Full-automatic floating chuck and end face cylindrical grinding machine suitable for locomotive axle

Abstract

The utility model relates to a full-automatic floating chuck suitable for a locomotive axle and an end face cylindrical grinding machine. The floating chuck adopts a rotary oil cylinder of a hollow structure and is provided with a plurality of piston rods, the piston rods are distributed at equal intervals, a hollow rotating disc is arranged on the front side of the oil cylinder, the front end of each piston rod is flexibly connected with the rotating disc, a plurality of eccentric grooves are formed in the inner circle face of the rotating disc, and balls and thrust springs located on the circumferential rear sides of the balls are arranged in the eccentric grooves. The depth of the groove bottom of the eccentric groove located in the moving range of the balls is gradually reduced from back to front. A grinding machine headstock and a grinding machine tailstock of the grinding machine adopt the floating chuck and are provided with live centers. The floating chuck can effectively avoid hindering feeding and discharging of a mechanical arm, effectively avoid hindering grinding of the end face of a workpiece, effectively avoid hindering jumping of the center of the workpiece and effectively avoid scratching the surface of the workpiece, and is better suitable for machining of the outer circle of the end face of the workpiece such as a locomotive axle.

Description

Technical Field

[0001] The utility model relates to a full-automatic floating chuck adapted to a locomotive axle and an end face and outer circle grinding machine for a locomotive axle adopting such a floating chuck, belonging to the technical field of machinery. 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 worktable, 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; through the ratchet and the energy storage device, three chuck jaws rotate bidirectionally along their respective positioning shafts, and the claw part of the chuck jaw is an eccentric arc; there is a gap between the inner hole and both sides of the floating disk 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 claw 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 claw 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, and 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, a large clamping force, convenient adjustment, good repeatability and reproducibility, fast action response, no indentation on the workpiece by a set of asymmetric arc chuck jaws, and a long service life.Chinese Patent Document CN113878495A discloses a floating jaw chuck for a grinding machine, including a base. An installation groove is formed on the base. The installation groove has a "convex" structure. A jaw is arranged in the installation groove. The jaw 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. At the same time, when adjusting the angle of one eccentric cam, the angles of the other eccentric cams will also change synchronously, facilitating the loading of the workpiece. These prior arts each have their own characteristics and are respectively applicable to their respective suitable occasions. However, there are still certain limitations. Especially with the continuous improvement of production efficiency in the modern machining industry, more and more customers require high-efficiency cylindrical grinding machines for end faces, which require automatic loading and unloading with a manipulator on a fully automatic production line. At the same time, it is also required that a cylindrical grinding machine for end faces can complete the grinding of both end faces and the outer circle part of the workpiece after one clamping. The above prior arts still need to be further improved in terms of how to avoid interfering with the loading and unloading of the manipulator, how to avoid interfering with the grinding of the workpiece end face, how to avoid interfering with the center runout of the workpiece, and how to avoid scratching the workpiece surface, so as to better adapt to the end face and outer circle machining of workpieces such as locomotive axles. Summary of the Invention

[0003] The object of the present invention is to provide a fully automatic floating chuck and grinding machine that can better adapt to the end face and outer circle machining of workpieces such as locomotive axles.

[0004] The technical solution of the present invention is: A fully automatic floating chuck adapted to a locomotive axle is provided with an oil cylinder. The oil cylinder is provided with a rotary cylinder body (referred to as the cylinder body for short) and an annular piston (referred to as the piston for short) that conforms to the inner cavity of the rotary cylinder body (cylinder body). A plurality of piston rods are provided on the annular piston. The piston rods are equally spaced (equiangularly spaced). A hollow (provided with a central through hole) turntable is provided on the front side of the oil cylinder. The front ends of the piston rods are all flexibly connected to the turntable. A plurality of eccentric grooves are provided on the inner circular surface of the turntable. A ball and a thrust spring located at the rear side of the ball in the circumferential direction (the reverse side of the clamping direction, that is, the reverse side of the relative movement direction of the ball in the eccentric groove during the clamping process) are provided in the eccentric groove. The front end of the thrust spring is connected to / pressed against the ball (the rear side of the ball). The depth of the bottom of the eccentric groove within the movable range of the ball (the radial distance from the bottom of the groove to the inner circular surface of the turntable, or the groove depth) gradually decreases from the rear to the front (from the rear to the front in the clamping direction).

[0005] The number of the piston rods is preferably six, and other numbers of piston rods can also be set according to actual needs.

