U.S. patent application number 09/828750 was filed with the patent office on 2001-11-01 for production of releasably secured sleeve elements.
Invention is credited to Gantzert, Erich, Lang, Werner, Vial, Siegbert.
Application Number | 20010036382 09/828750 |
Document ID | / |
Family ID | 8219295 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010036382 |
Kind Code |
A1 |
Lang, Werner ; et
al. |
November 1, 2001 |
Production of releasably secured sleeve elements
Abstract
A conical thread structure .alpha..sub.1, .alpha..sub.2, t is
provided to simplify the removal of threads in plastics sleeve
elements 1,2,3,4 and to decrease production cost. The radial
distance of the thread elements 50,60,51,61 of said thread
structure and of the corresponding form tools, which elements being
adjacent in translational z or -z direction, are dimensioned such
that, when removed E0,E1,E2 of F0,F1 from the mold each thread
element "snaps out" only once and does not snap into a second
time.
Inventors: |
Lang, Werner; (Weinheim,
DE) ; Vial, Siegbert; (Rossdorf, DE) ;
Gantzert, Erich; (Gross-Bieberau, DE) |
Correspondence
Address: |
STEPHAN P. GRIBOK
DUANE MORRIS & HECKSCHER, LLP
ONE LIBERTY PLACE
PHILADELPHIA
PA
19103
US
|
Family ID: |
8219295 |
Appl. No.: |
09/828750 |
Filed: |
April 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09828750 |
Apr 9, 2001 |
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08973450 |
Nov 20, 1998 |
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6213666 |
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Current U.S.
Class: |
401/1 |
Current CPC
Class: |
B43K 7/005 20130101;
B43K 15/00 20130101; B29L 2031/7252 20130101; B29C 33/444 20130101;
B43K 5/005 20130101; B43K 21/006 20130101; B29C 45/00 20130101;
B29C 37/0021 20130101; B29C 37/0014 20130101 |
Class at
Publication: |
401/1 |
International
Class: |
B43M 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 24, 1995 |
DE |
95 10 8034.0 |
May 23, 1996 |
DE |
PCT/DE96/00903 |
Claims
1. Process for production of sleeve elements (1,2) made of plastics
material, which elements are easily removable from their mold
(21,12) and releasable secured (by screwing)--particularly
connecting the rear shaft (2) and the front gripping sleeve (1) or
of the rear head piece or cap (3) and the front shaft (4) of a
writing instrument--, wherein (a) a series of thread webs, thread
segments or thread points (1,1a', 1a",1a*) periodical in axial
direction (z,100), is provided on a slightly conical thread basis
of one of said sleeves (1); (b) a series of webs or segments (1a,
1a', 1") periodical in axial direction (z,100), is provided on a
slightly counter-conical basic surface of the other one (2) of said
sleeves (2).
2. Process according to claim 1, wherein the angle of inclination
(.alpha.2) of one or both of said conical and counter-conical basic
surface is adapted to the radial height (t) of said segments, webs
or points (1a,1a',1a",1a*) such that when removed (E1,E2) from the
injection mold (12,21) with substantially translational removal
movement, none of them snaps into a tool contour again, a slight
plastic or ductile deformation not being regarded as "snapping
into".
3. Process according to one of the aforementioned claims, wherein
the removal from the mold (20,21) in direction of the axis (z) is
effected by elastic (radial) deformation of said thread elements
(webs, segments, points).
4. Process according to claim 1 or 2, wherein the removal from the
mold (21,21) in direction of the axis (z,100) is effected by
plastic or ductile radial deformation with slight modification of
said thread elements (webs, segments or points).
5. Process according to one of the aforementioned claims, wherein
the removal of said thread elements from the mold is effected in
only axial direction (z,100), particularly without or without
substantial radial follower motion or screw motion.
6. Process according to one of the aforementioned claims, wherein
said thread webs, segments or points (thread elements) have rounded
(R) edges.
