Three-jaw flexible floating chuck and small workpiece cylindrical grinding machine

Abstract

The utility model relates to a three-jaw flexible floating chuck and a small workpiece cylindrical grinding machine. An oil cylinder of the three-jaw flexible floating chuck is a multi-rod hollow oil cylinder, piston rods are distributed at equal intervals, sliding rails are connected with the front ends of the piston rods corresponding to the sliding rails and are in axial sliding connection with the profiling templates corresponding to the sliding rails, inclined grooves serving as sliding plate guide grooves are formed in the sliding rails, and L-shaped guide grooves are formed in the inner walls, located on the outer sides of the sliding plate guide grooves, of the profiling templates. The outer side face of each sliding plate is provided with a profiling guide structure extending into the corresponding L-shaped guide groove, the profiling guide structures on the outer side faces of the sliding plates are in guide fit with the corresponding L-shaped guide grooves of the sliding plates respectively, and the clamping seats are located on the radial inner sides of the mounting plates on the corresponding sliding plates respectively and connected with the mounting plates. Live centers and the floating chucks are arranged on a headstock and a tailstock of the small workpiece cylindrical grinding machine, and the live centers penetrate through the hollow parts of the floating chucks. The small-sized workpiece cylindrical grinding operation requirement of the numerical control grinding machine can be better met.

Description

Technical Field

[0001] The utility model relates to a three-jaw flexible floating chuck and a small workpiece external cylindrical grinder adopting such a floating chuck, belonging to the field of mechanical technology. Background Art

[0002] The headstock and tailstock of existing grinding machines mostly use chucks for workpiece clamping. By clamping the workpiece, it is connected to the workbench, and the workpiece is rotated by the power of the machine tool for machining operations such as cutting and grinding. There are various forms of existing chucks. They can be classified into two-jaw chucks, three-jaw chucks, four-jaw chucks, six-jaw chucks, and special chucks according to the number of chuck jaws; they can be classified into manual chucks, pneumatic chucks, hydraulic chucks, electric chucks, and mechanical chucks according to the power used; and they can be classified into hollow chucks and solid chucks according to the structure. For example, Chinese Patent Document CN111673617A discloses a floating-jaw chuck for a grinding machine, which includes a first chuck, a second chuck, a chute, a first slider, a chuck jaw, a rotating rod, a spring, a first movable block, a first turntable, a fixed shaft, a rotating block, an end face gear, a gear ring, a second turntable, a second movable block, a second slider, a fixed block, a connecting rod, a fixed rod, an extension shaft, a screw, a nut, a sleeve shaft, and a limiting rod. Through the design of the rotating rod, when clamping the workpiece, the rotating rod first contacts the workpiece. When continuing to clamp, the rotation of the rotating rod pushes the workpiece to move axially, improving the stability of workpiece clamping through the floating of the workpiece and avoiding the problem of workpiece offset during machining; through the design of the second chuck, it is convenient to support the inner wall of the tubular workpiece, solving the problem of workpiece deformation caused by excessive force when clamping the tubular workpiece and also avoiding the problem of workpiece movement caused by insufficient clamping force. Chinese Patent Document CN115723044A discloses a floating chuck for an external grinding machine, which uses a cylinder to drive a pawl and drive a ratchet to rotate. A one-way needle roller bearing restricts the reverse rotation of the floating disk, and a positioning shaft is fixed on the floating disk; three chuck jaws are driven to rotate bidirectionally along their respective positioning shafts by the ratchet and an energy storage device. The jaw part of the chuck jaw is an eccentric arc; there is a gap between the inner hole of the floating disk and both sides and the mounting seat. The three chuck jaws are driven to rotate in the reverse direction through a split mechanism, and the built-in energy storage device drives the three chuck jaws to rotate in the forward direction. The jaw part of the chuck jaw is an eccentric arc, realizing the expansion and contraction of the chuck jaw opening. The floating disk controls the effective contact between the jaw part of each chuck jaw and the rotating shaft, thereby realizing the automatic clamping and loosening of the rotating shaft. Through a pneumatically driven floating chuck, the automatic clamping and loosening during the grinding process of the rotating shaft are realized. During operation, the driving mechanism is separated from the chuck, and at the same time, the occupied length of the fixture is short, providing a necessary condition for realizing the automation of rotating shaft grinding. Chinese Patent Document CN107225445A discloses a high-precision hydraulic chuck for a CNC precision external grinding machine, which includes a chuck body, a spring, a spring bolt, a clamping sliding sleeve, a chuck jaw, an oil cylinder top pin, a piston, and an oil cylinder cover. A reciprocating piston is provided on one side inside the chuck body. An oil cylinder cover is provided outside the piston. Multiple reciprocating clamping sliding sleeves are respectively movably connected to the inside of the piston through oil cylinder top pins. A stack spring and a stack spring bolt for fixing the stack spring are installed inside the clamping sliding sleeve. Its design is unique, with a small volume, large clamping force, convenient adjustment, good repeatability and reproducibility, fast action response, no indentation on the workpiece by a group of asymmetric arc chuck jaws, and a long service life.Chinese Patent Document CN113878495A discloses a floating jaw chuck for a grinding machine, which includes a base. An installation groove is formed on the base. The installation groove is of a convex structure. A jaw is arranged in the installation groove, and the jaws can be adjusted independently. A universal coupling is movably installed between the side surfaces of adjacent jaws. By providing a plurality of jaws that can be adjusted independently and a centering mechanism in the jaws, the position and state of the jaws can be independently adjusted according to the shape and eccentricity of the workpiece surface, so as to better directly clamp the workpiece, making the workpiece not deviate from the machining center without the need to install other auxiliary mechanisms. By providing a telescopic universal coupling, it will not limit the independent adjustment of the position of each jaw, and at the same time, when adjusting the angle of one eccentric cam, the angles of the other eccentric cams will also change synchronously, which is convenient for loading and unloading the workpiece. These prior arts each have their own characteristics and are respectively applicable to their respective suitable occasions, but there are still certain limitations. For example, when used for small-sized (e.g., shaft diameters at both ends < φ20) workpieces such as motor rotors, it should adapt to the operation mode of alternating driving of the headstock and tailstock of a CNC cylindrical grinding machine. The chuck must not affect the center runout of the workpiece when driving the workpiece. The chuck needs to withdraw from the loading and unloading area to avoid interference during robot loading and unloading. The chuck needs to withdraw from the grinding area to avoid interference when grinding both ends of the workpiece with a grinding wheel. And the chuck jaws (or other forms of clamping parts) should have sufficient stroke to clamp small-diameter workpieces. The chuck jaws must moderately pull the workpiece towards the center point when clamping the workpiece to adapt to the characteristics of poor shaft rigidity of small-sized workpieces. Since none of the above prior arts can well meet these requirements, it is necessary to further develop a floating chuck and related devices that can better be applicable to small-sized workpieces. Summary of the Invention

