Mold clamping device

An internal circulation direct hydraulic two-plate clamping device comprising

• a stationary plate (1),
• a movable plate (2),
• a mold-clamping cylinder (3) comprising a cylinder body (7), a piston rod (5),
• a piston (6), and a logic valve, and
• a mold-moving cylinder,
• wherein the piston rod (5) has an extension end that is connected with the movable mold plate (2) and an opposite end that is connected with the piston (6) in the cylinder body (7) and provided with a circular shaft (5.1),
• wherein a spool (10) having a shaft sleeve (11) at one end is provided, the circular shaft (5.1) of the piston rod being arranged slidablely in the inner chamber of the shaft sleeve (11), the inner chamber of the shaft sleeve (11) defining a controlling chamber (16) with the end surface of the circular shaft (5.1),
• wherein the piston (6) comprises a middle segment (6.2) provided with a pressure chamber (15), a rear segment (6.3) provided with a valve seat (12) having a center hole (24), and a front segment (6.1), wherein when the front segment (6.1) is connected with the opposite end of the piston rod (5), the circular shaft (5.1), the spool (10), the shaft sleeve (11) and the valve seat (12) form the logic valve,
• wherein the pressure chamber (15), where the spool (10) and the shaft sleeve (11) are located, is communicated with the center hole (24) of the valve seat (12) and through a passage (19) with a rod chamber (21) that is separated from a non-rod chamber (22) by the piston (6),
• wherein when the spool (10) is moved towards right or left, the oil flow between the rod chamber (21) and the non-rod chamber (22) can be blocked or opened.

A direct hydraulic two-plate clamping device comprising

• a stationary plate,
• a movable plate,
• a mold-moving cylinder, and
• mold-clamping cylinders comprising four cylinders (1, 2, 3, 4), each having a single out-extending piston rod,
• wherein the four mold-clamping cylinders (1, 2, 3, 4) have rod chambers (1A, 2A, 3A, 4A) that are communicated with each other through a connecting pipe (8),
• wherein three of the mold-clamping cylinders (1, 2, 3) are internal circulation cylinders, and one of the mold-clamping cylinders (4) is a cylinder comprising two oil chambers that are separated by the piston and not communicated with each other,
• wherein the rod chamber (4A) of the one of the mold-clamping cylinder (4) is communicated with the rod chambers (1A, 2A, 3A) of the three of the mold-clamping cylinders (1, 2, 3) and the non-rod chamber (4B) is communicated with atmosphere or an oil source.

A mold clamping device comprising a mold-clamping cylinder, wherein the mold-clamping cylinder comprises

• a cylinder body,
• a piston arranged within the cylinder body,
• a piston rod with one end inserted into the cylinder body and fixedly connected with one end of the piston, and
• a logic valve provided between the piston and the piston rod,
• wherein the piston comprises a communication passage provided at a side wall of the piston, and a center passage disposed in axial direction, the piston separating the cylinder body into a rod chamber and a non-rod chamber which are communicated by the connecting passage and the center passage,
• wherein the piston rod is provided with a high pressure oil passage along the axial direction,
• wherein the logic valve comprises a valve seat provided within the center passage of the piston, a spool provided between the valve seat and the piston rod, and a reset device that returns the spool back,
• wherein the valve seat is provided with a valve seat center passage that communicates the center passage of the piston with the non-rod chamber,
• wherein the end of the spool that is close to the valve seat has a sealing match with the valve seat center passage, and a controlling chamber that is communicated with the high pressure oil passage is provided between the spool and the piston rod,
• wherein when the spool is moved towards right or left, the oil flow between the rod chamber and the non-rod chamber can be blocked or opened.