METHOD FOR THE FABRICATION OF A SCREW MEMBER FOR PLATE MEMBER FASTENER

Abstract

A method for making a screw member for plate member fastener is disclosed to include the step of preparing a metal element subject to a predetermined size and then processing the metal element through a cold extrusion forging operation to form a head at one end, a connection portion at an opposite end and a shank between the head and the connection portion, the step of processing the connection portion through a thread rolling operation to form threads around the periphery, the step of processing the threads to form a stop end edge at one side in proximity to the shank, and the step of finishing the final product.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a plate member fastener fabrication method and more particularly, to a method for making a screw member for plate member fastener that raises reliability of the use of the plate member fastener.

2. Description of the Related Art:

When fastening plate members together, a positioning screw formed of a knob, a ring and a screw nail is usually used. During installation, the screw nail and the ring are secured to the first plate member, and then the knob is rotated to drive the screw nail into the second plate member, and then a hand tool is used to fasten tight the screw nail, affixing the first and second plate members together. This plate member joining method can be used in a machine tool to join plate members together.

The power drive or speed-adjustment unit of a machine tool is provided inside the housing. To facilitate repair of the machine tool or adjustment of the output speed of the machine tool, a detachable plate member is usually provided at the housing of the power drive or speed-adjustment unit. Screw bolts are commonly used to fasten the movable plate member to the housing. When unfastening screw bolts to dismount a movable plate member from the housing, the associating lock nuts may fall from the screw bolts.

There is known a plate member fastener comprised of a cap, a screw member, a spring member and a locating base for joining two metal plate members together. After fixation of the locating base of the plate member fastener to a through hole on a first plate member, the screw member is threaded into a screw hole on a second plate member to secure the first plate member and the second plate member together. Because the locating base of the plate member fastener is kept secured to the first plate member after removal of the first plate member from the second plate member, the plate member fastener will not be missed by accident. According to this design, the screw member A, as shown in FIG. 9, has a head A1, a shank A2 perpendicularly extended from the center of the bottom side of the head A1 and a connection portion A3 axially extended from the bottom end of the shank A2 remote from the head A1. The connection portion A3 has an outer thread A31 spirally extending around the periphery. The outer thread A31 has a reduced end portion A311. During installation, the outer thread A31 of the connection portion A3 is threaded into the screw hole on the second metal plate member (not shown). When the reduced end portion A311 of the outer thread A31 reaches the inner thread of the screw hole of the second metal plate member, the first metal plate member and the second metal plate member are firmly secured together. If the operator continuously rotates the head A1 of the screw member A at this time, the reduced end portion A311 of the outer thread A31 will be threaded into the screw hole of the second metal plate member, causing the screw member A to be stuck in the screw hole of the second metal plate member. Therefore, when threading the screw member A into the screw hole of the second metal plate member, the rotary driving force must be properly controlled to avoid overthreading.

Further, the reduced end portion A311 of the outer thread A31 slopes in one direction. When the spring member is sleeved onto the screw member A and stopped between the reduced end portion A311 of the outer thread A31 and the bottom side of the head A1, the spring member may bias. When the screw member A, the cap and the locating base are assembled, the cap and the locating base may be not kept in perfect alignment. Small deviation of the component parts may increase the difficulty of the installation of the plate member fastener.

Accordingly, there is a strong need for plate member fastener that overcomes the aforementioned and other deleterious effects of the prior art plate member fastener.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a method for the fabrication of a screw member for plate member fastener, which facilitates mounting and dismounting of the plate member fastener, avoiding overthreading during installation.

A screw member fabrication method in accordance with the present invention includes the steps of (a) preparing a metal element subject to a predetermined size, and then processing the metal element through a cold extrusion forging operation to form a head at one end, a connection portion at an opposite end and a shank between said head and said connection portion, (b) processing the connection portion through a thread rolling operation to form threads around the periphery of the connection portion, (c) processing threads to form a stop end edge at one side in proximity to the shank, and (d) finishing the final product. When the screw member is used in a plate member fastener and threaded through a mounting through hole on a first metal plate member into a corresponding screw hole of a second metal plate member to secure the first metal plate member and the second metal plate member together, the stop end edge of the screw member avoids overthreading, preventing sticking of the screw member in the second metal plate member.

Further, the stop end edge is a flat edge extending in direction perpendicular to the axis of the screw member. When the screw member is used in a plate member fastener and a spring member is sleeved onto the screw member and stopped between the bottom side of the head and stop end edge of the screw member, the screw member will not be forced to bias and can be accurately threaded into the screw hole of the second metal plate member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the plate member fastener in accordance with the present invention.

FIG. 2 is a flow chart of the present invention showing the fabrication of a screw member for plate member fastener in accordance with the present invention.

FIG. 3 is a schematic sectional view, showing a metal element set in forging dies of a forging machine according to the present invention.

FIG. 4 is a schematic sectional view of the present invention, showing the thread rolling operation (I).

FIG. 5 is a schematic sectional view of the present invention, showing the thread rolling operation (II).

FIG. 6 is side view of a finished screw member according to the present invention.