[0003] The object of the present invention is to provide a three-jaw flexible floating chuck and an external cylindrical grinding machine for small-sized workpieces to better meet the requirements of external cylindrical grinding operations of small-sized workpieces on a CNC grinding machine.

[0004] The technical solution of the utility model is: a three-jaw flexible floating chuck, including an oil cylinder, a clamping seat, a clamping jaw, a profiling template, a slide rail and a slide plate. The oil cylinder is a multi-rod hollow oil cylinder, provided with a hollow oil cylinder body (rotary cylinder body, referred to as the cylinder body for short) and a piston conforming to the inner cavity of the oil cylinder body (the inner cavity of the cylinder body). The piston is annular, installed with a plurality of piston rods distributed at equal intervals (equal angular intervals). Each piston rod extends axially, passes through the oil cylinder end cover at the front end of the oil cylinder body, and its rear end is installed on the piston, and its front end is respectively connected to its corresponding slide rail. The profiling templates are fixedly installed in front of the oil cylinder body, and the number is multiple. Each slide rail is axially slidably connected to its corresponding profiling template (connected in a movable connection manner allowing relative axial sliding between the two). An inclined groove serving as a guide groove for the slide plate is provided on the slide rail. The slide plate guide groove is arranged on the circumferential end face (the surface at one circumferential end) of the slide rail. Each slide plate is slidably matched with its corresponding slide plate guide groove (connected in a movable connection manner allowing relative sliding between the two). An L-shaped guide groove is provided on the inner wall of the profiling template outside the slide plate guide groove (the inner wall facing the notch of the slide plate guide groove). Profiling guide structures respectively extending into their corresponding L-shaped guide grooves are provided on the outer side surfaces (the side surfaces on the notch side of the slide plate guide groove) of each slide plate. The profiling guide structures on the outer side surfaces of each slide plate are respectively in guiding cooperation with the L-shaped guide grooves corresponding to each slide plate (a cooperation manner defining the relative movement trajectory / direction of the two). Installation plates are provided at the front ends of each slide plate. Each clamping seat is located radially inside the installation plate on its corresponding slide plate and is connected to the installation plate. Each clamping jaw is fixedly installed at the inner end of its corresponding clamping seat. The central axis (the central axis of the groove cavity, including the extension line) of the slide plate guide groove intersects the central axis (rotation axis) of the oil cylinder behind the slide plate axially. The L-shaped guide groove includes an axial section and a radial section. The extension direction of the axial section is axial (the direction parallel to the central axis of the oil cylinder). The radial section is connected to the front end of the axial section and extends radially inward, and its extension direction is slightly inclined relative to the radial direction (a small angle of inclination, for example, an inclination greater than 0° and not greater than 10°). The inner end (radial inner end) of the radial section is located axially behind the outer end (radial outer end).

[0005] Based on the clamping stability, reliability and the convenience and possibility of the layout of each component in practice, usually, the number of the piston rods can be 3, and when necessary, other numbers of piston rods can also be set.

[0006] Usually, the number of the piston rods, profiling templates, slide rails, slide plates, clamping seats and clamping jaws is the same and they correspond to each other one by one.

[0007] Preferably, the clamping jaw is an elastic clamping jaw.

[0008] Preferably, the connection of the clamping seat to the corresponding installation plate is a floating connection.

[0009] For example, the mounting plate is provided with a light hole (which can be called a floating connection hole) that penetrates both inside and outside (radially inside and outside). A pin for floating connection of the card seat passes through the corresponding floating connection hole, and its tail is threadedly connected to the outer end face (the outer end face in the radial direction) of the card seat. Its head is stuck outside (radially outside) the floating connection hole. An isolation sleeve is provided between the pin for floating connection of the card seat and the floating connection hole, and the inner and outer tube walls of the isolation sleeve are respectively in contact with (without leaving a gap) the pin for floating connection of the card seat and the floating connection hole.

[0010] Furthermore, the mounting plate is also provided with a screw hole (which can be called a floating connection screw hole) that penetrates both inside and outside (radially inside and outside). The outer end face of the card seat is provided with a T-shaped groove with a larger inner diameter and a smaller outer diameter. A spherical screw used for floating connection of the card seat is screwed (threadedly connected) to the corresponding floating connection screw hole, and its head is clamped in (located in) the T-shaped groove on the outer end face of the card seat and its inner end abuts against / fits with the bottom of the T-shaped groove.

[0011] Preferably, the profiling template adopts a rectangular cylindrical structure. The slide rail conforms to the inner cavity of the profiling template and is in the shape of a rectangular block. The main part of the slide plate conforms to the slide plate guiding groove (groove cavity) and is in the shape of a plate, and its cross-section is in any suitable shape such as a rectangle or a trapezoid. The inner wall of the profiling template located outside the slide plate guiding groove is flat (the main part is flat), adheres to the outside of the slide plate guiding groove, and together with the slide plate guiding groove forms a hole-shaped structure (which can be called a slide plate guiding hole) that guides and cooperates (or is called a sliding fit) with the slide plate (the main part of the slide plate).

[0012] Preferably, the profiling guiding structure on the outer side surface of the slide plate includes rollers for profiling guiding and pin shafts for profiling guiding. The outer diameters of the rollers for profiling guiding and the pin shafts for profiling guiding are both smaller than the width of the L-shaped guiding groove (including the axial section width and the radial section width of the L-shaped guiding groove).

