U.S. patent application number 10/456588 was filed with the patent office on 2003-11-13 for liquid pressure transfer method, transfer film therefor and product decorated thereby.
Invention is credited to Kiyotaki, Tomomi.
Application Number | 20030211300 10/456588 |
Document ID | / |
Family ID | 17599569 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030211300 |
Kind Code |
A1 |
Kiyotaki, Tomomi |
November 13, 2003 |
Liquid pressure transfer method, transfer film therefor and product
decorated thereby
Abstract
A workpiece to which a transfer pattern is to be applied is
formed to have a rod-like element curved into a loop-like shape to
form an apparent geometric plane. A transfer film used in the
liquid pressure transfer is formed on a required portion thereof,
and the transfer pattern for decoration is formed to have a
configuration corresponding to that of the apparent plane. The
workpiece is handled so as to downwardly approach the transfer film
from a position corresponding to the transfer pattern, and is then
immersed in the transfer liquid. Consequently, the transfer film
bonds to the rod-like element of the workpiece so as to
circumferentially surround the rod-like element continuously from a
bottom of the rod-like element to a top thereof on the basis of a
diametric section of the rod-like element. Thus, the transfer
pattern is transferred to at least the rod-like element of the
workpiece.
Inventors: |
Kiyotaki, Tomomi; (Shizuoka,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
17599569 |
Appl. No.: |
10/456588 |
Filed: |
June 9, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10456588 |
Jun 9, 2003 |
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09514337 |
Feb 28, 2000 |
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6599579 |
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Current U.S.
Class: |
428/195.1 |
Current CPC
Class: |
B41M 5/025 20130101;
B62D 1/06 20130101; Y10T 428/24802 20150115 |
Class at
Publication: |
428/195.1 |
International
Class: |
B32B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 30, 1999 |
JP |
11-278602 |
Claims
What is claimed is:
1. A transfer film comprising: a film body having a transfer
operation surface defined thereon, said transfer operation surface
having a predetermined transfer pattern previously printed thereon
in transfer ink; wherein, when transfer is not to be carried out,
said transfer operation surface is coated thereon with an activator
to permit a portion of said transfer operation surface to which
said transfer ink is applied to exhibit stickiness and the transfer
film is supported on a surface of a transfer liquid while being
floated thereon, said transfer pattern being transferred to a
surface of a workpiece by a liquid pressure produced when the
workpiece is downwardly immersed in the transfer liquid; the
transfer film is applied to the workpiece including a rod-like
element curved into a loop-like shape, resulting in the workpiece
being formed with an apparent plane which permits the workpiece to
be recognized as a whole; and said transfer pattern is formed to
have a configuration corresponding to a configuration of the
apparent plane of the workpiece and arranged on a required position
of the transfer film.
2. A transfer film as defined in claim 1, wherein the workpiece is
a steering wheel; and said transfer pattern is formed to have a
substantially annular shape in correspondence to the apparent plane
of the steering wheel.
3. A transfer film as defined in claim 2, wherein said transfer
pattern is formed to have the substantially annular shape by taking
in pattern data of a plane rectangular shape and then converting
into pattern data of a round shape.
4. A transfer film as defined in claim 1, wherein said transfer
pattern is formed to have a substantially annular shape by taking
in pattern data of a plane rectangular shape and then converting
into pattern data of a round shape.
Description
[0001] This application is a Divisional application of Ser. No.
09/514,337, filed Feb. 28 2000, now allowed.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a liquid pressure transfer method,
and more particularly to a liquid pressure transfer printing method
for applying a pattern for decoration specifically intended for a
workpiece such as a steering wheel for an automobile or the like
which includes a rod-like element curved to form a predetermined
apparent plane to the workpiece.
[0003] For example, a steering wheel for an automobile has a core
made of a metal material so as to exhibit strength of at least a
predetermined level. The core is provided therearound with a grip
surface, which is formed of a material such as a plastic material,
a wooden material, a leather material or the like, which is
selected depending on requirements such as operability of the
steering wheel, decorative characteristics thereof and the like.