[0006] The number of the eccentric grooves is preferably the same as that of the piston rods (for example, six), and corresponds to each piston rod respectively.

[0007] The two oil circuit interfaces of the oil cylinder (the rod chamber interface and the rodless chamber interface, which can be respectively called 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, which can be respectively called 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).

[0008] Further, the rotary joint is rotatably installed on the outer side of the cylinder block.

[0009] Further, a check valve (including a check valve group) with a self-locking function is provided in the hydraulic control system.

[0010] Preferably, a pin shaft perpendicular to the piston rod (perpendicular to the central axis of the piston rod) is provided at the outer end of the piston rod, a rotary table pin shaft hole corresponding to each pin shaft is provided on the rotary table, the pin shaft is inserted into the rotary table pin shaft hole, and a flexible spacer sleeve is provided between the two (between the pin shaft and the rotary table pin shaft hole), thereby realizing the flexible connection between the front end of the piston rod and the rotary table.

[0011] For example, U-shaped mounting structures with openings facing outward corresponding to each piston rod are provided on the outer edge of the rotary table, the rotary table pin shaft holes are arranged on both sides of the U-shaped mounting structure, piston rod pin shaft holes are provided at the outer ends of the piston rods, and the pin shaft passes through the piston rod pin shaft holes of the corresponding pistons and is respectively inserted into the rotary table pin shaft holes located on both sides of the corresponding U-shaped mounting structure.

[0012] Preferably, the piston rod pin shaft holes (the axes of the pin shaft holes) provided on the piston rod (at the outer end of the piston rod) are perpendicular to the piston rod (the axis of the piston rod) and perpendicular to the radial direction passing through the center of the pin shaft hole (the direction of the straight line perpendicular to and intersecting with the central axis / axis extension line of the cylinder block), and the axes (or central axes) of the rotary table pin shaft holes on the U-shaped mounting structure overlap with the axes of the piston rod pin shaft holes on the corresponding piston rods (are on the same straight line).

[0013] Preferably, the pin shaft is in axial sliding fit with the piston rod pin shaft hole on the corresponding piston rod (the central axis direction of the pin shaft or the pin shaft hole).

[0014] Preferably, the eccentric groove is a groove with a constant width. The main parts of the two side groove walls are in the shape of parallel planes, and its width is adapted to the size of the ball. Generally, it can be slightly larger than the diameter of the ball to allow the ball to roll back and forth (front and back in the circumferential direction) in the groove under the limitation of the two side groove walls of the ball without shaking left and right (in the axial direction of the turntable).

[0015] Preferably, on the groove walls on both sides of the groove opening of the eccentric groove, there are constricted step platforms (step structures capable of forming constrictions), whereby the width of the groove opening is smaller than the width of the groove (the main part), and a part of the ball is allowed to expose from the groove opening but not the whole ball (that is, the width of the groove opening is smaller than the diameter of the ball), so as to allow the ball to expose from the groove opening and contact the workpiece.

[0016] Preferably, the ball is an elastic ball (or a flexible ball).

[0017] The end face external cylindrical grinder adapted to the locomotive axle includes a grinder (or a grinder body) and a manipulator for loading and unloading the grinder. The grinder is provided with a headstock and a tailstock. Both the headstock and the tailstock are provided with floating chucks and live centers. The floating chuck adopts any full-automatic floating chuck adapted to the locomotive axle disclosed by the present utility model. The live center is a live center and 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 main shafts (the headstock main shaft or the tailstock main shaft) of their respective headstocks or tailstocks.

[0018] The beneficial effects of the present utility model are as follows: Since the chuck adopts a hollow structure, it can cooperate with the live center to form a workpiece clamping mechanism and jointly implement the clamping of the workpiece. The rotary oil cylinder can be directly installed on the rotary main shafts of the headstock and the tailstock, adapting to the operation mode of alternately driving the workpiece by the headstock and the tailstock; since there are no jaws but the ball is used for clamping, and at the same time the ball material is changed from metal to polyurethane or POM, it has the characteristics of flexible clamping and not scratching the workpiece, and can also automatically adapt to the shape of the workpiece to avoid over-positioning; since the ball is provided, the elastic ball can roll on the eccentric circular raceway to realize the functions of clamping the workpiece and self-locking; since a hydraulic control one-way valve with a self-locking function is provided, the self-locking in the relevant state is realized; the full-automatic function is realized. When loading and clamping, there is no need for manual or other auxiliary settings to axially move the workpiece, nor is it necessary to manually adjust the jaws to calibrate the center of the workpiece.