[0013] Generally, the number of rollers for profiling guiding and pin shafts for profiling guiding can both be one. When necessary, multiple ones can also be used.

[0014] Furthermore, the rollers (rollers for profiling guiding) on the same outer side surface of the slide plate are located on the front side of the pin shaft (pin shaft for profiling guiding) in the axial direction and on the outer side of the pin shaft in the radial direction.

[0015] Furthermore, the outer diameter of the roller for profiling guiding is larger than the outer diameter of the pin shaft for profiling guiding.

[0016] The connection method between the front end of the piston rod and the corresponding slide rail can be a fixed connection or any other suitable connection method.

[0017] Preferably, the connection method between the front end of the piston rod and the corresponding slide rail is a floating connection.

[0018] For example, a T-shaped groove with a larger inner diameter and a smaller outer diameter is provided on the rear end face of the slide rail, a spherical crown-shaped diameter-expanded portion is provided at the front end of the piston rod, the spherical crown-shaped diameter-expanded portion is clamped in the T-shaped groove on the corresponding rear end face of the slide rail, and its front end abuts / fits against the bottom of the T-shaped groove.

[0019] Further, the two oil circuit interfaces of the oil cylinder (the rod chamber interface and the non-rod chamber interface, which can be respectively referred to as the first interface and the second interface of the oil cylinder) are respectively connected to the two oil circuit interfaces of the hydraulic control system through their respective rotary joints (correspondingly, they can be respectively referred to as the first interface and the second interface of the hydraulic control system), thereby forming a supply and return oil circuit for the hydraulic oil of the oil cylinder (the specific form of the circuit depends on the setting of the hydraulic control system).

[0020] Further, the rotary joint is rotatably installed on the outside of the cylinder block.

[0021] Further, a one-way valve with a self-locking function is provided in the hydraulic control system.

[0022] The small workpiece external cylindrical grinder is mainly used for external cylindrical grinding of small workpieces and other suitable occasions, and is provided with a grinding machine (or grinding machine body) and a manipulator for loading and unloading the grinding machine. The grinding machine is provided with a headstock and a tailstock. Floating chucks and center points are provided on both the headstock and the tailstock. The floating chuck adopts any one of the three-jaw flexible floating chucks disclosed in the present invention. The center point is a live center point, which passes through the hollow of the floating chuck. The rotary cylinder body of the floating chuck and the end of the live center point are respectively fixedly installed on the main shafts (the headstock main shaft or the tailstock main shaft) of their respective headstocks or tailstocks.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1) The floating chuck adopts a rotary oil cylinder with a hollow structure, which can be directly installed on the rotary main shafts of the headstock and the tailstock, and can cooperate with the center point to form a workpiece clamping mechanism to jointly clamp the workpiece, adapting to the operation mode of alternately driving the workpiece by the headstock and the tailstock;

[0025] 2) Using the same piston to drive multiple (for example, three) piston rods to move synchronously, the consistency of the actions of each jaw is achieved, and there is no need to set up a synchronous transmission / speed regulation mechanism;

[0026] 3) The jaws are made of polyurethane or POM materials, realizing flexible clamping and not scratching the workpiece;

[0027] 4) Guiding the movement of the jaws through a profiling guide rail / L-shaped guide groove, the movement trajectory is reasonable, convenient for operation, and after the jaws extend, they move and clamp the workpiece at an inclination of 2°, pulling the workpiece towards the corresponding center point direction, which can better adapt to the characteristics of poor shaft rigidity of small workpieces;

[0028] 5) The axial positioning self-locking is achieved through a hydraulic control check valve;

[0029] 6) It is suitable for fully automatic operation. The workpiece can be inserted into the chuck without manual axial movement, and the center of the workpiece can be calibrated without manually adjusting each jaw separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the front view schematic diagram of the floating chuck of the present utility model (X-X cross-sectional view, clamping position);

[0031] Figure 2 is the top view schematic diagram of the floating chuck of the present utility model (Y-Y cross-sectional view, loosening position);

[0032] Figure 3 is the side view schematic diagram of the floating chuck of the present utility model (view in the Z direction);

[0033] Figure 4 is the structural schematic diagram of the quick adjustment mechanism of the floating chuck related to the present utility model;

[0034] Figure 5 is the kinematic diagram of the floating chuck of the present utility model;

[0035] Figure 6 is the schematic diagram of the principle of the hydraulic control system of the floating chuck of the present utility model;

[0036] Figure 7 is the schematic diagram of the use state of the floating chuck of the present utility model cooperating with the manipulator for loading and unloading;

[0037] Figure 8 is the structural schematic diagram of the hollow swing cylinder related to the present utility model, where the left figure shows the front view of the piston and the piston rod, and the right figure shows the side view of the distribution of the swing cylinder body and the piston rod;

[0038] Figure 9 is the structural schematic diagram of the flexible clamping mechanism related to the present utility model;

[0039] Figure 10 is the structural schematic diagram of the floating connection mechanism related to the present utility model, where the left figure is the front view of the relevant part, and the right figure is the side view;

[0040] Figure 11 is the layout diagram of the grinding machine related to the present utility model;

[0041] Figure 12 is the schematic diagram of the structure and working principle of the L-shaped guide groove related to the present utility model. DETAILED DESCRIPTION OF THE INVENTION

[0042] I. Composition of the floating chuck

[0043] See Figures 1 - 4 , this floating chuck includes the following parts: part A (hollow oil cylinder and rotary joint), part B (three-piston-rod hollow piston, or three-rod hollow piston), part C (floating connection mechanism, or floating connection bracket), part D (flexible clamping jaw mechanism), and part F (copying guide rail mechanism). Among them, part A (hollow oil cylinder and rotary joint) includes: oil cylinder end cover A1, sealing ring A2, oil cylinder body A3, sealing ring A4, rotary joint A5, bearing A6, bearing spacer A7, rotary joint A8, sealing ring A9, sealing ring A10, screw A11, screw A12, and screw A13; part B (three-piston-rod hollow piston) includes: piston B1, piston rods B2 (3 pieces), snap ring B3, sealing ring B4, and sealing ring B5; part C (floating connection mechanism) includes: spherical screw C1, nut C2, screw C3, and rubber spacer C4; part D (flexible clamping jaw mechanism) includes: flexible jaw D1 and clamping seat D2; part F (copying guide rail mechanism) includes: copying template F1, slide rail F2, slide plate F3, roller F4, and pin shaft F5.