FIG. 7 is an exploded view in sectional elevation of the present invention, showing the cap molded on the head of the screw member.

FIG. 8 is a sectional view of the present invention, showing the plate member fastener fastened to two metal plate members.

FIG. 9 is a side view of a screw member for plate member fastener according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 7, a plate member fastener in accordance with the present invention comprises a cap 1, a screw member 2, a barrel 3, and a spring member 4.

The cap 1 is a hollow member having a center opening 10 axially extending through the top and bottom sides for receiving the barrel 3, the screw member 2 and the spring member 4, a serrated inside retaining portion 11 arranged around the inside wall near the top side for retaining the engagement portion 211 of the screw member 2, and a grip 12 located on the periphery at the top side for gripping by hand.

The screw member 2 is a metal member having a head 21, an engagement portion 211 formed on the periphery of the head 21 for engagement with the serrated inside retaining portion 11 of the cap 1, a shank 22 perpendicularly extended from the center of the bottom wall of the head 21 and terminating in a connection tip 23, threads 231 spirally arranged around the periphery of the connection tip 23 and defining a stop end edge 2311 at a proximal side relative to the shank 22, and a tool groove 24 located on the top wall of the head 21. Further, the tool groove 24 can be a Phillipes groove, keystone groove, asterisk groove or hex groove.

The barrel 3 is a hollow cylindrical metal member having an inside accommodation space 30 extending through top and bottom sides thereof, a step 31 located on the inside around the inside accommodation space 30, a locating groove 32 extending around the inside wall inside the inside accommodation space 30 and abutted against the bottom side of the step 31, a bottom extension tube 33 axially forwardly extended from the bottom side of the barrel 3, and a bonding edge 331 defined on the bottom side of the barrel 3 around the bottom extension tube 33. Further, a retainer ring 34 is secured to the periphery of the shank 22 of the screw member 2 and positioned in the locating groove 32 inside the inside accommodation space 30.

The spring member 4 is sleeved onto the screw member 2, having a deformable coiled body 41 surrounding the shank 22 of the screw member 2 and two end portions 42 respective disposed at the two distal ends of the deformable coiled body 41.

Referring to FIGS. 2,3 4, 5 and 6, the screw member 2 is made of a metal element 5 that can be a steel, iron or stainless steel ingot.

The screw member 2 is made subject to the following steps:

• 100 Prepare a metal element 5 subject to a predetermined size.
• 101 Process the metal element 5 through a cold extrusion forging operation to form the desired head 21, shank 22 and connection portion 23.
• 102 Process the connection portion 23 through a thread rolling operation to form the desired threads 231.
• 103 Process the threads 231 to form the desired stop edge 2311 at one side in proximity to the shank 22.
• 104 Finish the desired screw member 2.

The metal element 5 is extruded into the desired length and width through a cold extrusion operation, and then processed through a cold forging process to form the desired head 21, shank 22 and connection portion 23. The cold extrusion forging operation is described hereinafter. After extrusion through a cold extrusion operation, the metal element 5 is put in between an upper die 61 and a bottom die 62 of a forging machine 6, and then forged to form the desired shank 22 and connection portion 23, and then a hammer forging die 63 is attached to one end of the metal element 5 outside the upper die 61 and the bottom die 62 and hammered to forge the respective end of the metal element 5 into the desired head 21. Thereafter, the shape-formed metal element 5 thus obtained is put in between the thread rolling faces 7111 and 7121 of the two flat thread rolling dies 711 and 712 of a first thread rolling die set 71 of a thread rolling machine 7, and then the two flat thread rolling dies 711 and 712 are reciprocated relative to each other to force the respective thread rolling faces 7111 and 7121 against the connection portion 23, thereby forming a semi-finished screw member 2 having the desired threads 231 around the periphery of the connection portion 23. Thereafter, the semi-finished screw member 2 thus obtained is put in between the thread rolling faces 7211 and 7221 of the two flat thread rolling dies 721 and 722 of a second thread rolling die set 72 of the thread rolling machine 7 wherein one flat thread rolling dies 721 has a top mounting groove 7213 located on the top wall 7210 thereof and an end edge-forming block 7212 affixed to the top mounting groove 7213 with a flat end edge-forming face 7214 thereof suspending in the thread rolling face 7211, and then the two flat thread rolling dies 721 and 722 of the second thread rolling die set 72 are reciprocated relative to each other to force the respective thread rolling faces 7211 and 7221 against the connection portion 23, causing the flat end edge-forming face 7214 to cut the end portion 2311 of the last thread 231 of the semi-finished screw member 2 so that a finished screw member 2 having the desired stop end edge 2311 at the end of the set of threads 231 in proximity to the shank 22 is thus obtained. When the screw member 2 is threaded into the screw hole 821 of a second metal plate member 82 during the use of the plate member fastener to secure a first metal plate member 81 to the second metal plate member 82, the stop end edge 2311 will be stopped against the inner threads 8211 to prohibit forward rotation, avoiding overthreading of the screw member 2 (see FIG. 8). Further, the flat end edge-forming face 7214 may be directly formed integral with the thread rolling face 7211 of the flat thread rolling die 721, or the end edge-forming block 7212 may be separately made and then inserted into the flat thread rolling die 721.

