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KR-20260062303-A - Piston ram composition mounted concrete pump car and manufacturing method thereof

KR20260062303AKR 20260062303 AKR20260062303 AKR 20260062303AKR-20260062303-A

Abstract

The present invention comprises a polyurethane composition comprising 70 to 90 weight% of a polyurethane prepolymer and 10 to 30 weight% of a curing agent composition comprising 0.5 to 5 weight parts of non-reactive polydimethylsiloxane, wherein the polyurethane prepolymer forms urethane groups by reacting a polyol compound comprising a polyether polyol, a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol, or a mixture thereof with a polyisocyanate compound, and the curing agent comprises 1,4-butanediol, hydroquinone-bis-hydroxyethyl ether, 1,4-cyclohexanedimethanol, trimethylolpropane, aliphatic tetrole, 4,4'-methylenedianiline, 2,2',5-trichloro-4,4'-methylenediamine, naphthalene-1,5-diamine, ortho, meta and para-phenylenediamine, toluene-2,4-diamine, The present invention provides a composition for a piston ram of a concrete pump truck, comprising one or more of the following: dichlorobenzidine, diphenyl ether-4,4'-diamine, 4,4'-methylene-bis(3-chloroaniline), 4,4'-methylene-bis(3-chloro-2,6-diethylaniline), diethyl toluenediamine, tertiary butyl toluenediamine, dimethylthio-toluenediamine, trimethylene glycol di-p-amino-benzoate, 1,2-bis(2-aminophenylthio)ethane, and a methylenedianiline-sodium chloride complex.

Inventors

  • 김응석
  • 김태훈

Assignees

  • (주)오톡스

Dates

Publication Date
20260507
Application Date
20241029

Claims (4)

  1. A piston ram of a concrete pump truck characterized by comprising 70 to 90 weight% of a polyurethane prepolymer and 10 to 30 weight% of a curing agent composition as a polyurethane composition, wherein the curing agent composition comprises 0.5 to 5 weight parts of non-reactive polydimethylsiloxane.
  2. In claim 1, The above-mentioned polyurethane prepolymer is characterized by forming urethane groups by reacting a polyol compound, comprising a polyether polyol, a polyester polyol, a polycaprolactone polyol, and a polycarbonate polyol, or a mixture thereof, with a polyisocyanate compound, in a piston ram of a concrete pump truck.
  3. In claim 2, The above curing agent composition comprises 1,4-butanediol, hydroquinone-bis-hydroxyethyl ether, 1,4-cyclohexanedimethanol, trimethylolpropane, aliphatic tetrole, 4,4'-methylenedianiline, 2,2',5-trichloro-4,4'-methylenediamine, naphthalene-1,5-diamine, ortho, meta and para-phenylenediamine, toluene-2,4-diamine, dichlorobenzidine, diphenyl ether-4,4'-diamine, 4,4'-methylene-bis(3-chloroaniline), 4,4'-methylene-bis(3-chloro-2,6-diethylaniline), diethyl toluenediamine, tertiary butyl toluenediamine, dimethylthio-toluenediamine, trimethylene glycol di-p-amino-benzoate, A piston ram of a concrete pump truck characterized by being selected from 1,2-bis(2-aminophenylthio)ethane and a methylenedianiline-sodium chloride complex, either alone or in combination of two or more.
  4. A step of preparing a molten material by stirring a piston ram composition of a concrete pump truck according to any one of claims 1 to 3; and A method for manufacturing a piston ram of a concrete pump truck, characterized by including the step of manufacturing a piston ram by pouring the above-mentioned molten material into a preheated mold.

Description

Piston ram of a concrete pump car and manufacturing method thereof The present invention relates to a piston ram mounted on the cylinder of a concrete pump truck and a method for manufacturing the same. More specifically, it relates to a piston ram composition capable of preventing a decrease in durability and wear resistance by lubricating between the cylinder and the piston ram and supporting the piston ram to prevent deformation as much as possible, and a method for manufacturing a piston ram having such a composition. A concrete pump truck functions to pump concrete mixed in a ready-mix concrete mixer truck into a delivery cylinder and send the concrete to the desired pouring location. As illustrated in FIGS. 1 and 3 as prior art, the pumping operation in the delivery cylinder is performed by a pumping system composed of pairs that repeatedly perform suction and discharge strokes in mutually opposite directions. A piston ram is positioned within the cylinder of the pumping system, and the piston ram pumps concrete by reciprocating within the cylinder to suction and discharge it. Such a piston ram is made of metal and consists of a body portion and a rubber sealing portion mounted on the outer circumference of the metal body portion, which contacts the inner surface of the cylinder. The diameter of the sealing part is larger than the diameter of the inner surface of the cylinder (for example, the inner surface of the cylinder is 230 mm, and the outermost diameter of the sealing part is 238 mm), so it is forcibly pressed into the inner surface of the cylinder when mounted. As a result, when the piston ram reciprocates, it comes into strong contact with the inner wall of the cylinder, and one side also comes into contact with concrete, so significant wear resistance is required. As prior art, FIGS. 1 to 3 are disclosed in Published Utility Model Publication No. 20-2000-0013241, Published Patent Publication No. 10-2024-0111202, and Registered Patent Publication No. 10-2077309, and show a piston ram structure for pumping concrete that was used in conventional concrete pump trucks. In the past, a material with better wear resistance than general rubber was used for the piston ram, specifically for the sealing part of the piston ram. However, even so, wear caused by strong contact with the inner wall of the cylinder and the incorporation of concrete located on one side of the piston ram accelerated the progression of wear. Due to such wear, a gap develops between the piston ram and the inner wall of the cylinder. This gap causes the concrete mixture to leak through the piston ram, which poses a problem as it damages not only the cylinder but also the peripheral equipment constituting the delivery cylinder, including the water box and pump. In addition, rubber piston rams typically have a short lifespan of about 3 to 6 months, which led to problems such as reduced work continuity due to maintenance and increased economic burden associated with replacement. However, as piston rams that come into contact with the inner wall of the cylinder have been used as a matter of course for a long time, it was by no means easy for an ordinary technician to change the piston ram itself or make any modifications to it. Furthermore, the piston ram generates a significant amount of heat due to repetitive operations inside the delivery cylinder under high pressure, which reduces durability and shortens its lifespan. Conventional urethane materials have a high coefficient of friction and are weak against heat, leading to a degradation of material performance during high-temperature and high-pressure operations, and the piston ram also had the same problem. Registered Patent Publication No. 568945, which aims to solve such problems, discloses a method for manufacturing a piston ram by: a coating process in which a solution mixed with nitrile rubber and toluene is applied to two sheets of cotton cloth with a thickness of 1.3 mm; a drying process in which the cotton cloth coated with the mixed solution in the coating process is dried for 11 to 13 hours; a consolidation molding process in which the dried cotton cloth is compressed by a roller and formed into a circular roll the size of the outer circumference of the piston seal, with the width being the same as the width of the upper piston seal; a die casting process in which the circular roll is inserted to be positioned at the outer circumference of the upper piston seal of the piston mold and the nitrile rubber solution is injected to perform molding casting; and a bonding process in which the manufactured piston is bonded to a ram cast by metal casting. However, this conventional technology involves molding using two sheets of cotton cloth and a roller, and has significant limitations in that the manufacturing process is complex and nitrile rubber is used to prevent a decrease in durability and wear resistance, so it ultimately failed to reach commercialization. In addition, Kor