7. Form tool for carrying out the process according to one of the
aforementioned claims, having (a) a negative contour (12a,21a) of a
thread structure (webs, segments, naps or points) of a female or
male thread (1a,2a) of a sleeve (1,2); (b) a projection (X1) in the
form tool (12,21) for forming a recess (50,60,I1) in the thread
structure (1a,2a) of the sleeve, said projection radially not
protruding or protruding only slightly with respect to the next
form tool recess (X4) adjacent at least at a distance (.sigma.) of
the thread pitch contrary to the removing direction (z,100); or the
next but one form tool recess (X4) adjacent in axial direction
(z,100) for the molding of the next but one (the next one after the
next) or the following elevation (51b,61b,I4) respectively of the
thread structure (1a,2a) of the sleeve; or (c) a first projection
(X1;X4) in the form tool (12,21) for forming a first recess
(50,60,I1 ;A4) in the thread structure of the sleeve (1a,2a), said
first projection (X1;X4) having a radially smaller dimension with
respect to a second projection (X3;X2) in the same form tool
(12,21), said second projection (X3;X2) being adjacent in a
direction opposite to the direction of removal for forming a second
recess (50a,60a,I3;A2) adjacent to the first recess (50,60,I1;A4)
in the same thread structure of the sleeve (1a,2a).
8. Form tool according to claim 7, wherein a connecting line of all
form tool projections constitutes a (straight) line which is
inclined or slant (.alpha.2) with respect to said axis (100) or
said removal direction (z) of said form tool (12,21) or said sleeve
(1,2).
9. Form tool according to claim 8 or 7, wherein a connecting line
of all form tool recesses constitutes a second line which is
inclined (.alpha.2)--particularly by the same angle (.alpha..sub.2)
as the aforementioned first line--with regard to said axis (100) or
said removal direction (z) of said form tool (21,12) or said sleeve
member (1,2).
10. Form tool according to one of the claims 7 to 9, wherein the
second form tool recess (X4) located prior to a form tool
projection (X1)--viewed in mold removal direction
(z)--substantially has the same radial dimension as said form tool
projection (X1), so that (a) said form tool (21) is--viewed in
direction (z) of the removal movement (F1) of the external sleeve
--slightly conically reduced in the thread molding section (21a)
for the molding of a conical (inner) thread (2a); or (b) the thread
molding section (1a) of said form tool (12) has a slightly conical
expansion--viewed in direction (z) of the removal movement (E2) of
said sleeve element (1) with outer thread--for the molding of a
conical (outer) thread (12a).
11. Sleeve element with conical quick-connecting thread section
(1a,2a) for a writing instrument, such as a ball-point pen, pencil
with retractable point or ink writer, produced according to one of
the aforementioned process claims or with an apparatus according to
one of the aforementioned apparatus claims, wherein said sleeve
element (2,4,HI,HA) is provided with several, particularly more
than two, bayonet-type thread elements (webs, segments or points)
being circumferentially spaced with respect to each other and--in
axial direction (z,100)--located one after the other, but on
continuously offset radial levels on a conical basic surface.
12. Sleeve element with conical quick-connecting thread section
(1a,2a) on a conical thread basic surface produced according to one
of the aforementioned process claims or with an apparatus according
to one of the aforementioned apparatus claims, wherein said sleeve
element (2,4,HI,HA) is provided with a helical or
spiral--continuous--thread web (1a,2a) being radially dimensioned
such that--viewed in section--a first thread web height (I4,A1) has
substantially the same radial dimension as the next but one (the
next one after the next) thread root (I1,A4) in removal direction
(+z,-z, FIG. 8).
Description
[0001] 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).
[0002] So far, sleeve-shaped plastics elements have been secured
either by screw connections (thread joints) or by snap-in lockings
(bayonet joints).
[0003] (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.
[0004] (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.
[0005] 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.
[0006] This is achieved according to claim 1, 7 or claim 11 or
12.
[0007] 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 1,7,12).
[0008] Claim 3, 4, 7.