[0044] In addition, when the floating chuck is used in the headstock or tailstock of the cylindrical grinder involved in the present utility model, it also involves: small workpiece E1 (for example, motor rotor), center E2, spindle (for example, headstock spindle, tailstock spindle) E3, and grinding wheel E4.

[0045] Figure 1 and Figure 2 respectively show the clamping state and the loosening state of the floating chuck. In the loosening state, after the oil cylinder drives the piston rods B2 and the flexible jaws D1 to retract, they move away from the workpiece E1 and the grinding wheel E4, leaving a movement space for the end face grinding of the workpiece and the loading and unloading of the manipulator, avoiding interference and obstruction.

[0046] The cylinder body (or oil cylinder body) A3 of the rotary oil cylinder has an annular (cross-section is annular) hollow structure, and the center is a hole (or hollow, usually a cylindrical hole, adapted to the shape of the center, allowing the live center to pass through to perform corresponding functions) for passing through the live center. The oil cylinder end cover A1 and the sealing rings at various places can be configured according to the conventional oil cylinder design method, and the area range / interface between the oil cylinder body (main part) and the end cover can be divided on the entire cylinder body according to the convenience of processing and assembly. The shape of the piston B1 is adapted to the shape of the annular inner cavity of the oil cylinder. The three piston rods are evenly distributed on the same circumference, pass through the respective through holes on the oil cylinder end cover A1, and their right ends (located inside the cylinder) are fixedly installed on the piston by means of threaded connection (a fastening nut can be set), and the left ends (or the front left ends, located outside the cylinder) are connected to the slide rail F2.

[0047] The slide rail F2 is block-shaped and can be in the shape of a square column (rectangular column) whose central axis (or axis, including extension line) is parallel to the central axis of the cylinder body A3. The central axis preferably overlaps with the central axis of the corresponding piston rod B2 (is located on the same straight line). The connection between the piston rod end and the slide rail can be a fixed connection, preferably a floating connection. When a floating connection is adopted, the front part of the piston rod can be provided with a spherical crown-shaped expansion part similar to the head of a spherical screw, and the spherical crown-shaped expansion part is clamped in a T-slot with a larger inner part and a smaller outer part provided on the rear end surface of the slide rail. The top end of the spherical crown-shaped expansion part abuts / fits with the bottom of the T-slot, and a gap is left around the top end and the inner wall of the T-slot to allow the slide rail to have a slight swing and slide relative to the piston rod.

[0048] A slide guide groove for guiding the slide F3 is provided on one circumferential side of the slide rail F2. The slide guide groove is an oblique groove (a straight groove extending obliquely). If necessary, slide guide grooves can also be provided on both circumferential sides of the slide rail F2. The central axis of the slide guide groove (the central axis of the groove cavity, or the central axis of the area on the slide that slides with the slide guide groove) preferably intersects with the central axis of the oil cylinder / oil cylinder body at the axial (axial) rear side of the slide guide groove. A portion (rear portion) of the slide F3 is located in the slide guide groove (during normal operation, the slide F3 always remains partially located in the slide guide groove), and slides with the slide guide groove (or the hole-shaped structure formed by the slide guide groove and the inner wall of the corresponding part of the profiling template F1, which can be called a slide guide hole), and can reciprocate in the axial direction of the slide guide groove under the limitation of the slide guide groove, that is, move obliquely forward and backward. Therefore, when the slide F3 moves forward relative to the slide rail F2 under the limitation of the slide guide groove, it must also move outward (outward in the radial direction) relative to the slide rail F2 at the same time.

[0049] The main body of the slide plate F3 may be generally in the shape of a plate, and its cross section may be rectangular.

[0050] The profiling template F1 adopts a rectangular cylindrical structure or other structures that can limit the axial movement of the slide rail F2 (slidingly connected axially to the slide rail F2) and have an L-shaped guiding groove on the side of the slide rail F2. The rear end of the profiling template F1 is fixedly connected (for example, by welding, bolt fastening / screw connection, etc.) to the cylinder end cover A1 (the front end of the cylinder block). The slide rail F1 is located inside the profiling template (during normal operation, at least a part of the slide rail F1 is located inside the cylindrical structure of the profiling template). Among the two circumferential inner walls (inner walls parallel to the axial and radial directions) of the profiling template F1, at least one inner wall is provided with an L-shaped guiding groove. The L-shaped guiding groove includes an axial section and a radial section. The extending direction of the axial section is parallel to the central axis of the cylinder (along the axial direction of the cylinder), and the radial section is connected to the front end of the axial section and extends radially inward. Its extending direction has a slight inclination with respect to the radial direction (for example, it can be 2°). The inner end is at the rear (the inner end is on the axial rear side of the outer end). On the side of the slide plate opposite to the L-shaped guiding groove, outwardly protruding rollers F4 and pin shafts F5 are provided. The rollers F4 and pin shafts F5 extend into the corresponding L-shaped guiding grooves. The outer diameters of the rollers F4 and pin shafts F5 located in the L-shaped guiding grooves are both smaller than the width of the L-shaped guiding groove (including the width of the axial section and the width of the radial section, and the width of the axial section and the width of the radial section of the L-shaped guiding groove can be the same or different). The outer diameter of the roller F4 can be larger than the outer diameter of the pin shaft F5 or not larger than the outer diameter of the pin shaft F5. The central axes (or rotation axes) of the roller F4 and the pin shaft F5 are parallel to each other and are both perpendicular to the surface of the slide plate where the two (the roller F4 and the pin shaft F5) are located. Therefore, it should usually also be perpendicular to the bottom of the L-shaped guiding groove and perpendicular to the inner wall of the profiling template F1 where the L-shaped guiding groove is located.