For example, a steering wheel provided thereon with a wooden
surface is evaluated to be a high-quality article, because it
exhibits both satisfactory operability and decorative
characteristics and requires considerable labor and time for
manufacturing. However, a recent tendency to reconsider the
easygoing use of a natural material in view of protecting the
natural environment, and a demand for reduction of a manufacturing
cost had led to development of liquid pressure transfer printing
techniques. These techniques involve transfer printing on a plastic
steering wheel material in place of a wooden steering wheel
material to apply a woodgrain pattern for decoration thereto.
[0004] Application of a decorative pattern to a workpiece by liquid
pressure transfer permits formation of a natural pattern which
exhibits satisfactory conformability to a configuration of the
workpiece, resulting in the technique being extensively practiced
on a variety of workpieces. However, application of such liquid
pressure transfer to, for example, a steering wheel encounters some
important problems. A conventional steering wheel made of a wooden
material is manufactured by subjecting two wooden rod-like
materials which are semicircular in section to a treatment by
moistening and heating to bend them into an annular shape, and then
bonding them to each other while interposing a core therebetween.
Thus, of course the wooden materials are each so arranged that a
straight grain extends in a circumferential direction of the
steering wheel. Such arrangement of the straight grain permits a
user to have a sense of security or a sense of reliability.
[0005] Unfortunately, in application of a decorative pattern to a
workpiece by liquid pressure transfer, a transfer film having a
transfer pattern formed thereon is supported on a surface of a
transfer liquid while being floated thereon, so that exact
positioning or registration between the transfer film and the
workpiece is relatively difficult. Thus, in the prior art, a
continuously-formed decorative pattern such as a woodgrain pattern,
a natural stone pattern, or a carbon fiber pattern is arranged all
over the transfer film so as to allow misregistration which occurs
between the transfer film and the workpiece. Consequently, a
decorative pattern similar to a natural material is provided
irrespective of a portion of the pattern transferred to the
workpiece. Nevertheless, development of techniques of reproducing a
transfer pattern specifically intended for a desired product such
as, for example, techniques of arranging a straight grain pattern
in a circumferential direction of a steering wheel, are still
demanded.
SUMMARY OF THE INVENTION
[0006] The present invention has been made in view of the foregoing
disadvantage of the prior art.
[0007] Accordingly, it is an object of the present invention to
provide a liquid pressure transfer method which is capable of
applying a decorative pattern specifically intended for a specific
or desired workpiece such as a steering wheel or the like to the
workpiece.
[0008] It is another object of the present invention to provide a
transfer film which is capable of facilitating application of a
decorative pattern specifically intended for a workpiece such as a
steering wheel or the like to the workpiece.
[0009] It is a further object of the present invention to provide a
product decorated according to the liquid pressure transfer method
described above.
[0010] In accordance with one aspect of the present a liquid
pressure transfer method for carrying out liquid pressure transfer
printing on a workpiece such as a steering wheel is provided. The
liquid pressure transfer method includes the step of supporting a
transfer film on a surface of a transfer liquid while floating it
thereon. The transfer film has a transfer pattern for decoration
printed thereon. The liquid pressure transfer method also includes
the step of downwardly immersing a workpiece in the transfer liquid
to transfer the transfer pattern to a surface of the workpiece, to
thereby decorate the workpiece. The workpiece includes a rod-like
element curved into a loop-like shape, resulting in it being formed
in an apparent geometric plane which permits the workpiece to be
recognized as a whole. The transfer pattern is formed to have a
configuration corresponding to a configuration of the apparent
plane of the workpiece, and is arranged on a required position of
the transfer film. The workpiece is handled so as to approach the
transfer film from a position above the transfer pattern
corresponding to the transfer pattern and is then immersed in the
transfer liquid. Therefore, the transfer film bonds to the rod-like
element of the workpiece in a manner to circumferentially surround
the rod-like element continuously from a bottom of the rod-like
element to a top thereof on the basis of a diametric section of the
rod-like element, resulting in the transfer pattern being
transferred to at least the rod-like element of the workpiece.