[0019] The floating chuck of the present utility model can effectively avoid interfering with the loading and unloading of the manipulator, effectively avoid interfering with the end face grinding of the workpiece, effectively avoid interfering with the center runout of the workpiece, effectively avoid scratching the surface of the workpiece, and better adapt to the end face external cylindrical processing of workpieces such as locomotive axles. Description of the Drawings

[0020] Figure 1It is the front view schematic diagram of the floating chuck of the present utility model (X-X cross-sectional view, clamping state);

[0021] Figure 2 It is the top view schematic diagram of the floating chuck of the present utility model (Y-Y cross-sectional view, released state);

[0022] Figure 3 It is the side view schematic diagram of the floating chuck of the present utility model (Z-direction view);

[0023] Figure 4 It is the structural schematic diagram of the quick maintenance and adjustment mechanism of the floating chuck related to the present utility model;

[0024] Figure 5 It is the kinematic diagram of the floating chuck of the present utility model;

[0025] Figure 6 It is the principle schematic diagram of the hydraulic control system of the floating chuck of the present utility model;

[0026] Figure 7 It is the state schematic diagram of the floating chuck cooperating with the manipulator for loading and unloading;

[0027] Figure 8 It is the structural schematic diagram of the six-bar piston 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;

[0028] Figure 9 It is the structural schematic diagram of the flexible clamping mechanism related to the present utility model;

[0029] Figure 10 It is the structural schematic diagram of the floating connection mechanism related to the utility model, where the left figure is the front view of the relevant part, and the right figure is the side view;

[0030] Figure 11 It is the layout diagram of the grinding machine related to the present utility model;

[0031] Figure 12 It is the partial enlarged view of the floating connection and flexible clamping 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. Specific embodiments

[0032] I. Composition of the floating chuck

[0033] See Figures 1-3 , the full-automatic six-bar piston floating chuck (referred to as the floating chuck) of the present utility model mainly includes the following parts: A. Hollow oil cylinder and rotary joint; B. Six-piston-rod hollow piston; C. Floating connection mechanism; D. Flexible clamping mechanism.

[0034] The hollow oil cylinder and the rotary joint (Part A) include: 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.

[0035] The six-piston-rod hollow piston (Part B) includes: piston B1, piston rods B2 (six pieces), nuts B3, sealing ring B4, and sealing ring B5.

[0036] The floating connection mechanism (Part C) includes: pin shaft C1, rubber spacer C2, and snap ring C3.

[0037] The flexible clamping mechanism (or flexible clamping actuator, Part D) includes: balls (specifically, flexible balls) D1, spring D2, turntable D3, screw D4, and end cover D5.

[0038] In addition, other related parts are involved during the working process: workpiece E1 (e.g., locomotive axle), live center E2, headstock spindle E3, and grinding wheel E4.

[0039] Figure 1 and Figure 2 respectively show the clamping state and the released state of the floating chuck. In the released state, after the oil cylinder drives the turntable D3 to retract, it moves 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 / hindrance.

[0040] The cylinder block A3 of the slewing cylinder has a hollow structure in the shape of a ring (with a ring-shaped cross-section), and in the center is a passage (or hollow, usually a cylindrical passage, adapted to the shape of the center point, allowing the live center to pass through to perform corresponding functions) for setting the live center. The cylinder end covers A1 and the sealing rings at various places can be set according to the conventional cylinder design, and the area range / interface between the cylinder block (main part) and the end cover of the cylinder is divided on the entire cylinder block 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 cylinder. Six piston rods are evenly distributed on the same circumference, pass through the respective through holes on the cylinder end cover A1, and its right end (located inside the cylinder) is fixedly installed on the piston by a threaded connection method (a fastening nut can be set), and its left end (located outside the cylinder) is provided with a piston rod pin shaft hole. On the outside of the turntable D3, there extends an installation plate group for connecting the pin shaft, which together with the turntable (main part) forms a U-shaped installation structure. Each installation plate group includes two parallel installation plates (or installation ears), and the two installation plates are respectively located on both sides of the corresponding pin shaft in the circumferential direction. The turntable pin shaft holes corresponding to the pin shaft are set on the installation plates. The pin shaft C1 is inserted through the corresponding piston rod pin shaft hole and the turntable pin shaft hole, and both ends respectively protrude from the outer ends of the turntable pin shaft holes on the corresponding installation plates, and are axially fixed (position-limited) by a circlip C3. The rubber spacer sleeve C2 is set (filled) between the pin shaft and the turntable pin shaft hole, and is in a certain compressed state. Through the deformation of the rubber spacer sleeve, the pin shaft is allowed to make a certain amount of axial and radial movement relative to the turntable pin shaft hole, thereby realizing the flexible connection between the pin shaft and the turntable. There can be a small gap or no gap between the pin shaft and the piston rod pin shaft hole to allow the pin shaft to have a certain amount of axial sliding relative to the piston rod pin shaft hole. The center positions of the piston rod pin shaft holes are located on the same circumference (or circle), and this circumference (the plane where it is located) is perpendicular to the central axis (or axis) of the floating chuck / cylinder. The central axis of the piston rod pin shaft hole is located on the tangent line of the circle where the center of the piston rod pin shaft hole is located. The axis (central axis) of the turntable pin shaft hole overlaps (is located on the same straight line) with the axis (central axis) of the corresponding (pin shaft passing through the same one) piston rod pin shaft hole, and is perpendicular to the two side planes (two large surfaces) of the corresponding installation plate.