[0009] 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.
[0010] Claim 5.
[0011] 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.
[0012] Claim 6.
[0013] All kinds of thread elements may be used. In order to
further simplify the removal, said thread elements may have rounded
edges or tops.
[0014] The connection (securing) provided by the invention
comprises at least one of said thread elements, so that a
simultaneously firm and easy 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).
[0015] Thus, the invention provides a quick-connecting thread of
sleeves or sleeve elements (claim 11, claim 12) for the production
of writing instruments, additionally being inexpensive.
[0016] The sleeve elements being produced with the apparatus (claim
7) or with the process (claim 1) may be described as having a
"conical thread section" (claim 12, claim 11). 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 one
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 (claim 12).
[0017] The continuous thread (claim 12) may be also designed in
bayonet form (claim 11). 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.
[0018] The invention is described in detail by schematic drawings
on the basis of several embodiments.
[0019] FIGS. 1a-1d are embodiments of thread elements 1a, 1a', 1a",
1a* on a gripping sleeve of a ball-point pen, which thread elements
are connectable by screwing in a turning movement.
[0020] FIG. 2a shows the conical outer thread contour 1a on another
gripping sleeve 1, with a broken-out section and diameters d,D
(max/min) of the thread root and the thread web;
[0021] FIG. 2d shows the same contour 3a on a rear end piece 3 of a
writing instrument--which end piece may be secured by turning in,
in a countersunk or concealed manner as well.
[0022] FIGS. 2b,2c are sectional views of embodiments of thread or
rib profiles of FIGS. 2a,2d.
[0023] FIG. 3a, shows the conical inner thread contour 2a on a
cylindrical gripping sleeve or shaft 2;
[0024] FIG. 3d shows the same contour 4a on a conically ending
front sleeve element 4 being securable at its rear end by head
(end) piece 3.
[0025] FIGS. 3b,3d are sectional views of embodiments of thread
profiles of FIGS. 3a,3d.
[0026] FIG. 4a-4d are different instantaneous views showing in
longitudinal section the separation of an outer thread 1 a from its
mold according to the invention. The relative movements are
represented by E0,E1,E2. FIGS. 5a-5c are different instantaneous
views showing in longitudinal section the separation of an inner
thread 2a from its mold. The relative movements are represented by
F0 and F1. FIGS. 6a-6c are different instantaneous views in
longitudinal section showing an inner thread 2a, secured in a
turning manner to an outer thread 1a both being provided on sleeve
elements 1,2 (securing of sleeves according to FIGS. 2a,3a). FIGS.
7a-7c are different instantaneous views of sleeve elements 3,4 in
longitudinal section showing an inner thread 4a being connected to
an outer thread 3a according to the invention (connection of sleeve
elements according to FIGS. 2d,3d).
[0027] FIG. 8 is a schematic (simultaneous) sectional view
illustrating the thread structure of an inner thread 11,12,13,14 on
a sleeve HI and the thread-forming tool 12a with its outer surface
as well as the thread contour of an outer thread A1,A2,A3,A4 of a
sleeve HA with its thread-forming tool contour 21 a which is
located on the inner surface of the molding line/surface 12a/21a.
Despite being illustrated as a line, said molding surface 12a is a
representation of said tool 12a according to FIG. 4d as well as of
said tool 21 a according to FIG. 5c.
[0028] The connection 1/2 or 3/4 (see FIGS. 6,7) may be produced at
a low cost with injection molding tools of simple structure. The
elements may rapidly and easily be connected by screwing after
having been pushed together in axial direction beforehand.
[0029] The securing (connecting) system comprises a helical or
spiral rib or web (FIG. 1a)--being provided on a cylindrical or
conical outer and/or inner contour. Said rib or web may as well be
discontinuous and consist of segments (FIG. 1b). Said segments may
as well be only partly helical (FIG. 1c). The contour and height of
said thread elements is designed such that they are separable from
their mold by simple injection molding tools. The molding parts of
the tool exclusively move in z direction, the opening direction of
the injection molding machine (FIG. 4 and FIG. 5 show the
contour-giving or molding sections of two tools for the production
of the two sleeve connection elements).
