U.S. patent application number 10/779771 was filed with the patent office on 2004-11-04 for disk-shaped object of synthetic thermoplastic material, and method for producing same.
This patent application is currently assigned to Newfrey LLC. Invention is credited to Schaty, Harald.
Application Number | 20040219325 10/779771 |
Document ID | / |
Family ID | 33030893 |
Filed Date | 2004-11-04 |
United States Patent
Application |
20040219325 |
Kind Code |
A1 |
Schaty, Harald |
November 4, 2004 |
Disk-shaped object of synthetic thermoplastic material, and method
for producing same
Abstract
A disk-shaped object of synthetic thermoplastic material has
contact surfaces on opposite sides that possess a rough texture. In
a method for production of the disk-shaped object, synthetic
material is injected under pressure in a plasticized state into a
cooled molding tool and removed therefrom after a cooling phase,
the molding tool having correspondingly rough molding surfaces to
form the rough contact surfaces of the object.
Inventors: |
Schaty, Harald; (Wetzlar,
DE) |
Correspondence
Address: |
MILES & STOCKBRIDGE PC
1751 PINNACLE DRIVE
SUITE 500
MCLEAN
VA
22102-3833
US
|
Assignee: |
Newfrey LLC
|
Family ID: |
33030893 |
Appl. No.: |
10/779771 |
Filed: |
February 18, 2004 |
Current U.S.
Class: |
428/64.1 ;
428/141 |
Current CPC
Class: |
Y10T 428/21 20150115;
C08L 77/00 20130101; C09J 5/06 20130101; C09J 2477/00 20130101;
Y10T 428/24008 20150115; B29C 45/372 20130101; Y10T 24/33 20150115;
Y10T 24/309 20150115; B29C 45/263 20130101; C09J 7/10 20180101;
Y10T 24/42 20150115; Y10T 428/24355 20150115 |
Class at
Publication: |
428/064.1 ;
428/141 |
International
Class: |
B32B 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2003 |
DE |
10307108.3 |
Jan 29, 2004 |
DE |
102004004701.4 |
Claims
What is claimed is:
1. Disk-shaped object of synthetic thermoplastic material, such as
thermoplastic adhesive, for use as an intermediate between parts,
has contact surfaces on opposite sides of the object that are
rough, wherein their averaged roughness depth R.sub.x lies in a
range from 40 to 100.mu..
2. Object according to claim 1, wherein the averaged roughness
depth R.sub.z of the contact surfaces lies in the range from 55 to
70.mu..
3. Object according to claim 1, wherein the arithmetic mean
rugosity R.sub.a lies in a range from 6 to 25.mu..
4. Object according to claim 2, wherein the arithmetic mean
rugosity R.sub.a lies in a range from 10 to 15.mu..
5. Method of producing a disk-shaped object according to any one of
the preceding claims, wherein the synthetic material is injected
under pressure in a plasticized state into a cooled molding tool
and removed therefrom after a cooling phase, and wherein molding
surfaces of the molding tool form the contact surfaces of the
object and are textured with a roughness depth equivalent to that
of the contact surfaces.
6. Method according to claim 5, wherein opening of the molding tool
takes place prior to the complete cooling of a disk-shaped object
contained therein.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of German Patent
Application 10307108.3 filed 19 Feb. 2003 and German Patent
Application 102004004701.4 filed 29 Jan. 2004, both of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a disk-shaped object of synthetic
thermoplastic material and to a method for producing the same.
[0003] Disk-shaped objects are employed, for example, as an
intermediate between structural parts to seal them off from one
another and/or connect them adhesively to one another. Examples of
such applications are disclosed in GB 2,067,253 A and EP 0,504,957
A2. In these applications, a disk-shaped object is arranged between
parts to be connected and then brought into a flowable state by
heating, so that the disk-shaped object will adhesively connect the
two parts to one another and possibly penetrate gaps between the
parts to seal them tight.
[0004] In the production and assembly of disk-shaped objects of the
kind specified, various problems have arisen. The objects have been
difficult to remove from the recess of a molding tool. Objects of
annular shape especially have also exhibited a marked ill-defined
warping and shrinking behavior, so that prescribed dimensions have
failed to be reliably attained. Furthermore, individual objects
when transported in bulk have tended to stick together, interfering
considerably with individual use, especially in automatic assembly.
Experiments with a suitable liquid as parting agent, to prevent the
individual objects from sticking together, have failed to yield
satisfactory results.
BRIEF DESCRIPTION OF THE INVENTION
[0005] Accordingly, an object of the invention is so to configure
disk-shaped objects of the kind specified so that they are easily
isolated and assembled.
[0006] Another object of the invention is to improve a process of
production of such objects, to alleviate unmolding problems and to
prevent warping and shrinking of the objects.
[0007] According to the invention, contact surfaces provided on
opposite sides of a disk-shaped object of synthetic thermoplastic
material are made rough. Surprisingly, it has been found that with
a rough condition of the contact surfaces, adjacent disk-shaped
objects no longer have the tendency to stick together, but are
easily separated and isolated from each other. No additional
parting agents are required. Mechanical means of automatically
isolating and assembling the objects formed according to the
invention can therefore be operated without trouble.
[0008] By a process according to the invention, suitable roughness
of the contact surfaces is generated in the forming of the objects.
More particularly, molding surfaces of a molding tool forming the
contact surfaces are provided with a roughness matching the desired
contact surfaces of the objects. Due to the roughness, a
disk-shaped object is better secured in the tool, and
disadvantageous shrinking and warping effects are avoided. Further,
it has been found that by opening the molding tool prior to
complete cooling, slight residual shrinkage, still to occur, favors
the parting of object and tool, considerably facilitating the
unmolding and ejection of the object from the molding tool.