[0011] The liquid pressure transfer method thus constructed permits
the workpiece, such as a steering wheel or the like which includes
the rod-like element curved to form a predetermined apparent plane,
to be readily and positively decorated with a transfer pattern
specifically intended for the workpiece.
[0012] In a preferred embodiment of the present invention, an
approach attitude angle defined between the apparent plane of the
workpiece and the surface of the transfer liquid is set to be
within a range of .+-.15.degree.. This permits the optimum approach
attitude angle to be set depending on a type of the transfer
pattern, as well as a size of the workpiece, a configuration
thereof and the like.
[0013] In a preferred embodiment of the present invention, the
workpiece is immersed in the transfer liquid in a substantially
vertical direction. Such vertical lowering of the workpiece to the
surface of the transfer liquid facilitates transfer of the transfer
pattern to the workpiece.
[0014] In a preferred embodiment of the present invention, the
transfer film is provided thereon with reference position marks for
enabling relative registration between the transfer pattern and the
workpiece. This permits positioning or registration between the
transfer pattern and the workpiece to be readily attained while
preventing misregistration of the transfer film.
[0015] In accordance with another aspect of the present invention,
a transfer film is provided. The transfer film includes a film body
which has a transfer operation surface defined thereon. The
transfer operation surface has a predetermined transfer pattern
previously printed thereon in transfer ink. When transfer is to be
carried out, the transfer operation surface is coated thereon with
an activator to permit a portion of the transfer operation surface
to which the transfer ink is applied to exhibit stickiness. The
transfer film is supported on a surface of a transfer liquid while
being floated thereon. The transfer pattern is transferred to a
surface of a workpiece by a liquid pressure produced when the
workpiece is downwardly immersed in the transfer liquid. The
transfer film is applied to the workpiece including a rod-like
element curved into a loop-like shape, resulting in the workpiece
being formed with an apparent plane which permits the workpiece to
be recognized as a whole. The transfer pattern is formed to have a
configuration corresponding to a configuration of the apparent
plane of the workpiece and arranged on a required position of the
transfer film. The transfer film thus constructed permits the
transfer pattern specifically intended for the workpiece to be
readily applied to the workpiece, to thereby facilitate decoration
of the workpiece.
[0016] In a preferred embodiment of the present invention, the
workpiece is a steering wheel. The transfer pattern is formed to
have a substantially annular shape in correspondence to the
apparent plane of the steering wheel. Thus, in the present
invention, although distortion of the pattern is varied depending
on a position on a circumference of a diametric section of the
rod-like element of the workpiece, the pattern distortion in a
circumferential direction of the whole steering wheel is
substantially the same irrespective of a position on the rod-like
element in the circumferential direction thereof Thus, the transfer
printing may be carried out while rendering the pattern distortion
inconspicuous.
[0017] In a preferred embodiment of the present invention, the
transfer pattern is formed to have a substantially annular shape by
taking in pattern data having a plane rectangular shape and then
converting the pattern data into pattern data having a round shape.
This permits the transfer pattern specifically intended for the
workpiece to be more exactly reproduced on the workpiece.
[0018] In accordance with a further aspect of the present
invention, there is provided a decorated product to which a
predetermined decorative pattern is applied by subjecting a
workpiece such as a steering wheel or the like including a rod-like
element to liquid pressure transfer printing in which the workpiece
is downwardly immersed in a transfer liquid which supports a
transfer film having a transfer pattern for decoration printed on a
surface thereof while floating it on the transfer liquid.
Therefore, the transfer pattern is applied to at least the rod-like
element of the workpiece. The workpiece is operated so as to permit
the transfer pattern to be printed on the rod-like element of the
workpiece in a manner to circumferentially surround the rod-like
element continuously from a bottom of the rod-like element to a top
thereof on the basis of a diametric section of the rod-like
element. Consequently, transfer of the transfer pattern to the
workpiece is carried out according to the above-described liquid
pressure transfer method while ensuring exact reproducibility of
the transfer pattern.