[0030] The helically or spirally extending naps, points 1a*,
segments 1a' or segmental elements 1a" may as well be located on
only one of the two sleeve elements to be joined, if not helically
shaped contours 1* engaging them are provided on the other
connection element (FIG. 1d).
[0031] Said helically disposed naps, points, segments or segmental
elements are located on a conical basic surface, the depth of the
connection contour (web or segment) of which has a defined relation
with respect to the angle of inclination of the basic surface and
is provided such that the connection contour may be separated from
its mold by elastic deformation. This is achieved by only once
translationally separating the connection contour past each
undercut.
[0032] Separation from the mold is effected only once, if the
following relations are applied (FIG. 2 and FIG. 3):
[0033] .epsilon..sub.m[%] possible material expansion of the
plastics material of the sleeves.
[0034] D[mm] largest diameter of the conical sleeve 1a, 2a.
[0035] d[mm] smallest diameter of the conical sleeve 1a, 2a.
[0036] t[mm] depth of the web.
[0037] .sigma.[mm] helical pitch or web distance.
[0038] .alpha..sub.1[.degree.] removal angle.
[0039] .alpha..sub.2[.degree.] inclination angle in the sleeve 1a,
2a.
[0040] 1. t=d.multidot..epsilon..sub.m /200 d is given by the
constructive dimensions,
[0041] 2. .alpha.2'=arcsin (t/.sigma.) .sigma. has to be selected
according to functional requirements. .alpha.2>.alpha.2'
[0042] FIG. 2a shows the conical outer contour, FIGS. 2b and 2c are
sectional views of web profiles. FIG. 3a shows the conical inner
contour, FIGS. 3b and 3c are sectional views of web profiles.
[0043] The possibly material expansion em is dependent on the
plastics material, the separation angle .alpha..sub.1<90.degree.
and the separation radii R. The possible web depth t results from
.epsilon..sub.m and d according to equation 1. A dimensioning angle
.alpha..sub.2' is obtained according to equation 2 from t and the
desired pitch or the desired web distance .sigma..
[0044] The inclination angle .alpha..sub.2 of sleeve element 1a/3a
or 2a/4a of sleeve 1 or 2 or 3 or 4 should in ideal circumstances
be larger than or equal .alpha..sub.2'. If it is selected to be
larger, the turning or screwing connection (after initially pushing
one sleeve element axially into the other) requires a smaller
turning angle for securing; if it is selected to be smaller,
separation of the sleeve from its mold approaches repeated snapping
in and out. Thus, the dimensioning angle .alpha..sub.2' may be
interpreted as "angle limit".
[0045] If a non-elastic plastics material is selected,
.alpha..sub.1 is more acute (FIG. 2c) than if a more elastic
plastics material is used (FIG. 2b).
[0046] The forming contour on the form tool is dimensioned such
that a thread element (web 51/61 with adjacent groove or recess
50/60) is radically offset with respect to the thread element
adjacent at a distance .sigma. (thread pitch). Usual threads--which
are difficult to detach--do not have a radically differing
dimension. The conical thread section 1a,2a,3a,4a results from the
radically differing dimension recurring periodically throughout the
length of the thread. FIGS. 2a, 2c and 3b, 3c show a thread element
for an outer and an inner thread respectively. The thread elements
50/51 are disposed one after the other in axial direction or in
separation direction z respectively; next to them 50a, 51a are
located, followed by 50b, 51b, and, in the same structure, the
inner thread according to FIG. 3b is arranged with its thread
elements 60,61, followed by the next thread element 61a,60a being
adjacent thereto contrary to the separation direction z, and the
next but one thread element 60b,61b. All said thread elements have
further dimensions t, .sigma. and the two specification angles
.alpha..sub.1,.alpha..sub.2, .alpha..sub.2 defining the cone for
the basic surface of the thread and the inclined shape of the
thread.