[0051] According to actual needs, the roller F4 can be replaced by a pin shaft with the same outer diameter, and the pin shaft F5 can be replaced by a roller with the same outer diameter.

[0052] In the radial direction, the roller F4 is preferably located outside the pin shaft F5; in the axial direction, the roller F4 is preferably located in front of the pin shaft F5.

[0053] The front end of the slide plate F3 is provided with a mounting plate located outside the guiding groove (always located outside the guiding groove during operation). The spherical screw C1 is fixedly installed on the mounting plate with its head facing inward. For example, a screw hole penetrating in the inner and outer directions can be provided on the mounting plate, and the spherical screw is screwed (thread-connected) into the screw hole. And a nut C2 can be screwed onto the tail of the spherical screw, and the nut C2 is tightened so that it presses tightly against the outside of the mounting plate, thereby fixing the spherical screw to prevent it from loosening during operation.

[0054] On the outer end face (radial outer end face) of the clamping seat D2, there is a T-shaped groove with a larger inner diameter and a smaller outer diameter that mates (fits) with the spherical screw. The head of the spherical screw is clamped in (located in) this T-shaped groove, and the top of the spherical head of the screw abuts / coincides with the bottom of this T-shaped groove. There is a gap between the periphery of the top and the inner wall of this T-shaped groove to allow the clamping seat D2 to have a slight swing and sliding relative to the spherical screw.

[0055] The mounting plate is also provided with a floating connection hole that penetrates in the inner and outer directions. The pin C3 for floating connection passes through the floating connection hole, and the tail is threadedly connected to the outer end face of the clamping seat (a screw hole matching the pin C3 is provided on this end face). The head is stuck outside the floating connection hole. An isolation sleeve is provided (filled) between the pin C3 and the floating connection hole, and the isolation sleeve is in a certain compressed state. Thus, the floating connection between the mounting plate (slide plate F3) and the clamping seat D2 (and the flexible claw D1 fixedly installed at the inner end of the clamping seat) is realized through the isolation sleeve.

[0056] A flexible claw (or elastic claw) D1 with a certain elasticity can be fixedly installed (for example, embedded) at the inner end (radial inner end) of the clamping seat D2 according to any suitable prior art.

[0057] The fixed connection of each relevant part can be realized by welding and threaded connection (for example, the fastening connection of connectors such as screws, bolts, and nuts) according to actual needs. The matching method and matching clearance (when set) of each movable connection can be set according to actual needs. The connection and sealing of the oil circuit can be realized by setting a sealing ring, etc. A rabbet or stepped connection / fitting surface can be provided between the mutually connected parts according to actual needs.

[0058] II. Working Principle of the Floating Chuck

[0059] The cylinder block A3 of the oil cylinder is fixed to the spindle E3 of the headstock (or tailstock) or the rotary dial of the headstock (or tailstock) with 4 screws A12. Hydraulic oil is pumped into the rotary oil cylinder through the rotary joint A5 (pressure air can also be used to replace the hydraulic oil. In this case, the so-called oil cylinder can be regarded as / equivalently replaced by a cylinder). The piston B1 is pushed to move leftward, and the 3 piston rods B2 fixed on the piston B1 make an extending movement, pushing 3 groups of guide rail components (slide rail F2, slide plate F3, roller F4, pin shaft F5) to move. Among them, the slide rail F2 moves leftward together with the piston rod B2. The extending parts of the roller F4 and the pin shaft F5 are inserted into the L-shaped guide groove on the profiling template F1. Under the common limitation of the profiling template F1 and the slide rail F2, the slide rail F2 and the roller F4, pin shaft F5, and spherical screw C1 fixedly installed on the slide rail F2 make corresponding profiling movements. In the area corresponding to the axial straight section in the L-shaped guide groove, the clamping seat D2 is flexibly driven to move leftward through the rubber spacer sleeve C4 and the workpiece E1 is sleeved (at this time, the 3 groups of flexible claws D1 in the clamping seat D2 extend synchronously), and the extending action is completed.

[0060] As the piston B1 continuously moves to the left, the roller F4 or the pin shaft F5 on the slide plate F3 rolls or slides along the L-shaped guide groove on the profiling template F1, and then flexibly drives the clamping seat D2 and the three flexible jaws D1 at its inner end to perform an L-shaped movement through the rubber spacer sleeve C4. After the extending action is completed, under the limitation of the straight-line segment in the L-shaped guide groove (slightly inclined relative to the radial direction, for example, 2°), the three flexible jaws D1 clamp the workpiece E1 from three directions with a radial movement trajectory tilted backward by 2°, and apply a force pushing the workpiece E1 towards the center point E2, pushing the workpiece E1 towards the center point E2, and the clamping action is completed.

[0061] During the clamping process, connection floating is synchronously achieved, that is, the clamping seat D2 floats in multiple directions among the six rubber spacer sleeves C4, including the elastic deformation floating of the six rubber spacer sleeves C4 in the axial direction and the elastic deformation floating in the radial direction, and also includes the floating achieved by the sliding of the three spherical screws C1 on the three clamping seats D2.

[0062] In addition, since the material of the three flexible jaws D1 is polyurethane or POM, which has appropriate elasticity, during the process of clamping the workpiece E1, elastic deformation occurs to achieve flexible clamping.

[0063] During the process of the chuck clamping (clamping) the workpiece E1, the workpiece E1 has been centered by the two live center points E2. Through the above-mentioned floating connection and flexible clamping, the influence (over-positioning) of the floating chuck on the center of the workpiece E1 during the clamping process is avoided.

[0064] III. Layout Structure of the Floating Chuck

[0065] The three groups of piston rods B2, spherical screws C1, flexible jaws D1, and F4 slide plates are evenly distributed within a 360° circumferential range (or in the circumferential direction, or on the circumference). In addition, within the 360° circumferential range, there are also evenly distributed parts such as three rubber spacer sleeves C4.