[0019] Such construction permits the transfer pattern to be more
exactly reproduced on a variety of workpieces of a closed loop
shape or an open loop shape including, for example, a hula hoop,
rings in gymnastic, a towel ring, a chair back, a handrail and the
like in addition to the steering wheel while minimizing distortion
of the transfer pattern.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] These and other objects and many of the attendant advantages
of the present invention will be readily appreciated as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings; wherein:
[0021] FIG. 1A is a schematic side elevation view showing an
apparatus which is adapted to practice a liquid pressure transfer
method according to the present invention, wherein an immersion
angle is set to be 0.degree. by way of example;
[0022] FIG. 1B is an enlarged partial cross sectional view of part
1B of FIG. 1A;
[0023] FIG. 2 is a schematic side elevation view showing the
apparatus which is adapted to practice a liquid pressure transfer
method according to the present invention, wherein the immersion
angle is set to be 20.degree.;
[0024] FIGS. 3A to 3C are plan views showing a transfer pattern
formed on a transfer film;
[0025] FIG. 4A is a perspective view showing a steering wheel which
is an example of a decorated product according to the present
invention;
[0026] FIG. 4B is a sectional view taken along line 4B-4B of FIG.
4A;
[0027] FIGS. 5A to 5C are schematic views showing steps of liquid
pressure transfer by stages, respectively;
[0028] FIG. 6 is a schematic side elevation view showing a unit for
continuously feeding a transfer film to a transfer bath, in which a
transfer liquid flows; and
[0029] FIG. 7 is a schematic view showing a procedure for
converting pattern data of a rectangular shape into pattern data of
an annular shape.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Now, the present invention will be described in detail with
reference to the accompanying drawings. The following description
will be first made on a workpiece to be decorated according to the
present invention. Then, a liquid pressure transfer printing
apparatus for carrying out liquid pressure transfer printing on
such a workpiece is schematically described. Subsequently, a liquid
pressure transfer printing method according to the present
invention will be described together with a manner of operation of
the liquid pressure transfer printing apparatus.
[0031] A workpiece designated by reference character W in FIGS. 1A,
1B and 2 includes a rod-like element formed to be curved to define
a predetermined apparent geometric plane R which permits the
workpiece to be recognized as a whole. Thus, the workpieces to
which the present invention is applicable may include, for example,
a steering wheel mounted on a vehicle or the like, as well as
products of an annular shape, a substantially O-shape or the like
which form a closed loop such as a hula hoop, rings in gymnastics,
a towel ring and the like, and products of a substantially U-shape
which form an open loop such as a chair back and the like. Further,
the workpieces may include products such as a handrail for stairs
and the like wherein two loop-like members are connected together
through one or two straight members.
[0032] The apparent plane R is defined as a plane literally when
the present invention is applied to a steering wheel as the
workpiece W. However, it is not necessarily defined as a plane when
the present invention is applied to a chair back as the workpiece
W. In that case, the apparent plane R may be often defined so as to
somewhat have a curvature.
[0033] Also, the illustrated embodiment will be described
essentially in connection with the case that the present invention
is applied to a steering wheel as the workpiece W. Thus, when it is
necessary to distinguish a steering wheel before the liquid
pressure transfer printing of the present invention from a steering
wheel after the transfer printing, a steering wheel which has been
subjected to the liquid pressure transfer printing is designated by
reference character 1, and a steering wheel before the printing is
designated by 1A.
[0034] Now, the steering wheel 1 which has been subjected to the
liquid pressure transfer printing will be described with reference
to FIGS. 4A and 4B by way of example. The steering wheel 1 includes
a boss section 2 acting as a center of rotational movement of the
steering wheel 1, spoke sections 3 arranged so as to radially
extend from the boss section 2, and a rim section 4 connected to a
distal end of each of the spoke sections 3 and formed to have a
substantially annular shape. The rim section 4, as shown in FIG.