[0047] The dimensions for these values are defined by the above
mentioned equations (1) and (2) and the separation angle
.alpha..sub.1 is substantially dependent on the plastics material
used. If a simplified removal is desired for harder plastics
materials, the sharp transitions and edges in the thread elements
50/51 and 60/61 according to FIGS. 2b and 3b may be rounded, for
which purpose a number of radii R are indicated in FIG. 2c and
3c.
[0048] The separation movement of an outer thread is described in
FIG. 4 by instantaneous views. The above described thread section
is molded by a thread-forming sleeve 12, which is located closely
adjacent to and concentrical with a mold 10 to constitute the outer
diameter of a mold cavity 10a. A mandrel 11 is introduced into said
cavity, the outer diameter of which mandrel is smaller by the
thickness of the desired sleeve 1 than the above mentioned inner
diameter of said mold 10 and said thread sleeve 12. At its face
end, said mandrel 11 has a substantially cylindrical ram, forming
the front outlet opening of the conically ending gripping sleeve
1--the form part. An ejector 13 is illustrated engaging said
thread-forming sleeve 12 and defining the rear end of the thread
section 1a to be molded in the thread-forming section 12a of said
thread-forming sleeve 12. Said ejector is axially movable and
closely adjacent to and slidable on said mandrel 11.
[0049] Liquid plastics material is injected into the mold cavity of
the arrangement illustrated in FIG. 4a.
[0050] After cooling, said first mold 10 is moved away from said
gripping sleeve 1 by the separating movement E0 in +z direction
according to FIG. 4b. Said translational movement does not cause
any problems. Thereafter, said mandrel 11 is retracted in
separating direction E1 according to FIG. 4c, said ejector 13
maintaining its position unchanged with respect to said
thread-forming sleeve 12.
[0051] Finally, according to FIG. 4d, the finished gripping part 1
with its conical thread section 1a is ejected in forward direction
by said ejector 13 with its removal direction E2, without any
follower movement in a direction perpendicular to said ejection
movement E2, which is a movement in +z direction, and without any
turning movement being required, neither for said thread-forming
part 12 nor said gripping sleeve 1.
[0052] Due to the conical shape of said thread 1 a, having at its
right (inner) end a larger radius than at its left (outer) end,
according to FIG. 2a, the separating movement of said thread may be
effected in a short time without damaging the thread turns and
thread webs.
[0053] The production process for an inner thread according to
FIGS. 5a and 5c functions in a similar manner. A mold 20 with a
mold cavity is provided as well which mold is closely arranged to
an ejector block 22 at its face end according to FIG. 5a, thus
defining the outer contour of said sleeve element 2 to be formed. A
ram 21 is inserted into the mold cavity to determine a hollow space
for the injection molding of said sleeve 2 between its outer
surface and the inner surface of said mold 20. A thread-forming
section 21a is provided on said ram 21, which section, in the
inserted position, is located directly behind said ejector 22. If
assembled in the described manner, the arrangement is ready to be
filled with plastics material in an injection molding process as
illustrated in FIG. 5a.
[0054] In the mold separating process, said mold 20, which does not
cause any difficulties, is axially pushed off by movement FO, being
a movement in +z direction.
[0055] Thereafter, said substantially solidified sleeve element 2
may be pushed off axially, also in +z direction, from said conical
thread-forming section 21a, said block-shaped ejector 22 effecting
an axial movement in F1 direction substantially corresponding to
the length of said ram 21. It is also possible to retract said
mandrel 21 in the same way, said block 22 remaining in its resting
position, so that the separation of said sleeve 2 is obtained by a
movement in -F1 direction.
[0056] No radial movement is required to remove said sleeve element
2 from the mold, no turning or rotating movement of said sleeve 2
or of said mandrel 21 is applied, so that the removal may be
effected safely, gently and rapidly.
