Coating implements with material supply – Bifurcate pointed nib tool – Including reservoir and feeder
Reexamination Certificate
1998-11-20
2001-04-10
Recla, Henry J. (Department: 3751)
Coating implements with material supply
Bifurcate pointed nib tool
Including reservoir and feeder
C401S208000, C264S328100, C264S334000, C264S336000
Reexamination Certificate
active
06213666
ABSTRACT:
The invention relates to the simplified production of connectable sleeve-shaped elements which are produced by injection molding and may easily be secured and released (by screwing).
So far, sleeve-shaped plastics elements have been secured either by screw connections (thread joints) or by snap-in lockings (bayonet joints).
(a) Screw connections (thread joints) have the advantage to be easily releasable. Each consumer is familiar with their application. The substantial disadvantage of such connection is its relatively expensive production. For the production of parts with outer or inner threads by injection molding, tools are required, which, in addition to the pure translational opening movement of the injection molding machine, carry out further translational or rotary movements to be able to separate the thread contour of the injection molded part from its tool. Due to the greater number of elements and to the additional separating (detaching) movement, these tools are expensive and susceptible to failure. Moreover, due to the additional relative movement for removal, a longer cycle period in the production process is required, which period increases the production cost.
(b) Snap-in lockings have circumferential or segmental grooves, webs or ribs (“snap-in contours”) on rotationally symmetrical or polygonal sleeves. Usually, said snap-in lockings may be produced at a lower cost than screw connections, because no additional rotary removing movement is required to detach the snap-in contours from their mold. Partly, however, tools are used for the production of the parts, which tools—in addition to the translational opening movement of the injection molding machine—execute further translational movements to separate the snap-in contours from their mold and which, for this reason, are expensive. Snap-in connections have the principle disadvantage that the force serving for locking of the parts to be joined has to be overcome when disengaging them. Snap-in lockings always realize a compromise between best possible solidity and least possible loosening force: None of the two requirements may be optimized without deteriorating the other. In order to ensure reproducible holding and loosening forces, smaller tolerances than for screw connections have to be observed during production, which increases the production cost. When disengaging the snap-in locking, the snap-in geometry is partly deformed so that the holding force is reduced after several times of snapping-out and snapping-in—i. e. during use. Additionally, the functioning of said snap-in connections is not comprehensible for many consumers and therefore is not recognized to be a detachable connection, the possibility of multiple use of refillable instruments, particularly ball-point pens or ink writers, remaining unused.
The object of the invention is to provide a releasable securing of sleeve elements, said securing being easy to produce and easy to detach, but nevertheless having a high holding force when engaged.
This is achieved according to claim
1
.
The helical or spiral webs or ribs, segments or segmental parts are located on a conical envelope surface, the depth of its connecting contour (web or segment) having a defined ratio with respect to the angle of inclination of the envelope surface and being provided such that the connecting contour may be separated from its mold by slightly ductile or elastic deformation. This is achieved by providing every undercut (yielding a projection of the connecting contour) in such a way that the connecting contour formed from it—when being separated from the mold while moving in separation direction +z or −z—will not “snap into” an other undercut of the tool again.
Claim
3
,
4
,
7
.
Instead, it is elastically—or slightly plastically—lead past the next or the next but one form tool projection respectively, whereby claim
7
is to be read easier when regarding FIG.
8
and starting from a form tool projection which is further inside the thread structure.
Claim
5
.
According to the invention, the separation by screwing (time-consuming) or the separation by followers moving apart (expensive) is replaced by substantially only translational removal (in direction of the axis z), although the separated part is a part to be joined or engaged by turning.
Claim
6
.
All kinds of thread elements may be used. In order to further simplify the removal, said thread elements may have rounded edges or tops.
The connection (securing) provided by the invention comprises at least one of said thread elements, so that a simultaneously firm and easily releasable connection of the sleeves is achieved already by applying one turn. Despite the one turn, all thread turns (for example 10) are in simultaneous engagement and realize a connection which, on the one hand, is joined almost as fast as a bayonet joint (but with substantially larger turning angle) and, on the other hand, produces substantially the same holding forces, a usual cylindrical thread provides (but with substantially reduced turning angle).
Thus, the invention provides a quick-connecting thread of sleeves or sleeve elements for the production of writing instruments, additionally being inexpensive.
The sleeve elements being produced with the apparatus or with the process may be described as having a “conical thread section”. The thread root is provided on a surface inclined with respect to the separation axis, which surface being a hypothetical surface, as it has to be regarded as a connection cone of a helical or spiral thread root line. Said thread root line is slant and its inclination is adapted to the height of the thread webs such that a first thread web height has substantially the same radial dimension as the next but one (the one after the next) thread root, so that—in separation direction +z or −z—a thread web is only once plastically or elastically deformed at the form tool projection forming it and, thereafter, will not again be deformed permanently by the adjacent form tool projection, particularly may be lead past it without or with only slightly contacting it.
The continuous thread may also be designed in bayonet form. A number of circumferentially spaced thread elements—thread webs, thread segments or thread points—being located in axial direction one after the other on an inclined basic surface, so that the thread elements are located on continuously (negatively) offset radial levels in order to fulfill the aforementioned condition that a thread element provided by a form tool is stressed only once when removing it from its mold.
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Gantzert Erich
Lang Werner
Vial Siegbert
Duane Morris & Heckscher LLP
Merz & Krell GmbH & Co.
Nguyen Tuan
Recla Henry J.
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