[0041] On the inner circle (radial inner surface, or inner cylindrical surface, or inner circular surface) of the turntable D3, a number of eccentric grooves (for example, 6, corresponding to 6 piston rods) serving as eccentric circular raceways for ball bearings are provided. The groove walls on the front and rear sides (axial two sides) of the eccentric groove can be planes, perpendicular to the central axis of the floating chuck / cylinder, and the groove bottom is an eccentric curved surface, usually in the shape of a cylindrical surface parallel to the central axis of the floating chuck / cylinder. A ball bearing D1 and a thrust spring located on one side (circumferential one side) of the ball bearing are provided in the groove. The groove depth (radial dimension from the groove bottom to the inner circle of the turntable) on the side of the ball bearing (within the moving range of the ball bearing) gradually decreases (gradually decreases from the side near the thrust spring to the side far from the thrust spring), and is roughly a cylindrical surface with an eccentric distance between its central axis and the central axis of the turntable. The radius of this cylindrical surface is preferably greater than the radius of the inner circle of the turntable. The width of the eccentric groove is similar to (slightly larger than) the diameter of the ball bearing to allow the ball bearing to roll in the eccentric groove. On the groove walls on both sides of the groove opening (the groove opening of the eccentric groove), a constriction step (step for forming a constriction structure) is provided, so that the width of the groove opening is smaller than the width of the groove (main body part), and allows a part of the ball bearings to protrude from the groove opening but does not allow all the ball bearings to escape (that is, the width of the groove opening is smaller than the diameter of the ball bearing). Appropriate groove bottom shapes, groove depths, constriction steps, etc. can be set so that the ball bearings can move in the eccentric groove. The size of the part of the ball bearing protruding from the groove opening is limited by the groove depth at the corresponding part, so that the ball bearings can be respectively clamped and released (released) when rolling to different positions (for example, both ends of the moving range of the ball bearings).

[0042] Based on the convenience of machining the eccentric groove, the turntable can be divided into a turntable body (the main body part of the turntable) and an end cover D5 (or turntable cover plate). The turntable cover plate is located on the front side of the turntable body and is fixedly connected (for example, screwed / bolted) to the turntable body as a whole. The main part of the eccentric groove (the eccentric groove structure on the main body) is machined on the turntable body. The size of the end cover D5 should at least cover the eccentric groove structure on the turntable body to form the front groove wall of the eccentric groove. The constriction steps on the groove walls on both sides of the groove opening are respectively provided at the corresponding parts on the turntable body and the turntable cover plate.

[0043] The number of end covers D5 can be several, respectively arranged on (covering) the front sides of their corresponding eccentric grooves; or a large end cover D5 can be used to cover the front sides of all the eccentric grooves at the same time. The area of this large end cover (the area of its large surface) can be the same as that of the turntable (the turntable body part), so that the inner circular surface and the outer circular surface (radial outer surface, or outer cylindrical surface, or outer circle) of the end cover are completely aligned with the inner circular surface and the outer circular surface on the turntable body part to form a cylindrical surface with equal diameter.

[0044] The fixed connection of each relevant part can be achieved by means such as welding and threaded connection (for example, the fastening connection of connecting parts such as screws, bolts and nuts), etc. The mating method and mating clearance (if any) of each movable connection can be set according to actual needs. The connection and sealing of the oil circuit can be achieved by setting a sealing ring, etc. A rabbet or stepped connection / mating surface can be provided between the mutually connected parts according to actual needs.

