workpiece are in the open state; Material clamping: load the external thread workpiece into the external thread workpiece connection head hole, and then connect it through the external thread workpiece connection pin; clamp the internal thread workpiece through the internal thread workpiece rear clamping block and the internal thread workpiece front clamping block, and connect the internal thread workpiece rear clamping block and the internal thread workpiece front clamping block through screws; Positioning of internal thread workpiece: After the internal thread workpiece is clamped, the horizontal floating switch cylinder push rod is extended to push the horizontal floating switch axis upward, and the fixed plate, the horizontal floating plate and the clamping block before clamping the external thread workpiece are positioned; Start the device, and adjust the electric proportional valve to supply the air pressure to the lifting cylinder according to the set air pressure, so that the gravity of the entire external thread workpiece clamping device is greater than the upward thrust of the cylinder, so that the entire tightening unit will slowly descend to contact the internal thread workpiece, and at this time the induction sheet will trigger the lower limit sensor; Internal thread shaping and external thread guiding. When the lower limit sensor is triggered, the two shaping and guiding cylinders are activated to push the shaping rear slide plate and the shaping front slide plate to the middle to clamp them, so as to shape the internal thread workpiece and guide the external thread workpiece. After the internal thread workpiece is fixed at the docking interface and the external thread workpiece is guided, the electric proportional valve automatically adjusts the air pressure of the upward movement of the lifting cylinder, so that the downward gravity of the entire screwing mechanism minus the upward pulling force of the cylinder is equal to the weight of the external thread workpiece itself, thus ensuring that the downward pressure of the first turn is equal to the weight of the external thread workpiece; Start the motor and tighten it one turn in the opposite direction of the screw thread and stop, so that the external thread workpiece is completely fitted with the internal thread workpiece under its own gravity; after tightening it one turn in the opposite direction, the motor starts to tighten it two turns in the forward tightening direction and then stops; After two turns of forward tightening, start the two correction guide cylinders to return and pull the correction rear slide plate and the correction front slide plate to move to both sides. At the same time, start the horizontal floating switch cylinder to pull the horizontal floating switch cylinder connector to pull the horizontal floating switch shaft downward, so that the gap section on the axial direction of the horizontal floating switch shaft corresponds to the fixing holes of the front clamping block of the internal thread workpiece and the horizontal floating plate respectively, so that a gap is maintained between the horizontal floating switch shaft and the front clamping block of the internal thread workpiece and the horizontal floating plate, so that the front clamping block of the internal thread workpiece can float freely in the longitudinal direction and the horizontal floating plate can float freely in the horizontal direction; at the same time, the electric proportional valve adjusts the air pressure so that the upward pulling force of the cylinder is equal to the total weight of the screwing mechanism plus the external thread workpiece. At this time, the entire tightening mechanism can be almost in a zero gravity state, so that the downward pressure of the external thread workpiece on the internal thread workpiece is 0; The motor is started again to tighten the parts. During the tightening process, the tightening force is monitored in real time by the torque sensor until the set number of tightening turns is reached. Remove the tightened workpiece to complete the tightening work.

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