Referring to FIG. 7, the screw member 2 made subject to the aforesaid fabrication method is fastened to the cap 1, and then the spring member 4 is sleeved onto the screw member 2, and then the retainer ring 34 is fastened to the screw member 2 to secure the barrel 3 to the screw member 2 in the cap 1.

Further, the cap 1 can be directly molded on the head 21 of the screw member 2 with over-molding technology. After molding, the engagement portion 211 of the head 21 of the screw member 21 that can be formed of a series of barbs, teeth or protruding ribs is formed integral with the serrated inside retaining portion 11 of the cap 1. Thereafter, the spring member 4 is inserted into the center opening 10 of the cap 1 to sleeve the deformable coiled body 41, and then the barrel 3 is inserted into the center opening 10 of the cap 1 to have the screw member 2 and the spring member 4 be accommodated in the inside accommodation space 30 and the two end portions 42 of the spring member 4 be respectively stopped the bottom side of the head 21 of the screw member 2 and the step 31 of the barrel 3. Further, the retainer ring 34 is fastened to the periphery of the shank 22 of the screw member 2 and positioned in the locating groove 32 inside the barrel 3.

Referring to FIG. 8, during application of the present invention to fasten a set of metal plate members 8, an automatic installation machine is used to pick up the plate member fastener and then to insert the bottom extension tube 33 of the barrel 3 of the plate member fastener into the mounting through hole 811 of the first metal plate member 81 and to attach the bonding edge 331 of the barrel 3 to the solder paste 812 that was applied to the border area of the mounting through hole 811 of the first metal plate member 81, and then a reflow soldering process is applied to have the barrel 3 be bonded to the first metal plate 81.

After installation of the barrel 3 in the first metal plate member 81, attach the first metal plate member 81 to the second metal plate member 82 to aim the screw member 2 at the screw hole 821 of the second metal plate member 82, and then force the cap 1 downwards and rotate the cap 1 to drive the outer thread 231 of the screw member 2 into the screw hole 821 of the second metal plate member 82, and then attach a hand tool (for example, screwdriver) to the tool groove 24 of the screw member 2 and rotate the hand tool to tighten up the connection between the screw member 2 and the second metal plate member 82. Thus, the first metal plate member 81 and the second metal plate member 82 are firmly secured together by the plate member fastener. By means of the effect of the stop end edge 2311, the invention avoids overthreading of the screw member 2 and facilitates disconnection of the first metal plate member 81 from the second metal plate member 82.

Further, the stop end edge 2311 of the screw member 2 is a flat edge extending in direction perpendicular to the axis of the screw member 2. Thus, when the spring member 4 is received in the barrel 1 and the two end portions 42 are respectively stopped at the bottom side of the head 21 and stop end edge 2311 of the screw member 2, the screw member 2 will not be forced to bias and can be accurately threaded into the screw hole 821 of the second metal plate member 82.

While the present disclosure has been described with reference to one exemplary embodiment, it will be understood that the description of the exemplary embodiment is not a limitation of the invention.

Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.

Claims

1. A method for making a screw member for plate member fastener, the method comprising the steps of:

(a) Prepare a metal element subject to a predetermined size, and then process said metal element through a cold extrusion forging operation to form a head at one end, a connection portion at an opposite end and a shank between said head and said connection portion.

(b) Process said connection portion through a thread rolling operation to form threads around the periphery of said connection portion

(c) Process said threads to form a stop end edge at one side in proximity to said shank.

(d) Finish the final product.

2. The method of claim 1, wherein the step (a) is to put the prepared metal element put in between an upper die and a bottom die of a forging machine for enabling the metal element to be forged to form the desired shank and the desired connection portion, and then to attach a hammer forging die to one end of the metal element outside the upper die and the bottom die and to hammer the hammer forging die in forging the respective end of the metal element into the desired head.

3. The method of claim 1, wherein the step (b) is to put the shape-formed metal element thus obtained from the step (a) in between a thread rolling face of a first flat thread rolling die of a first thread rolling die set of a thread rolling machine and a thread rolling face of a second flat thread rolling die of said first thread rolling die set of said thread rolling machine, and then to reciprocate the first flat thread rolling die and second flat thread rolling die of said first thread rolling die set in reversed directions so as to form the desired threads around the periphery of the connection portion.

4. The method of claim 3, wherein the step (c) is to put the semi-finished screw member thus obtained from the step (b) in between a first flat thread rolling die of a second thread rolling die set of said thread rolling machine that has a thread rolling face at one side thereof and an end edge-forming face suspending in the thread rolling face and a second flat thread rolling die of said second thread rolling die set that has a thread rolling face at one side thereof, and then to reciprocate the first flat thread rolling die and second flat thread rolling die of said second thread rolling die set in reversed directions in forcing the respective thread rolling faces against the connection portion of the semi-finished screw member and causing said flat end edge-forming face to cut an end portion of one last thread of the threads of the semi-finished screw member into the desired stop end edge.