[0045] II. Working principle of the floating chuck

[0046] 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 (alternatively, compressed air can be used to replace the hydraulic oil. In this case, the so-called oil cylinder can be regarded as / equivalently replaced by a cylinder), pushing the piston B1 to move leftward. The 6 piston rods B2 fixed on the piston B1 extend (to the left, in accordance with Figure 1 the indicated direction), and the 6 pin shafts C1 fixed on the piston rods B2 synchronously and flexibly drive the turntable D3 to move leftward through their respective rubber sleeves C2, and the workpiece E1 is sleeved (at this time, the 6 groups of balls D1 pressed out by the springs D2 in the turntable D3 are pushed back to the eccentric circular raceway by the workpiece E1), and the extension action is completed.

[0047] The spindle E3 of the headstock rotates clockwise (in accordance with Figure 3 the indicated direction). The 6 piston rods B2 flexibly drive the turntable D3 and the 6 balls D1 inside it to rotate through the rubber sleeves C2. The 6 balls D1 roll clockwise between the workpiece E1 and the eccentric circular raceway of the turntable D3, clamping the workpiece E1 from 6 directions, and the clamping action is completed.

[0048] During the clamping process, floating connection is carried out simultaneously. On the one hand, the turntable D3 floats relying on 12 rubber sleeves C2: axially, it floats through the elastic deformation of the 12 rubber sleeves C2; radially, it also floats through the elastic deformation of the 12 rubber sleeves C2. On the other hand, the 6 pin shafts C1 can slide on the 6 piston rods B2 respectively to achieve floating.

[0049] The 6 balls D1 can be made of materials with appropriate elasticity such as polyurethane or POM. They can be elastically deformed during the process of clamping the workpiece E1 to achieve flexible clamping.

[0050] During the process of the chuck clamping and holding the workpiece E1, the workpiece E1 has been centered by 2 live centers E2. Through the above 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.

[0051] III. Layout structure of the six-bar piston

[0052] Six groups of piston rods B2, pin shafts C1, balls D1 and springs D2 are evenly distributed within a 360° circumference (circumferentially evenly distributed). In addition, six groups (two in each group) of rubber bushings C2 and other parts are also circumferentially evenly distributed.

[0053] When the pin shaft C1 is installed, it needs to be inserted into the hole of the turntable D3 without obstruction, occupying a certain amount of space accordingly. To avoid interference, the pin shaft C1, the ball D1, and the rubber bushing C2 are arranged at an angle interval of 60°. There is also a certain distance or angular interval between the components in the same group according to actual needs. Similarly, to avoid interference, the oil circuits and interfaces of the screw A12 and the rotary joint A8 can be spaced at an angle of 15°.

[0054] According to the standards of the end face cylindrical grinder type spectrum, interference with the grinding wheel also needs to be avoided. Therefore, the radial space of the floating chuck is limited. Due to the need to configure a live center E2, the shape of the chuck must be hollow. In addition, the length of the live center E2 is limited (being too long will reduce the stiffness of the support and positioning), resulting in the axial space of the floating chuck being limited. In the limited space, in order to accommodate many mechanisms such as floating connection, flexible clamping, hollow oil cylinder, rotary joint, six-rod piston, and eccentric circular raceway, the above-mentioned staggered (spaced at a certain angle) layout is a necessary way, effectively avoiding these interferences.

[0055] IV. Regarding the quick adjustment mechanism of the floating chuck

[0056] See Figure 4 , since the floating chuck is applied in an automatic production line, it should be able to be quickly adjusted when changing workpieces to meet the functional requirements of the fixture for changing the clamping range. The structure of the floating chuck of the present utility model well meets this requirement. For example, by removing six groups of screws D4 and end covers D5, the vulnerable parts, the balls D1 and the springs D2, can be quickly replaced; by removing six groups of snap rings C3 and pin shafts C1, the vulnerable parts, the rubber bushings C2, can be quickly replaced.

[0057] In response to the change in the diameter size of the workpiece E1, by removing six groups of snap rings C3, the turntable D3 can be quickly replaced (the hollow hole diameter and the shape of the eccentric circular track are scaled accordingly).

[0058] V. The motion mode of the six-rod piston floating chuck

[0059] See Figure 5 , the floating chuck has six groups of compound slider mechanisms, which can achieve large axial stroke movement and small radial stroke movement (floating). By the movement and rotation of the turntable D3, it is ensured that the floating function is available when clamping the workpiece E1.

