Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/20—Other details, e.g. assembly with regulating devices
  • F15B15/26—Locking mechanisms
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/20—Other details, e.g. assembly with regulating devices
  • F15B15/24—Other details, e.g. assembly with regulating devices for restricting the stroke
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
  • F15B15/20—Other details, e.g. assembly with regulating devices
  • F15B15/26—Locking mechanisms
  • F15B15/261—Locking mechanisms using positive interengagement, e.g. balls and grooves, for locking in the end positions

Definitions

• Double acting hydraulic cylinder with axial locking device Double acting hydraulic cylinder with axial locking device.
• the invention relates to a double-acting hydraulic cylinder comprising a cylinder body closed at one end by a bottom and at the other end by a cylinder head, a guide piston mounted to slide in the cylinder body, a cylinder rod. integral with the guide piston and sealingly passing through the cylinder head, hydraulic means for actuating the jack rod and mechanical locking means for the jack rod in a predetermined extension position.
• jacks are used to move parts or tools, and these parts or tools must be kept in a fixed position for the duration of an operation.
• each mold element is fixed to the end of a cylinder rod and the actuation of the cylinder rod causes a translation of the element.
• the movable element is immobilized on a fixed frame by means of a pin accommodating in a bore formed in the element and the frame , this bore having a direction perpendicular to the axis of the cylinder rod.
• This spindle is also manipulated by a second double-acting cylinder.
• DE 12 57 583 discloses a hydropneumatic cylinder in which: a) the cylinder body has two coaxial cylindrical walls of different internal diameters, connected by a frustoconical annular section, the cylindrical wall having the largest diameter being disposed on the side of the head cylinder and the cylindrical wall having the smallest diameter serving to guide the guide piston, b) the actuator rod has between the guide piston and the cylinder head an annular protuberance having a diameter at most equal to the diameter of the cylindrical wall having the smallest diameter, said protuberance being disposed in line with the cylindrical wall having the largest diameter, in the predetermined extension position of the jack rod, c) the guide piston comprises means which put the two in fluid communication sides of said guide piston, d) an annular piston is disposed on the portion of cylinder rod located between the guide piston and the annular protuberance, this annular piston being capable of sliding in leaktight manner on the cylindrical wall having the smallest diameter and being capable of sliding in leaktight manner on said portion of piston rod under the action of the pressure agent
• the narrowed end of the annular piston is frustoconical and ends in a flat front face.
• the means for radially moving the locking members comprise bevelled pins axially passing through the annular protuberance and the bevels of which are disposed between the locking members and move them apart when these pins come to press against the cylinder head in the position of maximum extension of the cylinder rod.
• the locking members are in abutment on the frustoconical annular section of the cylinder body and on the tapered narrowed end of the annular piston. This is why a spring is provided in this document between the annular piston and the guide piston.
• This spring must exert a considerable force to avoid a total or partial unlocking of the jack when the jack rod receives forces during an injection molding operation.
• the bevelled pins have a given length, which does not allow a subsequent modification of the length of the cylindrical wall of larger diameter for adjusting the extension of the jack rod during injection molding.
• the pressures of the fluidic agent must be sufficient to compensate for the forces of the spring.
• One of the aims of the invention is to propose a double-acting cylinder which makes it possible to position a mold element in a precise position and to collect external compressive forces exerted on the cylinder rod during an operation of injection molding for example.
• Another object of the invention is to provide a double-acting cylinder whose piston rod can be immobilized mechanically and precisely in a predetermined extension position.
• the hydraulic cylinder according to the invention is characterized in that the narrowed end section of the annular piston is cylindrical and is terminated by a conical surface which is intended to cooperate with a conical surface of the members locking in order to bias them radially outwards, when the pressure agent acts on said annular piston in the direction of extension of the jack rod.
• the bearing surfaces can be appreciable, and the compressive forces exerted axially on the head of the cylinder rod can be taken up only by the locking members, without the aid of the pressure agent.
• the locking members comprise, radially outward, conical surfaces which cooperate with the frustoconical section of the cylinder body in the locking position.
• the locking members are constituted by two half-rings.
• the jack rod In order to facilitate maintenance of the jack in the event of buckling of the jack rod, the jack rod consists of two separable cylindrical parts, connected by screwing, one of which has the annular protuberance and the portion of jack rod on which is mounted the annular piston and the other of which slides in the cylinder head.
• the cylinder body advantageously consists of two coaxial parts, one of which, external, comprises the cylinder head, means of attachment to a frame, the connections to a source of fluid, and a cylindrical outer wall having an internal thread, and the other, internal one, comprising the bottom of the cylinder body and the body of the cylinder chamber, which has an external thread intended to cooperate with said internal thread in order to allow adjustment of the predetermined extension position relative to the frame, internal conduits being formed in said two parts between the fittings and the ends of the cylinder chamber.
• This arrangement has an additional advantage. Because the fittings are arranged on the external part fixed to the frame, the external hydraulic fluid supply and exhaust conduits do not undergo any modification during adjustment. They can be constituted by rigid metallic conduits in place of flexible conduits.
• FIG. 1 is a section on a plane passing through the axis of the cylinder d 'A cylinder according to the invention; the upper part of this figure shows a half-section of the cylinder rod in the maximum retraction position and not locked, while the lower part of this figure shows a half-section of the cylinder rod in the locked position;
• Figures 2a to 2e show various positions of the cylinder rod in its cylinder when it is subjected to deployment between the maximum retraction position and the locking position;
• Figure 3 shows in perspective a locking half-crown;
• Figure 4 is an axial view of a locking half-crown in the locking position; and
• Figure 5 is a section of a half-crown along the line VV of Figure 4.
• a double-acting hydraulic cylinder which comprises a cylinder body 2 closed at one end by a bottom 3 and at the other end by a cylinder head 4 which has a bearing 5 with an orifice 6 of axis X.
• a piston 7 is fixed to the internal end 8 of a cylinder rod 9 passing through the orifice 6 with interposition of seals 10.
• the cylinder body 2 is made up of two coaxial parts 2a, 2b of axis X which fit into each other.