Deformations of the object, caused by the unmolding operation, are
avoided in this way.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be further described in conjunction with
the accompanying drawings, which illustrate preferred (best mode)
embodiments, and wherein:
[0010] FIG. 1 shows a perspective representation of a disk-shaped
object according to the invention;
[0011] FIG. 2 shows a cross-section of a molding tool for producing
an object according to the invention; and
[0012] FIG. 3 shows the use of a disk-shaped object according to
the invention for tight connection of two structural parts.
DETAILED DESCRIPTION OF THE INVENTION
[0013] In one embodiment according to the invention, an object 1
shown in FIG. 1 is in the form of a circular disk having two
parallel circular faces, forming contact surfaces 2, 3. The disk
has a diameter of about 15 mm and a thickness of about 1 mm, for
example. In the center of the object 1, there is a square
through-hole 4. The diagonal dimension of the hole 4 is smaller
than the outside diameter of the object 1, of course. A disk-shaped
object in accordance with the invention may have a non-circular
contour and may have a non-square hole.
[0014] The object 1 is made of a thermoplastic adhesive that can be
brought into a flowable state by heating. At a temperature of about
20.degree. C., for example, the material of the object 1 is solid,
not completely rigid but elastically deformable. Such an adhesive
of polyamide is obtainable under the trade designation Thermelt by
the firm of Bostik Findley GmbH, 33829 Borghausen. Using this known
adhesive, the advantages of the invention have appeared with
especial clarity.
[0015] The object 1 is intended for use as an intermediate between
structural parts connectable to one another. For such use, it may
be necessary to produce a considerable number of objects 1, which
are then transported to a place of use, more or less in bulk, in
suitable receptacles. Then, the objects 1, as delivered, must be
individually fed in an assembling operation. In order for such use
to be easily and quickly accomplished, by automatic means if
required, the contact surfaces 2, 3 of the objects 1 are provided
with a rough surface texture. Due to the roughness of the contact
surfaces 2, 3, the objects 1, even if the synthetic thermoplastic
material is fairly soft, have no tendency to adhere to each other,
so that they are easily separated.
[0016] The production of an object 1 of thermoplastic adhesive is
preferably performed by an injection molding process. Under heat
and pressure, plasticized synthetic adhesive is injected into
molding recesses of a cooled molding tool. After a cooling phase,
the molding tool is opened and an object, meanwhile solidified, is
removed therefrom.
[0017] In FIG. 2, a suitable molding tool 10 is represented in
section. It comprises a bottom tool half 1 1 having a recess 12
matching the shape of the object 1 and an upper tool half 13
closing the recess 12. In the upper tool half 13, a supply passage
14 is provided for feeding the plasticized adhesive.
[0018] In order to generate the rough texture of the contact
surfaces 2, 3 during the actual production of an object 1, the
matching molding surfaces 15, 16 of the tool halves 11, 13 are
provided with a rough surface of corresponding roughness depth. The
roughness of the surfaces of the tool halves 11, 13, of a
high-strength steel, for example, may advantageously be generated
by spark erosion.
[0019] The roughness of the molding surfaces 15, 16 of the molding
tool 10, besides generating rough contact surfaces 2, 3, has the
surprising advantage that after injection of the adhesive into the
molding tool 10, the object 1 is preserved in its preassigned shape
during cooling, and does not tend to shrink or warp in an undesired
manner. After a well-defined cooling phase in which the object 1
has attained a solid state, though without having been completely
cooled as yet, the molding tool is opened by taking off the tool
half 13. During cooling that continues after the molding tool has
been opened, the object 1 shrinks slightly and, due to the
roughness of the surfaces of object 1 and tool half 11 in contact
with each other, the object 1 detaches itself from the tool half 11
automatically, so that it can easily be removed or ejected from the
recess 12 of the molding tool 10.
[0020] For the purpose of the invention, an averaged German
Standard DIN 4768 roughness depth R.sub.z of the corresponding
surfaces of the object and of the molding tool from 40 to 100.mu.
is especially suitable. Preferably, the average roughness depth
lies in the range from 55 to 70.mu.. Suitable arithmetic mean
rugosities R.sub.a lie in a range from 6 to 25.mu., preferably in a
range from 10 to 15.mu., such as 12.5.mu..
[0021] The averaged roughness depth R.sub.z designates the mean
rugosity of five reference segments within an evaluation length.
The arithmetic mean rugosity R.sub.a is the arithmetic mean of the
absolute values of the profile deviations within a reference
segment.
[0022] FIG. 3 shows a preferred application of the disk-shaped
object 1. In this application, the object 1, as shown in the
left-hand half of the representation in FIG. 3, is mounted between
a plate-like part 20 and the flange 21 of a fastening element 22
inserted in an opening of the part 20, for example a bodywork
sheet. In the form shown, the fastening element 22 comprises spring
locking elements 23, bearing on the side of the substrate 20 away
from the flange 21 and pressing the fastening element 22 against
the object 1 and the part 20. The arrangement, preassembled in this
way, is then heated, in an oven, for example, to such an extent
that the thermoplastic adhesive of which the object 1 is
constituted becomes flowable. In a flowable state, the object 1 is
compressed by the contact force of the locking elements 23, as
indicated in the right-hand half of the representation in FIG. 3.
Thus, the flange 21 is drawn into contact with the part 20, the
material of the object 1 flowing into the annular gap between the
opening and the fastening element 22, and sealing it completely. By
the adhesive action of the thermoplastic adhesive of the object 1,
moreover, the load capacity of the connection between fastening
element 22 and part 20 is enhanced.
[0023] While preferred embodiments of the invention have been shown
and described, it will be apparent that modifications can be made
without departing from the principles and spirit of the invention,
the scope of which is defined in the appended claims.
* * * * *