[0060] VI. The hydraulic control system of the floating chuck

[0061] See Figure 6, the hydraulic control system includes: oil pump F1, pressure reducing valve F2, pressure gauge F3, electromagnetic directional control valve F4, hydraulic control check valve F5 and oil cylinder F6.

[0062] Hydraulic control principle: The extension and retraction of the piston rod of the floating chuck are realized by switching the electromagnetic directional control valve F4, and the basic support stiffness of the floating chuck is realized by adjusting the pressure reducing valve F2 (the pressure gauge F3 can be observed). During the grinding process, if the external cylindrical grinder suddenly loses power, or the oil pump F1 is damaged resulting in insufficient pressure and other faults, the hydraulic control check valve F5 will lock the oil cylinder F6 to stop moving, avoiding potential safety hazards.

[0063] VII. Working mode of the floating chuck cooperating with the manipulator for loading and unloading

[0064] See Figure 7 , the relevant parts involved in the floating chuck cooperating with the manipulator for working include: headstock G1, floating chuck G2, tailstock G3, manipulator G4.

[0065] 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 external cylindrical grinding machines is increasing. It is required to cooperate with the manipulator for automatic loading and unloading on the fully automatic production line. Moreover, for an external cylindrical grinding machine, after one clamping, the two end faces and the outer cylindrical part of the workpiece are ground. Thus, the corresponding functions of the floating chuck of the present invention are required. 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 the two ends by the floating chuck G2 without scratching the clamping parts. When the manipulator G4 loads and unloads the workpiece, the floating chuck G2 is in the released position and does not interfere with the manipulator G4.

[0066] Since the floating chucks of this headstock and tailstock do not interfere with the operation of the manipulator, the manipulator can adopt any suitable existing technology and perform the loading and unloading operations according to the existing operation mode.

[0067] VIII. Structure and related characteristics of the floating chuck

[0068] 1. Six-rod hollow piston (see Figure 8 )

[0069] 1) Compared with the common standard oil cylinder with only 1 piston and 1 piston rod, the oil cylinder of the present invention adopts a piston with a hollow structure and 6 piston rods (which can be called a six-rod hollow piston). Since in the case of driving 6 piston rods to move respectively by 6 standard oil cylinders, it is impossible to ensure that each piston rod reaches the same speed and synchronization, and a synchronization mechanism and a speed regulation mechanism need to be set. However, by adopting the six-rod hollow piston of the present invention (according to actual needs, other numbers of piston rods can also be set), the synchronization of the six piston rods is fundamentally ensured, and there is no need to set a synchronization mechanism and a speed regulation mechanism.

[0070] 2) Compared with the closed (solid) structure of the standard oil cylinder, the oil cylinder end cover A1 and the oil cylinder body A3 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 oil cylinder end cover A1, which ensures the centering of the live center E2 to the workpiece E1 required by the cylindrical grinder.

[0071] 3) From the perspective of the processing technology, in order to ensure the smooth operation of the 6 piston rods B2, 6 through holes for assembling the 6 piston rods B2 can be machined on both the oil cylinder end cover A1 and the piston B1 simultaneously, ensuring the positional tolerance of the through holes relative to the center of the part.

[0072] 2. Flexible clamping mechanism (see Figure 9 and Figure 12 )

[0073] 1) Six balls D1 clamp the workpiece E1 from six directions. The ball material is polyurethane or POM, which is elastic. Its hardness (Shore 50 - 80HA) is lower than the hardness of the workpiece (HRC40 - 60), and 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, scratches are likely to be generated during the clamping process due to the mutual sliding with the workpiece.

[0074] 2) The movement mode of the balls D1 is rolling, which is beneficial to clamping and protecting the workpiece surface; at the same time, it can automatically adapt to the shape of the workpiece and avoid over-positioning.

[0075] 3) The balls are 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 the jaws and the workpiece not easy to slide relative to each other.

[0076] 4) The swing bases of the six balls D1 are turntables D3. During the clamping process, they are linked to each other, which can better adapt and clamp the workpiece E1.

[0077] 5) Since the workpiece processed by the end face cylindrical grinder is centered by the two end centers, and the runout and dimensional tolerance of the outer circle surface both meet the processing requirements of the pre-grinding process (for example, 0.04mm). After the floating clamping action of the floating chuck, the six flexible balls D1 generate elastic deformation to clamp the workpiece. During the grinding process, sufficient clamping force is continuously maintained through hydraulic oil, and the configured hydraulic control check valve can achieve hydraulic locking to prevent fixture failures when the machine tool suddenly loses power.