• the external part 2a is in the form of a rigid tank, the cylindrical peripheral wall 11 of which has an internal thread 12, and the bottom of which is fitted with the bearing 5.
• the internal part 2b is in the form of an inverted tank whose wall device 13 has an external thread 14 and the bottom of which forms the bottom 3 of the cylinder body 2.
• the internal thread 12 and the thread 14 have identical diameters so that they cooperate together to axially fix the internal part 2b in the external part 2a . Seals 15 are interposed between the external part 2a and the internal part 2b.
• a nut 16 and a screw 21 deposited in a bore 18 make it possible to immobilize in rotation the internal part 2b relative to the external part 2a.
• the cylindrical peripheral wall 11 of the outer part 2a is equipped with connectors 17 and 19 for the connection of supply and exhaust conduits for a pressure agent, preferably oil.
• the connector 17 communicates with the end of the internal cavity of the cylinder body 2 located in the vicinity of the bearing 5 by a conduit 20 formed in the cylindrical peripheral wall 11.
• the connector 19 communicates by a conduit 22 formed in the cylindrical peripheral wall 11 with an annular chamber 23 formed between the external 2a and internal 2b parts in the cylindrical peripheral wall 11 of the peripheral wall 13.
• a conduit 24 formed in the peripheral wall 13 of the internal part 2b places the annular chamber 23 in communication with the end of the internal cavity of the cylinder body 2, situated in the vicinity of the bottom 3.
• the external part 2a is further provided with fixing means on a frame, these fixing means not being shown in the drawings for the sake of clarity .
• the internal part 2b can thus be positioned axially adjustable in the fixed external part 2a.
• the connections 17 and 19 are thus fixed relative to the frame which also supports the source of pressure agent.
• the internal cavity of the inner part 2b is delimited by two cylindrical walls of axis X of different diameter, connected by a frustoconical wall 25 of axis X, the cylindrical wall 26 of smaller diameter is disposed on the side of the bottom 3, and the cylindrical wall 27 of larger diameter is disposed on the side of the opening 28 of the internal part 2b, that is to say on the side of the cylinder head 4.
• the piston 7 is slidably mounted in the cylindrical wall 26 having the smallest diameter, with possible interposition of a seal 29. It further comprises through orifices 30, of axis X, which put the two faces of the fluid in communication.
• the cylinder rod 9 is also made in two parts, namely an external part 9a which slides in the bearing 5 and an internal part
• the external part 9a is terminated inside the cylinder body 2 by a thread 31 which cooperates with a thread formed at the end of the internal part 9b opposite the piston 7.
• the internal part 9b comprises three sections of different diameter, namely a section 33 having a diameter at most equal to the diameter of the cylindrical wall 26 having the smallest diameter, located around the above-mentioned thread, a middle section 34 having a diameter equal to about half the diameter of the cylindrical wall 26, and a narrowed section constituting the end 8 on which the piston 7 is mounted.
• the large diameter section 33 is delimited axially by two front walls 35, 36 which extend radially outwards.
• the front wall 35 in abutment against the cylinder head 4, defines the maximum possible extension of the jack rod 9.
• the front wall 36 disposed opposite the piston 7 axially delimits with the latter an annular chamber 37 surrounding the middle section 34.
• This annular chamber 37 houses, on the one hand, a stage annular piston 40 having an inside diameter equal to the diameter of the middle section 34 and an outside diameter equal to the diameter of the cylindrical wall 26 having the smallest diameter and, on the other hand part, two locking half-rings 41a, 41b, shown in detail in FIGS. 3 to 5.
• Each half-ring 41a, 41b is delimited radially by a portion of external cylindrical wall 42 having a diameter equal to the diameter of the cylindrical wall 26, an inner cylindrical wall portion 43 having a diameter equal to the diameter of a narrowed cylindrical end portion 44 of the annular piston 40, and axially, on the one hand, by a front wall 45 bearing against the front wall 36 of section 33 and, on the other hand, by two frustoconical walls 46 and 47 located opposite the piston 7.
• the annular piston 40 is interposed between the half-rings 41a, 41b and the piston 7.
• the cylindrical narrowed end 44 of the annular piston is terminated by a conical surface 48 which cooperates with the frustoconical wall 46
• the cylindrical narrowed end 44 of the annular piston 40 is connected to the external cylindrical wall of this annular piston 40 by a second conical wall 49.
• the length of the cylindrical narrowed re-end wall 44 is substantially equal to the width of the portion of inner cylindrical wall 43 of the half-rings 41a and 41b.
• the external diameter of the narrowed end 44 is substantially equal to half the sum of the diameters of the middle section 34 of the jack rod 9 and of the cylindrical wall 26.
• the extent of the wall frustoconical 25 of the cylinder body 2 is substantially equal to the extent of the frustoconical wall 47 of the half-rings 41a and 41b.
• Seals 50 are interposed between the annular piston 40, on the one hand, and the middle section 34 and the cylindrical wall 26, on the other hand.
• Figures 2a to 2e show different positions taken by the cylinder rod 9, the annular piston 40 and the half-rings 41a, 41b, when a pressure agent is introduced into the cylinder body through the conduit 24.
• the piston rod 9 is in the maximum retraction position.
• the pressure agent is introduced through the connector 19, via the conduit 22, the chamber 23 and the conduit 24, the conduit 20 is exhausted.
• the pressure PI applies to the two faces of the piston 7. Since the half-rings 41a and 41b cannot deviate radially, the annular piston 40 remains stationary relative to the middle section 34.
• the cylinder rod 9 is moved to the left, as shown in Figure 2b.
• the cylindrical narrowed portion 44 of the annular piston 40 slides along the portions of internal cylindrical walls 43 of the half-rings 41a, 41b, and the frustoconical wall 46 of the half-rings comes bearing against the frustoconical wall 49 of the annular piston 40. If the extension movement of the cylinder rod 9 is continued, the half-crowns 41a and 41b slide along the cylindrical wall 27 of large diameter, until that the front face 35 of the section 33 of large diameter comes to press against the cylinder head 4.
• annular piston 40 moves towards the straight until the frustoconical faces 46 and 47 of the half-rings 41a and 41b come into abutment respectively against the frustoconical wall 48 of the annular piston 40 and against the frustoconical wall 25 of the cylinder body 2.
• the half-crowns 41a and 41b are further immobilized radially between the cylindrical narrowed end portion 44 of the annular piston 40 and the cylindrical wall 27 having the largest diameter of the cylindrical body 2, as shown in FIG. 2e.
• piston 7 is used only for guiding and centering the piston rod 9 and for abutment on the annular piston 40.
• the seals 10 play only the role of sliding means and not a role of seal.
• the large diameter section 33 of the internal part 9b of the cylinder rod 9 has on its front face 36 an annular cavity 51 in the form of a wedge, in which is housed the end of the narrowed part 44 of the annular piston when the half crowns 41a and 41b are in the locked position.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Actuator (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=8851727