[0057] The assembly of a gripping part 1 and a shaft part 2 is
described in three steps in FIGS. 6. FIG. 6a shows the partly axial
introducing of the conical outer thread 1a into the conical
counter-thread (inner thread) 2a up to a distance corresponding to
said thread pitch .sigma., when .alpha..sub.2, =.alpha..sub.2 being
selected. Thereafter,
[0058] in FIG. 6b, a turning or screwing movement is applied, which
may be substantially one rotation, to bring all thread sections
simultaneously into releasable engagement according to FIG. 6c. The
assembly of sleeve parts 3 and 4 is effected in a similar manner:
axially inserting up to a short remaining distance being .sigma.,
when .alpha..sub.2,=.alpha..sub.2 being selected, and subsequent
turning for reasonable but firm securing. FIG. 7 may also be
regarded such that the head or end piece 3 is screwed upon the free
end of said sleeve 2 according to FIG. 6, so that a ball-point pen
consists of three elements of sleeve-shaped nature, every two of
which at a time are brought into engagement by the connection of
conical threads. Said short remaining distance .sigma. varies
depending on the modification of .alpha..sub.2 . It becomes smaller
when .alpha..sub.2 becomes larger than .alpha..sub.2,.'
[0059] FIG. 8 illustrates a conical thread, the thread forming part
(the tool having a thread-forming section for an outer thread or an
inner thread) being shown only by one single line 12a or 21a in the
middle of FIG. 8. (a) Above said line, a part of a sleeve HI with
an inner thread is shown. (b) Below said line 21a, a sleeve HA with
an outer thread is shown.
[0060] Said sleeve Hi with inner thread corresponds to FIGS. 5, the
removal movement F1 being correspondingly shown also in FIG. 8.
Said sleeve HA with outer thread corresponds to FIGS. 4, FIG. 8
also showing the removal movement E2 corresponding to FIGS. 4.
[0061] FIG. 8 illustrates the relations between a particular form
tool projection (part of the tool which forms a recess in the inner
or outer thread) and adjacent to said projection a form tool recess
or undercut, which is responsible for the corresponding adjacent
projection on the same above mentioned thread.
[0062] "X" designates all tool projections and recesses, "A" all
outer thread projections and recesses and "I" all inner thread
projections and recesses.
[0063] (a) For example, a form tool projection X1 produces a
corresponding inner thread recess l1 in sleeve HI. Projection 12,
which is adjacent in -z direction, is formed by the adjacent form
tool recess X2 and the form tool projection X3, which is further
adjacent to said form tool recess X2, forms the corresponding inner
thread recess 13. A relation for the conical thread may be
established between the next (following) inner thread projection I4
(resulting from the corresponding form tool recess X4) and the
aforementioned form tool projection X1. In case the radial
dimension of I4 is the same as that of X1, HI may be (easily)
separated in removal direction F1 without I4 upon separation
contacting a further tool projection except for the tool projection
X3 forming I4. Instead, it passes all tool projections X1 and all
tool projections located before (in removal direction +z) without
contacting them.
[0064] The corresponding line L2 connecting all form tool
projections X1,X3, . . . illustrates the angle .alpha..sub.2 as
described above.
[0065] (b) Similar to the above description for sleeve HI, the same
removal movement E2 and the same relation may be established
between a form tool recess X1 and the corresponding thread web Al
and a form tool projection X4 being spaced by more than one thread
pitch .alpha.in direction E2. The connection of all form tool
projections are located on a conical surface L1 marked by a
dot-dash line.
[0066] A conical thread structure .alpha..sub.1,.alpha..sub.2 , t
is provided to simplify the separation of threads in plastics
sleeve elements 1,2,3,4 and to decrease production cost. The radial
distance of the thread elements 50,60,51,61 of said thread
structure and of the corresponding form tools, which elements being
adjacent in translational z or -z direction, are dimensioned such
that, when removed in direction E0,E1,E2 or F0,F1 from the mold
each thread element "snaps out" only once and does not snap into a
second time.
* * * * *