[0078] 3. Floating connection mechanism (see Figure 10 and Figure 12 )

[0079] 1) Components involved: pin shaft C1, rubber bushing C2, snap ring C3, turntable D3, spring D2, and ball D1;

[0080] 2) Extension process: After the workpiece E1 is clamped by two live centers E2, its center is already aligned. When the turntable D3 extends, the ball D1 pressed out by the spring D2 is sleeved into the workpiece E1 along the chamfer (2×45°) at the end of the workpiece E1. At this time, the ball D1 floats with the spring D2 and finally adheres to the outer circle surface of the workpiece E1.

[0081] 3) Clamping process: The turntable D3 rotates clockwise, and the contact point between the eccentric circular raceway and the ball D1 continuously shrinks. The ball D1 floats under the action of three external forces (the acting forces respectively generated by the spring, the eccentric circular raceway, and the workpiece surface), and finally clamps the workpiece E1.

[0082] 4) Pivoting process: After clamping, the turntable D3 and the workpiece E1 are fixed as a whole. Six piston rods B2 pivot the turntable D3 and the workpiece E1 through 12 rubber bushings C2, and float with the elastic deformation of the rubber bushings C2.

[0083] 5) There are two places for floating connection:

[0084] i) Between the piston rod B2 and the turntable D3, there is a floating connection through the elastic body rubber bushing C2. During the extension action, the turntable D3 floats to facilitate the entry of the D1 ball into the workpiece E1 and plays a buffering role when the two come into contact. During the clamping action and the subsequent continuous pivoting of the workpiece E1, it avoids over-positioning of the piston rod B2 on the workpiece E1 and affects the machining accuracy.

[0085] ii) Between the D1 ball and the turntable D3, there is a floating connection through the spring D2. During the extension action, the D1 ball rolls in the space formed by the turntable D3 and the end cover D5 and finally clamps the workpiece E1. This floating connection facilitates the D1 ball to quickly adhere to the outer circle surface of the workpiece E1 and adapt to its shape.

[0086] 4. Rotary joint

[0087] A rotary joint is used to realize the oil circuit connection of the oil cylinder. Based on the outer circle of the oil cylinder block A3, two bearings A6 support the rotary joints A5 and A8 to make rotary motion, and both ends are sealed by two sealing rings A4, so that the oil pipes connected do not twist when the main shaft rotates.

[0088] 5. Related structures to prevent scratching and not affect runout

[0089] 1) When the manipulator automatically loads and unloads workpieces, the turntable D3 can quickly move away from the workpiece to facilitate the manipulator to load and unload workpieces, avoiding interference and collision accidents; when the manipulator leaves, it can also quickly complete the clamping action, reducing the manual operation of loading and unloading the clamp, lowering the labor intensity, and improving the processing efficiency.

[0090] 2) When replacing the workpiece, to adapt to the change of the outer diameter of the workpiece, the clamping range of the jaws can be adjusted (for example, from φ100 to φ150), quickly realizing the fixture adjustment and improving the processing efficiency.

[0091] 3) Six balls D1 clamp the workpiece. Compared with the existing double V-block chucks and three-cam chucks, in the floating chuck type, it is easy to adjust the jaws and will not damage the surface of the workpiece.

[0092] 4) When the balls D1 are clamping, due to the low hardness of the balls and the use of rolling clamping, it can avoid scratching the ground surface of the workpiece. Self-locking is formed on the eccentric circular raceway, and when the pressure of hydraulic or pneumatic suddenly drops, it can continue to move the workpiece E1. Because the rubber spacer C2 has the ability of elastic deformation, it will not affect the runout of the workpiece during the movement process (similar to a flexible coupling).

[0093] IX. Loading and clamping mechanism (or clamping mechanism) and grinding machine

[0094] 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 tailstock of the grinding machine. The grinding machine with such a loading and clamping mechanism is suitable for the external cylindrical and end face grinding of large workpieces such as locomotive axles, and can grind the two end faces and the external cylindrical part of the workpiece after one clamping.

[0095] Related components of the grinding machine: headstock G1, tailstock G3, left grinding wheel head G5, right grinding wheel head G6, left slide G7 and right slide G8. The headstock G1 and the tailstock G3 are both provided with a floating chuck G2 and a live center E2. It can complete the grinding process of the two end faces and the external cylinder of the axle in one clamping.