[0066] Since the spherical screw C1 needs to be inserted into the T-shaped groove of the clamping seat D2 without obstruction during installation, occupying a certain amount of space. To avoid interference, the spherical screws C1, clamping seats D2, rubber spacer sleeves C4, etc. of each group are distributed at intervals of 120°, and there is also a certain distance or angular interval between the components of the same group according to actual needs. Similarly, to avoid interference, an angular interval of 15° is set between the oil circuit interfaces of the screw A12 and the rotary joint A8.

[0067] According to the standards of the cylindrical grinder type spectrum, it is also necessary to avoid interference with the grinding wheel, which restricts the radial space of the floating chuck. At the same time, in order to set the center E2, the shape of the chuck must be hollow. Since the length of the center E2 is limited (too long will reduce the stiffness of the support positioning), the axial space of the floating chuck is also restricted. In the limited space, it is necessary and effective to accommodate many mechanisms such as floating connection, flexible clamping, hollow oil cylinder, rotary joint, three-rod piston, profiling template, etc. with the above-mentioned staggered layout method.

[0068] IV. Quick adjustment mechanism of the floating chuck

[0069] See Figure 4 , the floating chuck is applied to the automatic production line. Therefore, it should be able to be quickly adjusted when changing workpieces to meet the functional requirements of the fixture for changing the clamping range. For example, the vulnerable parts - flexible jaws D1 can be quickly replaced by removing 3 spherical screws C1 and the chuck seat D2; the vulnerable parts - rubber sleeves C4 can be quickly replaced by removing 3 snap rings C5 and screws C3.

[0070] For the change of the diameter size of the workpiece E1, the part - chuck seat D2 (its height and shape are scaled accordingly) can be quickly replaced by removing 3 screws C3.

[0071] V. Movement mode of the floating chuck

[0072] See Figure 5 , the floating chuck has 3 groups of composite slider mechanisms, which can realize large axial stroke movement and small radial stroke movement (floating). The 3 groups of chuck seats D2 and jaws D1 can move and rotate in the 3 groups of floating connections of spherical screws C1 and rubber sleeves C4 to ensure the required floating function when clamping the workpiece E1.

[0073] VI. Hydraulic control system of the floating chuck

[0074] See Figure 6 , this hydraulic control system of the floating chuck includes: oil pump F1, pressure reducing valve F2, pressure gauge F3, electromagnetic directional valve F4, pilot-operated check valve F5 and oil cylinder F6.

[0075] The hydraulic control principle is: the extension and retraction actions of the floating chuck are realized by switching the electromagnetic directional valve F4, and the clamping force of the three-rod piston floating chuck is realized by adjusting the pressure reducing valve F2 (the pressure gauge F3 can be observed). During the grinding process, if the cylindrical grinder encounters sudden power failure or faults such as insufficient pressure caused by the damage of the oil pump F1, the pilot-operated check valve F5 will lock the oil cylinder F6 to stop moving and avoid potential safety hazards.

[0076] VII. Working mode of the floating chuck cooperating with the manipulator for loading and unloading

[0077] SeeFigure 7 Regarding the relevant parts of the floating chuck cooperating with the manipulator, they include: the headstock G1, the floating chuck G2, the tailstock G3, and the manipulator G4.

[0078] The working mode of the floating chuck cooperating with the manipulator for loading and unloading: With the continuous improvement of production efficiency in the modern machining industry, the demand for high-efficiency cylindrical grinding machines is increasing. It is required to cooperate with the manipulator for automatic loading and unloading on the fully automatic production line; at the same time, it is also required that a cylindrical grinding machine can grind the outer cylindrical parts at both ends of the workpiece after one clamping. Therefore, corresponding functional requirements for this floating chuck have emerged. Compared with the common technology, it is possible to cancel the installation of driving chucks at both ends of the workpiece E1, and directly drive the workpiece E1 after clamping both ends by the floating chuck G2 without scratching the clamping parts. When the manipulator G4 is loading and unloading, the floating chuck G2 is in the loosened position and does not interfere with the manipulator G4.

[0079] VIII. Structure and Related Features of the Floating Chuck

[0080] 1. Three-rod hollow piston (see Figure 8 )

[0081] 1) Compared with the common standard oil cylinder with only 1 piston and 1 piston rod, the oil cylinder of the present utility model is a piston with a hollow structure and provided with 3 piston rods (which can be called a three-rod hollow piston). Since it is impossible to ensure that each piston rod reaches the same speed and synchronization when driving 3 piston rods with 3 standard oil cylinders respectively, a synchronization mechanism and a speed regulation mechanism need to be set. However, by using one piston with three piston rods (other numbers of piston rods can also be set according to actual needs), the synchronization of the three piston rods is fundamentally ensured, and there is no need to set a synchronization mechanism and a speed regulation mechanism.

[0082] 2) Compared with the closed (solid) structure of the standard oil cylinder, the end covers A1 and the cylinder block A3 of the oil cylinder of the present utility model both adopt an annular structure, forming a hollow structure as a whole. The live center E2 can pass through the middle of the end cover A1 of the oil cylinder, ensuring the requirement of centering the live center E2 of the cylindrical grinding machine for the workpiece E1.

[0083] 3) From the perspective of processing technology, in order to ensure the smooth operation of the 3 piston rods B2, 3 through holes for assembling the 3 piston rods B2 can be machined on both the end cover A1 of the oil cylinder and the piston B1 at the same time to ensure the positional tolerance of the through holes relative to the center of the part.

[0084] 2. Flexible clamping mechanism (see Figure 9 )

[0085] 1) Three flexible jaws D1 clamp the workpiece E1 from three directions. The jaw material is polyurethane or POM, which is elastic and has a hardness (Shore 50 - 80 HA) lower than that of the workpiece (HRC 40 - 60), so it will not cause scratches. Since it involves the surface of the already ground workpiece, if metal hard jaws of a double V-block chuck or a three-cam chuck are used under the existing technology, sliding between the jaws and the workpiece during the clamping process is likely to produce scratches.

[0086] 2) The movement mode / track of the flexible jaw D1 is to perform radial contraction at an angle of 2° relative to the radial direction and press the workpiece towards the center point direction.