Family Applications (1)

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• 2000
  • 2000-06-27 FR FR0008226A patent/FR2810701B1/fr not_active Expired - Fee Related
• 2001
  • 2001-06-27 WO PCT/FR2001/002030 patent/WO2002001079A1/fr not_active Application Discontinuation
  • 2001-06-27 US US10/311,285 patent/US6782799B2/en not_active Expired - Fee Related
  • 2001-06-27 CA CA002413734A patent/CA2413734A1/en not_active Abandoned
  • 2001-06-27 CN CN01811666A patent/CN1439080A/zh active Pending
  • 2001-06-27 RU RU2002134465/06A patent/RU2002134465A/ru not_active Application Discontinuation
  • 2001-06-27 AU AU2001270671A patent/AU2001270671A1/en not_active Abandoned
  • 2001-06-27 BR BR0112192-8A patent/BR0112192A/pt not_active IP Right Cessation
  • 2001-06-27 CZ CZ20024001A patent/CZ20024001A3/cs unknown
  • 2001-06-27 JP JP2002505972A patent/JP2004502099A/ja active Pending
  • 2001-06-27 KR KR1020027017891A patent/KR20030020313A/ko not_active Application Discontinuation
  • 2001-06-27 PL PL35993601A patent/PL359936A1/xx unknown
  • 2001-06-27 EP EP01949537A patent/EP1295044A1/fr not_active Withdrawn

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