4A, includes a long rim portion 41 of an elongated arcuate shape
(positioned on an upper side in FIG. 4A), a short rim portion 42 of
a short arcuate shape (positioned on a lower side in FIG. 4A), and
two grip portions 43 for connecting the long rim portion 41 and
short rim portion 42 to each other therethrough (positioned on both
lateral sides in FIG. 4A). The long rim portion 41 and short rim
portion 42 have a transfer pattern P specifically intended for the
workpiece W such as a woodgrain pattern, a straight grain pattern
or the like, applied thereto and is formed thereon with a
topcoat.
[0035] The grip portions 43 are each connected to the spoke
sections 3 which extend from the boss section 2. It is considered
that the spoke sections 3 cause force which is different from that
acting on the other portions, such as the long rim portion 41 and
short rim portion 42, to act on the transfer film F during the
transfer. This prevents liquid pressure transfer printing like that
carried out on the other portions to be attained on the grip
portions 43. Thus, for example, techniques of wrapping a suitable
material such as leather or the like around the grip portions 43
may be employed after transfer printing, to thereby hide printing
applied to the grip portions 43 or to apply a special decoration
effect or a grip feel to the grip portions. However, unless
printing applied to the grip portions 43 adversely affects an
appearance of the product or causes any problem, such techniques
may be eliminated. Also, when it is not desired to apply liquid
pressure transfer printing to the grip portions 43, they may be
covered with any suitable masking material in advance.
[0036] In printing applied to the rim section 4, the transfer
pattern P specifically intended for the workpiece W or steering
wheel 1A is transferred to the rim section 4, wherein the
illustrated embodiment permits pattern distortion to be
inconspicuous as compared with the prior art. This is due to the
fact that the transfer pattern P is substantially formed to have an
annular shape corresponding to a configuration of the steering
wheel 1A. More particularly, in a diametric section of the rod-like
element of the steering wheel 1A or a section of the rod-like
element of the steering wheel taken in a diametric direction of the
rod-like element, distortion of the transfer pattern P is varied
depending on a position on a circumference of the diametric section
of the rod-like element. However, the pattern distortion in a
circumferential direction of the whole steering wheel 1A is
substantially the same irrespective of positions thereof. This
permits the pattern distortion on the whole steering wheel 1A to be
inconspicuous as a whole. The transfer pattern P is so arranged
that a joint line Pa of the transfer pattern P is positioned on a
rear surface of the steering wheel 1 which is substantially out of
sight of a driver when the steering wheel is mounted in a
vehicle.
[0037] Now, a liquid pressure transfer printing apparatus 10 will
be described with reference to FIG. 1A by way of example. The
liquid pressure transfer printing apparatus 10 includes a transfer
bath 11, a transfer film storage unit (not shown) and a workpiece
holding unit 13.
[0038] The transfer bath 11 has a transfer liquid L stored therein,
and a transfer film F is supported on a surface of the transfer
liquid L while being floated thereon. In the illustrated
embodiment, the transfer films formed in individual sheets are fed
to the transfer bath 11 one by one by hand so as to be floated on
the transfer liquid L, so that the transfer liquid L is always kept
stationary.
[0039] The transfer film storage unit is constructed so as to
permit the transfer films F to be taken out thereof one by one.
[0040] The transfer film F may be formed to have a rectangular
configuration as shown in each of FIGS. 3A to 3C by way of example.
The transfer film F includes a film body which has a transfer
operation surface defined thereon. The transfer operation surface
has the transfer pattern P for decoration formed only on a required
position thereof corresponding to a configuration of the apparent
plane R of the workpiece W. In the illustrated embodiment, the
transfer pattern P is formed to have a substantially annular shape
corresponding to the configuration of the rim section 4 of the
steering wheel 1. Also, the transfer film F is suitably provided
thereon with reference position marks M which permit relative
positioning or registration between the transfer pattern P and the
workpiece W to be carried out therethrough. In the illustrated
embodiment, the reference position marks M include a cross-like
mark arranged on a substantially central position of the transfer
pattern, four radial marks arranged at substantially equal angular
intervals on an outside of the transfer pattern P, and the like by
way of example, as shown in each of FIGS. 3A to 3C.