[0087] 3) The elastic deformation of the flexible jaw D1 is beneficial to clamping and protecting the workpiece surface. At the same time, it can also automatically adapt to the shape of the workpiece to avoid over-positioning. The jaw is made of elastic material. After clamping the workpiece, the local deformation of the contact part is a circular arc close to the workpiece, with a large contact area, making it easy to hold and clamp the workpiece. At the same time, the frictional force generated by the pressure makes it difficult for the jaw and the workpiece to slide relative to each other.

[0088] 4) The swing base of the three flexible jaws D1 is the clamping seat D2, which can float during the clamping process, enabling better self-adaptation to clamp the ground workpiece E1.

[0089] 5) Since the workpiece processed by the cylindrical grinder is centered by the two center points at its two ends, and the runout and dimensional tolerance of the outer circle surface have reached the processing requirements of the pre-grinding process (for example, 0.04 mm). After being clamped by the floating of the three-rod piston chuck, at the same time, the flexible jaws D1 made of polyurethane produce elastic deformation, enabling the three flexible jaws D1 to clamp the workpiece better. During the grinding process, sufficient clamping force is continuously maintained through hydraulic oil. The configured hydraulic control one-way valve can achieve hydraulic locking to prevent fixture failures when the machine tool suddenly loses power.

[0090] 3. Floating connection mechanism (see Figure 10 )

[0091] 1) Components involved: spherical screw C1, nut C2, screw C3, rubber spacer C4, snap ring C5, clamping seat D2 and flexible jaw D1.

[0092] 2) Clamping process: The slide plate F3 makes an L-shaped movement, and the flexible jaws D1 mounted on it continuously contract. When the flexible jaws D1 clamp the workpiece E1, floating is achieved through the elastic deformation of the rubber spacer C4, avoiding over-positioning.

[0093] 3) Dialing process: After clamping, the clamping seat D2 and the workpiece E1 are fixed as a whole. The three piston rods B2 dial the clamping seat D2 and the workpiece E1 through the respective rubber spacers C4; at the same time, with the elastic deformation of the rubber spacers C4, floating is achieved.

[0094] 4. Rotary joint

[0095] A rotary joint is adopted so that the oil pipe does not twist when the main shaft (such as the headstock main shaft or the tailstock main shaft) rotates. Based on the outer circle of the cylinder block A3 of the oil cylinder, the rotary joints A5 and A8 are supported by two bearings A6 to make a rotary motion, and both ends are sealed by two sealing rings A4.

[0096] 5. Related structures for preventing scratches and not affecting runout

[0097] 1) When the manipulator automatically loads and unloads the workpiece, the clamping seat D2 and the jaws D1 can quickly move away from the workpiece to facilitate the manipulator to load and unload the workpiece, avoiding interference and collision accidents. At the same time, when the manipulator leaves, the clamping action should be quickly completed, reducing the manual operation of loading and unloading the clamp, reducing the labor intensity, and improving the processing efficiency.

[0098] 2) When replacing the workpiece, the outer diameter changes. The clamping range of the jaws can be adjusted accordingly by bolts (from φ100 to φ150), quickly realizing the adjustment of the fixture and improving the processing efficiency.

[0099] 3) Three flexible jaws D1 clamp the workpiece, making it easy to adjust the jaws and not causing damage to the workpiece surface.

[0100] 4) Because the rubber spacer C4 has the ability of elastic deformation, it will not affect the runout of the workpiece during the dialing process (similar to a flexible coupling).

[0101] IX. Loading and clamping mechanism (or clamping mechanism) and grinding machine

[0102] See Figure 11 , the floating chuck of the present utility model can be combined with a live center to form a workpiece loading and clamping mechanism of the machine tool, which is used for the headstock and the tailstock of the grinding machine. Such a grinding machine can perform external circle grinding on both ends of the workpiece after clamping a small workpiece such as a motor rotor at one time.

[0103] Such a grinding machine includes: a headstock G1, a floating chuck G2, a tailstock G3, a grinding wheel head G4, a workbench G5, etc., and can complete the external circle grinding of both ends of the workpiece after clamping at one time, which is beneficial to realizing automated processing.

[0104] X. L-shaped guide groove of the profiling template and the movement track of the jaws limited thereby

[0105] See Figure 12 and Figure 5 , in order to meet the requirements of the external grinding machine for grinding both ends of small workpieces, it can simultaneously meet: 1) The center can be detached (for example, a hollow oil cylinder with a hole diameter of φ34 is adopted); 2) The release position can avoid the grinding wheel to avoid interference (for example, axially move 20 mm); 3) Since the outer diameter of the workpiece is small (for example, the shaft diameter is less than φ20 and the radial movement is 10 mm) and the rigidity is insufficient, the workpiece can be pressed against the center (tilted at an angle of 2°).

[0106] Limited by the narrow space, the utility model adopts an L-shaped guide groove and other guiding cooperation methods to achieve the motion trajectory control method related to the above-mentioned multiple functions.

[0107] When the slide rail F2 extends, the inclined groove (guide groove) on it guides the slide plate F3 to extend. At the same time, the roller F4 on the slide plate F3 rolls along the L-shaped guide groove on the profiling template F1, and drives the slide plate F3 to move synchronously in an L-shaped motion. In addition, in order to ensure smooth operation and avoid interference, the gap between the L-shaped guide groove and the roller F4 is enlarged. At the same time, in order to avoid inconsistent actions and waste the limited stroke of the oil cylinder during the conversion of clamping and loosening, a pin shaft F5 is added close to the L-shaped guide groove. When loosening, the pin shaft F5 replaces the movement of the roller F4 (the roller F4 disengages from the L-shaped guide groove and hangs in the air).

