Metal working – Method of mechanical manufacture – Valve or choke making
Reexamination Certificate
1999-10-26
2001-11-20
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Valve or choke making
C029S890120, C156S084000, C156S085000, C156S257000, C156S292000, C156S308200, C156S309900, C137S884000
Reexamination Certificate
active
06317977
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a fluid passage forming member by joining at least two passage members made of a thermoplastic synthetic resin such as a methacrylic resin.
DESCRIPTION OF THE RELATED ART
In a member for forming a fluid passage such as a manifold in which a plurality of solenoid valves for controlling supply and exhaust of compressed air are arranged and installed, a fluid passage forming member therefor is composed using a methacrylic resin or other light-transmitting synthetic resin in order to easily form a complicated passage or to make a fluid flowing through a passage formed therein visible. This is already known by, for example, the specification of U.S. Pat. No. 4,875,956, the specification of U.S. Pat. No. 4,999,069, or the specification of U.S. Pat. No. 5,041,181, etc. This type of fluid passage forming members is formed by joining at least two passage members having a plurality of junction surfaces that are joined to each other to form complicated fluid passages, and fluid passages formed by apertures or grooves in communication with each other between a pair of passage members are provided in junction surfaces of the foregoing passage members.
Such a fluid passage forming member is lighter than a solenoid valve manifold that has conventionally been used and exhibits stability against chemicals or the like, thus making it suitable for a passage of fluids related to medical treatment, chemicals, etc. However, if those fluids are to be passed through the fluid passage forming members, then the junction surfaces of the foregoing passage members that are joined with each other cannot be connected with an adhesive agent that includes an organic solvent when manufacturing the fluid passage forming members. This is because there is apprehension that an organic solvent may solve out into a fluid passing through the passage. For this reason, it is appropriate to form passage members by a thermoplastic synthetic resin that is stable against chemicals, and to heat and soften junction surfaces of the passage members so as to join the passage members at the junction surfaces by melting.
However, when heating and joining a pair of passage members formed of a thermoplastic synthetic resin, it is necessary to form fluid passages in advance by forming apertures or grooves, which communicate with each other, in the junction surfaces of the passage members and to heat and soften the passage members before pressing the junction surfaces into contact. At this time, the fluid passages formed beforehand shrink due to expansion of the synthetic resin constituting the passage members, or the fluid passages deform due to an external force applied to join the passage members formed of the softened synthetic resin. Hence, there are cases wherein the fluid passages cannot be formed in accordance with a design thereof, or the external configurations of the fluid passage forming members are deformed during the heating and joining process.
Thus, measures are required to prevent the shrinkage or deformation of fluid passages when heating and joining passage members. Furthermore, it is also necessary to rework the external configurations of the fluid passage forming members that have been made by joining the passage members for the purpose of installing or fixing solenoid valves to the mounting surfaces of the fluid passage forming members, connecting a fluid pipes thereto, etc.
SUMMARY OF THE INVENTION
The present invention has been made with a view toward solving the problem described above with a simple means, and it is basically an object thereof to provide a method that makes it possible to easily set a fluid passage to values close to design values, form an external configuration of a fluid passage forming member to a virtually predetermined configuration, and require easy machining if rework is necessary in manufacture of a fluid passage forming member formed of a thermoplastic synthetic resin.
Another object of the present invention is to provide a manufacturing method for a fluid passage forming member that permits heating at a relatively low temperature when joining passage members composed of a thermoplastic synthetic resin so as to minimize deformation during a joining process.
To these ends, according to the present invention, there is provided a method for manufacturing a fluid passage forming member by joining at least two passage members that are formed of a thermoplastic synthetic resin and have junction surfaces to be joined with each other. This method includes the steps of: forming fluid passages composed of apertures or grooves that are in communication with each other between a pair of passage members in the junction surfaces between the passage members, allowing for a shrinkage of the passages in advance so that the fluid passages having predetermined design sections may be formed by shrinkage of the fluid passages during a heating and joining process of the pair of passage members; and closely fitting the passage members in a forming mold with the passage members joined with each other at junction surfaces, sealing the mold while pressing the junction surfaces to be joined into contact, and heating and softening them to join them by melting at the junction surfaces thereby effecting connection at the junction surfaces of the passage members; wherein, in joining the passage members, deformation of the passage members in a direction orthogonal to the junction surfaces is restrained by an internal surface of the sealed forming mold, and a flow component of a material produced due to expansion of the passage members caused by heating of the passage members and contact pressing of the junction surfaces is moved along a surface parallel to the junction surfaces thereby to absorb it mainly by shrinkage of the fluid passages.
In the manufacturing method for the fluid passage forming members made of a synthetic resin, the close fitting of the passage members into the forming mold is effectively accomplished by pressing mold pieces into contact with the passage members in the forming mold at least in a direction in which the passage members joined with each other at the junction surfaces are deposited or in a direction parallel to the junction surfaces thereby to fix them. In this case, the contact pressing force between the junction surfaces of the passage members at the time of sealing the forming mold can be set by a tightening torque of a bolt for fixing an upper mold piece of the forming mold.
When forming the passage members by using a methacrylic resin, setting a heating temperature for joining the passage members at 110 to 130° C. is effective for preventing shrinkage or deformation of the fluid passages. Using a cast material as the methacrylic resin for forming the passage members is advantageous in that the directivity of shrinkage will be reduced.
Furthermore, in the manufacturing method for fluid passage forming members, use of a light transmitting thermoplastic synthetic resin for forming the passage members enables a liquid passing in the passages to be visible.
According to the manufacturing method for a fluid passage forming member made of a synthetic resin, apertures or grooves communicating with each other between a pair of passage members are formed with an allowance for an expected shrinkage which has been experimentally or empirically obtained in advance so that fluid passages having predetermined design sections may be formed by shrinkage of the fluid passages that takes place during a heating and joining process. Hence, even if the fluid passages deform because of expansion of a synthetic resin that occurs while heating and joining the passage members, or an external force applied to a softened synthetic resin for joining, or due to other reasons, the fluid passages can be set to values close to design values. When the fluid passages deform, since the fluid passages formed by the apertures or grooves are in communication with outside through gaps between mold pieces in a forming mold, there shoul
Iijima Katsumi
Wada Koji
Yoshida Yutaka
Compton Eric
Guss Paul A.
Hughes S. Thomas
SMC Kabushiki Kaisha
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