A screw structure includes a screw and a washer mounted on the screw. The bottom face of the screw head is provided with a plurality of pressing portions. Each of the pressing portions has a top provided with a first plane and a bottom provided with a second plane having an area smaller than that of the first plane. Each of the pressing portions is provided with a first inclined face and a first steep arcuate face. The first inclined face is directed toward a clockwise direction of the screw when the screw is screwed. The first steep arcuate face is directed toward the external thread. When the screw is screwed into an article, the pressing portions press the washer, and an outer diameter of the washer is expanded outward and forms an expansion.

A screw structure includes a screw and a washer mounted on the screw. The bottom face of the screw head is provided with a plurality of pressing portions. Each of the pressing portions has a top provided with a first plane and a bottom provided with a second plane having an area smaller than that of the first plane. Each of the pressing portions is provided with a first inclined face and a first steep arcuate face. The first inclined face is directed toward a clockwise direction of the screw when the screw is screwed. The first steep arcuate face is directed toward the external thread. When the screw is screwed into an article, the pressing portions press the washer, and an outer diameter of the washer is expanded outward and forms an expansion.

In its preferred embodiment, my invention presents a product and method whereby a series of containers can be held together along a longitudinal axis, a decorative covering can be held securely to a container, and an individual can easily and quickly change the appearance of the container by removing the attached covering and securely attaching another without need of an additional securing means included in either of the coverings. Changing the covering can be for reasons such as matching the look to a specific color scheme or to the surroundings it is in, to coordinate colors/theme of a specific holiday, or to align with a child's interests, such as a favorite sport they are involved in or a field of interest they follow.

In its preferred embodiment, my invention presents a product and method whereby a series of containers can be held together along a longitudinal axis, a decorative covering can be held securely to a container, and an individual can easily and quickly change the appearance of the container by removing the attached covering and securely attaching another without need of an additional securing means included in either of the coverings. Changing the covering can be for reasons such as matching the look to a specific color scheme or to the surroundings it is in, to coordinate colors/theme of a specific holiday, or to align with a child's interests, such as a favorite sport they are involved in or a field of interest they follow.

A formed body of Cu—Al—Mn-based shape-memory alloy may include a screw portion, wherein the screw portion is a form-rolled portion. A method for producing a formed body of Cu—Al—Mn-based shape-memory alloy may involve forming a screw portion having superelasticity by plastically working at least a portion of a material for the formed body with form-rolling in a state that a crystal structure is an A2-type structure and then, subjecting heat-treatment so as to convert the A2-type crystal structure into an L.sub.21-type crystal structure. The screw portion can be formed with good working property, and has excellent fatigue resistance and breaking resistance.

A formed body of Cu—Al—Mn-based shape-memory alloy may include a screw portion, wherein the screw portion is a form-rolled portion. A method for producing a formed body of Cu—Al—Mn-based shape-memory alloy may involve forming a screw portion having superelasticity by plastically working at least a portion of a material for the formed body with form-rolling in a state that a crystal structure is an A2-type structure and then, subjecting heat-treatment so as to convert the A2-type crystal structure into an L.sub.21-type crystal structure. The screw portion can be formed with good working property, and has excellent fatigue resistance and breaking resistance.

A ceiling fan motor housing includes a bottom cover member, a hollow housing member, and a plurality of screws. The bottom cover member is formed with a plurality of threaded holes. The housing member is formed with a plurality of L-shaped positioning members extending from a bottom end thereof. Each of the positioning members has a vertical portion which is connected to the bottom end of the housing member and a horizontal portion which extends inwardly from a bottom end of the vertical portion, supports the bottom cover member, and is formed with a positioning hole. The screws respectively extend through the positioning holes of the positioning members to respectively engage the threaded holes of the bottom cover member.

A screw assembly includes a screw and a washer mounted on the screw. The screw includes a screw head, a rotation portion formed on a top of the screw head, and an external thread formed on a bottom of the screw head. The bottom of the screw head is provided with at least one projection and at least one recessed portion. When the external thread is screwed into an article, the washer is compressed between the screw head and the article. The at least one projection and the at least one recessed portion press the washer, and the washer is expanded outward and forms an expansion. The at least one projection and the at least one recessed portion enhance an airtight effect of the washer.

A screw assembly includes a screw and a washer mounted on the screw. The screw includes a screw head, a rotation portion formed on a top of the screw head, and an external thread formed on a bottom of the screw head. The bottom of the screw head is provided with at least one projection and at least one recessed portion. When the external thread is screwed into an article, the washer is compressed between the screw head and the article. The at least one projection and the at least one recessed portion press the washer, and the washer is expanded outward and forms an expansion. The at least one projection and the at least one recessed portion enhance an airtight effect of the washer.

An electric connector comprises a wall surrounding a receptacle that receives a strand of an electric wire and having a threaded hole extending through the wall and opening into the receptacle, and a fastener bolt screwed into the threaded hole and clamping the electric wire. The fastener bolt includes a bolt part having a head section, a thread section and a shearing section connecting the head section and the thread section. The fastener bolt further includes a nut part screwed onto the thread section. The shearing section is adapted to break if a predetermined fastening torque is exceeded. The thread section is hollow and has a predetermined tensile breaking strength.