[0108] When the floating chuck of the utility model and the live center are used together as the headstock and tailstock of a small workpiece external grinder, it not only adapts to the operation mode of alternately driving small workpieces (for example, the shaft diameters at both ends < φ20), but also has the following functional characteristics:

[0109] 1) When the manipulator loads and unloads workpieces, the floating chuck automatically withdraws from the loading and unloading area to avoid interference;

[0110] 2) When the grinding wheel grinds both ends of the workpiece, the floating chuck withdraws from the grinding area to avoid interference;

[0111] 3) The floating chuck is hollow, which is convenient for replacing the center and avoids interference;

[0112] 4) The jaws have sufficient stroke and can effectively and reliably clamp workpieces with small shaft diameters;

[0113] 5) When the jaws clamp the workpiece, the workpiece is tightened towards the center, adapting to the characteristics of poor shaft rigidity of small workpieces;

[0114] 6) The jaws are made of materials with appropriate flexibility. In the case where the surface of the workpiece has been ground, the jaws will not scratch the surface of the workpiece;

[0115] 7) The jaws are floating and do not affect the center runout of the workpiece when driving the workpiece.

[0116] All directional indicators (such as left, right, etc.) in this specification are only used to explain the relative position relationship of each relevant component in a corresponding direction or the relative position relationship in multiple directions under a certain specific posture or implementation manner, and do not constitute a limitation on the actual use direction. If the specific posture changes, the directional indicator will also change accordingly. It can also be understood that at least partial exchange of the relative positions in some directions (for example, the circumferential direction) does not prevent the implementation of the technical solution.

[0117] All the preferred and optional technical means disclosed by the present utility model can be arbitrarily combined to form several different specific embodiments, unless otherwise specified or one preferred or optional technical means further limits another technical means.

Claims

1. Three-jaw flexible floating chuck, comprising an oil cylinder, a chuck base and a jaw, characterized in that It further includes a profiling template, a slide rail and a slide plate. The oil cylinder is a multi-rod hollow oil cylinder, which is provided with a hollow oil cylinder body and a piston conforming to the oil cylinder body. The piston is annular and is installed with a plurality of piston rods distributed at equal intervals or equal angular intervals. Each piston rod extends axially, passes through the oil cylinder end cover located at the front end of the oil cylinder body, and its rear end is installed on the piston. Its front end is respectively connected to its corresponding slide rail. The profiling templates are fixedly installed on the front of the oil cylinder body and are multiple in number. Each slide rail is axially slidably connected to its corresponding profiling template. The slide rail is provided with an inclined groove serving as a slide plate guiding groove. An L-shaped guiding groove is provided on the inner wall of the profiling template outside the slide plate guiding groove. The outer side surface of each slide plate is provided with a profiling guiding structure respectively extending into its corresponding L-shaped guiding groove. The front end of each slide plate is provided with a mounting plate. Each clamping seat is located radially inside the mounting plate on its corresponding slide plate and is connected to the mounting plate. Each clamping jaw is fixedly installed at the inner end of its corresponding clamping seat. The central axis of the slide plate guiding groove intersects with the central axis of the oil cylinder at the rear of the slide plate axially. The L-shaped guiding groove includes an axial section and a radial section. The extending direction of the axial section is axial. The radial section is connected to the front end of the axial section and extends radially inward. Its extending direction is slightly inclined relative to the radial direction. The inner end of the radial section is located at the rear of the outer end axially.

2. The three-jaw flexible floating chuck according to claim 1, characterized in that The clamping jaw is an elastic clamping jaw.

3. The three-jaw flexible floating chuck according to claim 1, characterized in that The connection of the clamping seat on the corresponding mounting plate is a floating connection.

4. The three-jaw flexible floating chuck according to claim 3, wherein The mounting plate is provided with a floating connection hole penetrating through from inside to outside. The pin for the floating connection of the clamping seat passes through the corresponding floating connection hole. Its tail is threadedly connected to the outer end surface of the clamping seat. Its head is stuck outside the floating connection hole. An isolation sleeve is provided between the pin for the floating connection of the clamping seat and the floating connection hole. The inner and outer side walls of the isolation sleeve are respectively in contact with the pin for the floating connection of the clamping seat and the floating connection hole.

5. The three-jaw flexible floating chuck according to claim 4, wherein The mounting plate is further provided with a floating connection screw hole penetrating through from inside to outside. The outer end surface of the clamping seat is provided with a T-shaped groove with a large inner diameter and a small outer diameter. The spherical screw for the floating connection of the clamping seat is screwed on the corresponding floating connection screw hole. Its head is clamped in the T-shaped groove on the outer end surface of the clamping seat and its inner end abuts against / fits with the bottom of the T-shaped groove.

6. The three-jaw flexible floating chuck according to claim 1, wherein The profiling template adopts a rectangular cylindrical structure. The slide rail conforms to the inner cavity of the profiling template and is in the shape of a rectangular block. The main body part of the slide plate conforms to the slide plate guiding groove and is in the shape of a plate. The inner wall of the profiling template outside the slide plate guiding groove is flat, adheres to the outside of the slide plate guiding groove, and together with the slide plate guiding groove forms a slide plate guiding hole for slide plate guiding cooperation.

7. The three-jaw flexible floating chuck according to claim 6, characterized in that The profiling guiding structure on the outer side surface of the slide plate includes a roller for profiling guiding and a pin shaft for profiling guiding. The outer diameters of the roller for profiling guiding and the pin shaft for profiling guiding are both smaller than the width of the L-shaped guiding groove.

8. The three-jaw flexible floating chuck according to claim 1, wherein The connection mode between the front end of the piston rod and the corresponding slide rail is a floating connection.

9. The three-jaw flexible floating chuck according to claim 8, characterized in that The rear end surface of the slide rail is provided with a T-shaped groove with a large inner diameter and a small outer diameter. The front end of the piston rod is provided with a spherical crown-shaped enlarged diameter part. The spherical crown-shaped enlarged diameter part is clamped in the T-shaped groove on the rear end surface of the corresponding slide rail, and its front end abuts against / fits with the bottom of the T-shaped groove.

10. External cylindrical grinder for small workpieces, provided with a grinding machine and a manipulator for loading and unloading the grinding machine, the grinding machine being provided with a headstock and a tailstock, characterized in that Both the headstock and the tailstock are provided with floating chucks and live centers. The floating chuck adopts the three-jaw flexible floating chuck described in any one of claims 1-9. The live center passes through the hollow of the floating chuck. The rotary cylinder body of the floating chuck and the end of the live center are respectively fixedly installed on the spindles of their respective headstocks or tailstocks.

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