[0096] The present utility model can meet the following functional requirements:

[0097] 1) Allow the headstock and tailstock of the CNC external cylindrical and end face grinding machine to alternately drive the workpiece;

[0098] 2) When the manipulator loads and unloads workpieces, the chuck withdraws from the loading and unloading area to avoid interference;

[0099] 3) When the grinding wheel grinds the two ends of the workpiece, the chuck withdraws from the grinding area to avoid interference and the outer diameter is small enough;

[0100] 4) The chuck is hollow and the aperture is large enough to allow the matching of a live center, suitable for large-weight workpieces such as axles;

[0101] 5) Adopt flexible ball clamping. In the case where the surface of the workpiece has been ground, the jaws will not scratch the surface of the workpiece;

[0102] 6) An effective and reliable floating connection is provided in the chuck, which does not affect the center runout of the workpiece when driving the workpiece.

[0103] All directional indications (such as left, right, etc.) in this specification are only used to explain the relative positional relationship of each relevant component in a corresponding direction or the relative positional relationship in multiple directions under a certain specific posture or implementation mode, and do not constitute a limitation on the actual use direction. If this specific posture changes, then the directional indication will also change accordingly. Additionally, it can also be understood that the swapping of the relative positions in at least some directions (for example, the circumferential direction) does not prevent the implementation of the technical solution.

[0104] Each preferred and optional technical means disclosed in the present utility model, except as otherwise specifically stated and when one preferred or optional technical means is a further limitation of another technical means, can be arbitrarily combined to form several different specific implementation modes.

Claims

1. Fully automatic floating chuck suitable for locomotive axles, equipped with a cylinder, characterized by The oil cylinder is provided with a rotating cylinder body and an annular piston conforming to the rotating cylinder body, the annular piston is provided with a plurality of piston rods, the piston rods are distributed at equal intervals, a hollow turntable is provided on the front side of the oil cylinder, the front end of each piston rod is flexibly connected to the turntable, a plurality of eccentric grooves are provided on the inner circumferential surface of the turntable, balls and thrust springs located at the circumferential rear side of the balls are provided in the eccentric grooves, and the depth of the bottom of the eccentric grooves located within the movable range of the balls gradually decreases from back to front.

2. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 1, characterized in that The two oil circuit interfaces of the oil cylinder are connected to the two oil circuit interfaces of the hydraulic control system through respective swivel joints. The swivel joints are rotatably mounted on the outside of the cylinder body. A one-way valve with a self-locking function is provided in the hydraulic control system.

3. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 1, characterized in that The outer end of the piston rod is provided with a pin shaft perpendicular to the piston rod, and the turntable is provided with turntable pin shaft holes corresponding to each pin shaft respectively. The pin shaft is inserted into the turntable pin shaft hole, and a flexible spacer is provided between the two, thereby realizing a flexible connection between the front end of the piston rod and the turntable.

4. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 3, characterized in that The outer edge of the turntable is provided with a U-shaped mounting structure with an opening facing outward corresponding to each piston rod. The turntable pin shaft hole is arranged on both sides of the U-shaped mounting structure. The outer end of the piston rod is provided with a piston rod pin shaft hole. The pin shaft passes through the piston rod pin shaft hole of the corresponding piston, and the two ends are respectively inserted into the turntable pin shaft holes located on both sides of the corresponding U-shaped mounting structure.

5. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 4, characterized in that The piston rod pin hole arranged on the piston rod is perpendicular to the piston rod and perpendicular to the radial direction through the center of the pin hole, and the axis of the turntable pin hole on the U-shaped mounting structure is located on the same straight line as the axis of the piston rod pin hole on the corresponding piston rod.

6. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 4, characterized in that The pin shaft is axially slidably matched with the piston rod pin shaft hole on the corresponding piston rod.

7. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 1, characterized in that The eccentric groove is a groove of equal width, and the main parts of the groove walls on both sides are in the shape of planes parallel to each other.

8. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 7, characterized in that The groove walls on both sides of the groove opening of the eccentric groove are provided with shrinking steps.

9. The fully automatic floating chuck adapted for a locomotive axle as claimed in claim 1, characterized in that The balls are elastic balls.

10. An end face cylindrical grinder suitable for locomotive axles, comprising a grinder and a manipulator for loading and unloading the grinder, the grinder being provided with a headstock and a tailstock, characterized in that The headstock and tailstock are both provided with a floating chuck and a center. The floating chuck adopts the fully automatic floating chuck suitable for locomotive axles as described in any one of claims 1-9. The center is a live center, which 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 mounted on the main shaft of the headstock or tailstock where they are located.

Images