[0041] A transfer film F shown in FIG. 3A is adapted to be directed
to decoration of the workpiece W carried out when the workpiece W
is vertically lowered to the surface of the transfer liquid L while
maintaining an approach attitude angle .alpha. of the workpiece W
at 0.degree.. The transfer film F of FIG. 3A has a transfer pattern
P of a substantially concentric shape formed thereon with high
accuracy. A transfer film F shown in FIG. 3B is directed to the
decoration when the workpiece W is vertically lowered to the liquid
surface while maintaining the approach attitude angle .alpha. at
suitable degrees. Thus, the transfer film F of FIG. 3B corresponds
to that shown in FIG. 1. The transfer film F of FIG. 3B has a
transfer pattern P which is formed to have a substantially annular
shape provided thereon, wherein a major axis Ac and a minor axis At
thereof extend in a vertical direction and a horizontal direction
of FIG. 3B, respectively. A transfer film F shown in FIG. 3C is
directed to decoration of the workpiece W when it is obliquely
lowered to the liquid surface while maintaining an approach
attitude angle .alpha. thereof at suitable degrees. The transfer
film F corresponds to that described hereinafter with reference to
FIG. 2. Thus, the transfer film F of FIG. 3C has a transfer pattern
P formed to have a substantially annular shape, wherein a minor
axis At and a major axis Ac thereof extend in a vertical direction
and a horizontal direction of FIG. 3C, respectively. The term
"substantially annular shape" referred to herein indicates such
configurations as shown in FIGS. 3A to 3C. Thus, the substantially
annular shapes include a substantially complete annular shape as
shown in FIG. 3A, as well as somewhat deformed annular shapes as
shown in FIGS. 3B and 3C. Therefore, as seen in the attached
drawings, the transfer pattern is printed only on an area of the
transfer film F that has a shape corresponding to a surface shape
of the workpiece W to be covered by the transfer pattern. Also, the
transfer film F shown in each of FIGS. 3A to 3C has only one
transfer pattern P printed thereon. Alternatively, the transfer
film may have a plurality of transfer patterns P printed
thereon.
[0042] Further, forming the transfer pattern P into a substantially
annular shape for the purpose of transferring, for example, a
woodgrain pattern to the workpiece is carried out by subjecting an
image of a woodgrain actually photographed to image processing by
means of a computer or preparing a picture of a woodgrain directly
by means of a computer, to thereby convert a pattern to be
transferred into pattern data of a plane rectangular shape. Then,
the plane rectangular pattern data thus converted are converted
into pattern data of a round or ring-like shape on the computer,
resulting in the transfer pattern P being formed to have a
substantially annular shape. Thus, it will be noted that when the
plane rectangular pattern before the conversion is represented in a
coordinate system containing X and Y coordinate axes which are
perpendicular to each other as shown in FIG. 7, the conversion
permits the X axis to be converted into a circumferential direction
and the Y axis to be converted into a radial direction, resulting
in the transfer pattern P of a substantially annular shape being
provided. Of course, the operation of joining opposite ends of the
plane rectangular shape to each other is carried out with suitable
image processing for rendering the joint inconspicuous, such as
connecting woodgrain lines to each other.
[0043] The above description has been made for conversion of the
transfer pattern into a round shape carried out immediately after
taking in the transfer pattern as the pattern data of a plane
rectangular shape. However, for example, it is considered that the
pattern data photographed may be too small to be developed in the
circumferential direction. More particularly, the pattern data of a
plane rectangular shape indicated by solid lines shown in FIG. 7
have a dimension in the X axis direction sufficient to be converted
into the circumferential direction. However, the pattern data
having such a large size is not necessarily photographed. In order
to solve the problem, an approach may be employed which is
constructed so as to introduce pattern data of a small size readily
photographed into an image processing unit and to repeat the
pattern data to prepare plane rectangular pattern data of a desired
large size.
