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JP-2026074530-A - Hydraulic cylinder unit and clamping device

JP2026074530AJP 2026074530 AJP2026074530 AJP 2026074530AJP-2026074530-A

Abstract

[Problem] To provide a hydraulic cylinder unit that, in addition to suppressing sealing defects between the piston and the tie bar, can suppress the bias in the relative position of the central axes of the piston and the tie bar in a clamping device employing a cantilever structure of the tie bar. [Solution] The hydraulic cylinder unit comprises a cylinder tube having an oil chamber inside, a piston positioned in the oil chamber, and a piston rod fastened to the piston. The piston comprises a pressure-receiving portion that receives hydraulic pressure from the hydraulic fluid in the oil chamber, an intermediate portion connected to the pressure-receiving portion, and a fastening portion connected to the intermediate portion that is involved in fastening to the piston rod. The intermediate portion comprises a piston recess that is recessed radially outward from the pressure-receiving portion and the fastening portion. [Selection Diagram] Figure 2

Inventors

  • 加藤 直紀
  • 苅谷 俊彦

Assignees

  • ＵＢＥマシナリー株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (8)

  1. A cylinder tube with an oil chamber inside, A piston arranged in the oil chamber, The piston rod is fastened to the piston, The aforementioned piston is The oil chamber includes a pressure receiving section that receives hydraulic pressure from the hydraulic fluid, A fastening portion involved in fastening with the piston rod, The pressure-receiving portion and the fastening portion are connected along the central axis, The intermediate portion is a hydraulic cylinder unit having a piston recess that is recessed radially outward from the pressure-receiving portion and the fastening portion.
  2. The inner diameter DB in the intermediate portion is larger than the inner diameter DA in the pressure-receiving portion and the inner diameter DC in the fastening portion. The hydraulic cylinder unit according to claim 1.
  3. The aforementioned piston rod is It comprises a pressure-receiving part corresponding to the pressure-receiving part, an intermediate part connected to the pressure-receiving part and corresponding to the intermediate part, and a fastening part connected to the intermediate part and corresponding to the fastening part, The intermediate corresponding portion is provided with a rod recess that is recessed radially inward from the pressure-receiving corresponding portion and the fastening corresponding portion. The piston recess and the rod recess provide a hollow region spanning between the intermediate portion and the corresponding intermediate portion in the radial direction. The hydraulic cylinder unit according to claim 1.
  4. The hollow region in the piston is Outer radially from the fastening portion, extending beyond the boundary between the intermediate portion and the fastening portion to the fastening portion, The hydraulic cylinder unit according to claim 3.
  5. In the fastening portion, the diameter of the extended hollow region on the side closer to the central axis C has a tapered sleeve shape, which increases as it moves away from the intermediate portion. The hydraulic cylinder unit according to claim 4.
  6. A first packing is provided between the pressure receiving portion and the pressure receiving corresponding portion. A second packing is provided between the pressure receiving part and the cylinder tube. The hydraulic cylinder unit according to claim 3.
  7. A fixed mold plate that supports the fixed mold, A movable mold plate, which supports the movable mold, is positioned opposite the fixed mold plate, Multiple tie bars connecting the fixed panel and the movable panel, A clamping device comprising a hydraulic cylinder unit according to any one of claims 1 to 6, wherein a clamping force is applied between the fixed mold plate and the movable mold plate, and the tie bar is the piston rod.
  8. The fixed mold plate has a front surface facing the movable mold plate and a back surface opposite to the front surface. The cylinder tube housing the piston is positioned on the back side of the movable mold plate, detachably from the fixed mold plate. The clamping device according to claim 7.

Description

This invention relates to a mold clamping device applicable to injection molding machines and the like. In clamping devices, piston heads and rods (tie bars) with a screw-joint structure are well known. This is because manufacturing the piston head and rod (tie bar) as separate components reduces the outer diameter or length of each material, making them easier to obtain. For example, Patent Document 1 discloses a mold clamping device in which the piston head and tie bar are connected by a screw joint, and which has a structure that allows for efficient on-site assembly work. In this mold clamping device, a mold clamping cylinder mechanism (28) is provided on the side of the fixed mold plate (14). This mold clamping cylinder mechanism (28) comprises a ring nut (38) that is screwed onto the end of the tie bar (22), a mold clamping cylinder (32) formed on the back side of the fixed mold plate (14) opposite to the mold mounting surface, and a mold clamping piston (30) that is inserted into the mold clamping cylinder (32). After mold alignment, the mold clamping cylinder mechanism (28) supplies hydraulic fluid to a hydraulic chamber (34) formed between the mold clamping piston (30) and the mold clamping cylinder (32), thereby pulling the movable mold plate (16) towards the fixed mold plate (14) via the tie bar (22) and generating a mold clamping force. In the clamping device described in Patent Document 1, one end of the tie bar is supported and fixed by the movable mold plate, and the other end of the tie bar is inserted into the clamping piston of the clamping cylinder built into the fixed mold plate, after which the tie bar and the clamping piston are fixed together. In other words, the tie bar in the clamping device of Patent Document 1 has a portion at one end that does not have a ring groove for engaging with a half-nut mechanism, and instead has a portion for supporting one end of the tie bar with the movable mold plate. This structure prevents the tie bar from coming loose from the movable mold plate even when the movable mold plate is moved away from the fixed mold plate to its mechanical stroke limit, such as when changing molds; therefore, the tie bar is supported at both ends by the movable and fixed mold plates. Japanese Patent Publication No. 2006-321204Japanese Unexamined Patent Publication No. 49-30740 This is a side view showing a schematic configuration of an injection molding machine according to an embodiment.This is a cross-sectional view showing the configuration of a clamping cylinder unit according to an embodiment.This is a magnified view of a portion of Figure 2.This is a cross-sectional view showing the behavior of the piston during mold clamping and pressure building.This is a cross-sectional view showing the configuration of a clamping cylinder unit according to a modified example.This is a cross-sectional view showing the configuration of a clamping cylinder unit relating to other modifications. The embodiments of the present invention will be described below with reference to the attached drawings, using injection molding machine 1 as an example. In this embodiment, the tie bar 33 and piston 53 constituting the hydraulic cylinder unit 50 are fastened together. In addition, the hydraulic cylinder unit 50 has a cylinder tube 51 externally provided on the back surface 25B of the fixed mold plate 25, and is separable from the fixed mold plate 25. [Overall structure: See Figure 1] As shown in Figure 1, the injection molding machine 1 according to this embodiment includes a plasticizing section 10 and a molding section 20. For the sake of explanation, the front (F) and rear (R) of the injection molding machine 1 are defined as shown in Figure 1 and other figures. This definition is relative. [Plasticizing part 10: See Figure 1] The plasticizing unit 10 comprises a heating cylinder 11 and a discharge nozzle 13 provided at the front end of the heating cylinder 11. The plasticizing unit 10 also includes a screw rotatably mounted inside the heating cylinder 11 and a heater wrapped around the heating cylinder 11, although these are not shown in the figures. The pelletized raw material resin is supplied into the heating cylinder 11 via a raw material input hopper 15 provided in the heating cylinder 11. The screw is capable of moving forward and backward, as well as rotating in both forward and reverse directions, within the fixed position of the heating cylinder 11. The plasticizing unit 10 includes a drive source 17 for moving the screw forward or backward, and a drive source 18 for rotating the screw in both forward and reverse directions. The injection molding machine 1 performs resin injection molding by combining the forward or backward movement and forward or reverse rotation of the screw. [Molded section 20: See Figure 1] The molding unit 20 includes a fixed mold 21 whose position is fixed and a movable mold 23 which can move forward and backward relative to the fixed mold 21. In the m