[0044] Another approach which may be employed is to introduce
pattern data of a small size into an image processing unit and then
independently multiply a longitudinal dimension of the pattern data
and a lateral dimension thereof on a screen of the unit to obtain
plane rectangular pattern data of a desired size. Repeating of such
small-sized pattern data for formation of such plane rectangular
pattern data of a desired size may be carried out on the same
pattern. Alternatively, patterns different from each other may be
connected to each other. The operation of multiplying the
longitudinal dimension and lateral dimension independently from
each other is effective to not only convert the pattern data into a
desired size but also, for example, to set the density of woodgrain
lines at a suitable level.
[0045] The workpiece holding unit 13 functions to immerse the
steering wheel 1A into the transfer liquid L while holding it. In
the immersion, an approach attitude angle .alpha. defined between
the apparent plane R of the workpiece W and the surface of the
transfer liquid L is set to be within a range of .+-.15.degree.
based on a horizontal direction. The symbols "+" and "-" referred
to herein do not have any specific definition. They merely mean
that one rotational direction from a certain reference position
indicates "+" and the other rotational direction indicates "-".
Also, in the illustrated embodiment, the workpiece W is immersed in
the transfer liquid L in a vertical direction as shown in FIG. 1A.
However, a direction of immersion of the workpiece W may be
suitably varied. In the present invention, the direction of
immersion is indicated by an angle .beta. between the direction of
immersion and a line normal to the surface of the transfer liquid,
which angle is defined to be an immersion angle herein. When the
workpiece is immersed in the normal direction as shown in FIG. 1A,
the immersion angle is defined to be 0.degree., that is, the
workpiece is vertically lowered. The approach attitude angle at and
immersion angle .beta. are each suitably set depending on various
factors such as a size of the transfer pattern P, a size of the
steering wheel 1A, a thickness of the rod-like element, and the
like. However, the angles set are not necessarily kept constant
during transfer of the transfer pattern to the workpiece. For
example, when the apparent plane R of the workpiece W somewhat has
a curvature, the angle may be suitably varied after start of the
immersion. For example, in the immersion shown in FIG. 2, the
approach attitude angle .alpha. and immersion angle .beta. are set
to be 10.degree. and 20.degree., respectively.
[0046] Now, liquid pressure transfer printing on the workpiece such
as a steering wheel or the like will be described in relation to
operation of the liquid pressure transfer printing apparatus 10
thus constructed.
[0047] (1) Feeding of the Transfer Film:
[0048] First, the transfer film F is fed onto the transfer liquid L
in the transfer bath 11 while an activator is coated on a surface
of the transfer film F to which a transfer ink is applied. The
activator may be made by, for example, mixing a resin material, a
pigment, a solvent, a plasticizer and the like with each other at
suitable ratios. Alternatively, a solvent such as a thinner or the
like may be merely used as the activator. Thus, the term
"activators" referred to herein include a thinner and the like. The
transfer film F thus coated thereon with the activator absorbs
water, to thereby be softened and swollen, resulting in it somewhat
extending in all directions. Coating of the activator on the
transfer film F is necessary because the transfer film F is
normally stored while the applied transfer ink is kept dry. Thus,
the coating permits the ink coated surface of the transfer film F
to be provided with stickiness, so that the ink on the transfer
film F may be transferred. Also, coating of the activator on the
transfer film F may be carried out after feeding of the transfer
film F onto the transfer liquid L as well. Thus, the terms "the
activator is coated on the transfer film to provide the ink coated
surface of the transfer film with stickiness and permit the
transfer film to be floated on the transfer liquid" referred to
herein or an expression similar thereto does not limit the steps to
any specific order. Thus, in the present invention, coating of the
activator may be carried out either after floating of the transfer
film F on the transfer liquid or prior thereto.
[0049] (2) Feeding of Steering Wheel:
[0050] The workpiece W or steering wheel 1A is set so that a front
surface thereof (defined by the time when it is mounted in a
vehicle) is kept facing the transfer film F. This permits the joint
line Pa of the transfer film F to be positioned on a side of a rear
surface of the steering wheel which is substantially out of sight
of a driver. Then, the steering wheel 1A is immersed in the
transfer liquid L while being suitably maintained at an approach
attitude angle .alpha. and an immersion angle .beta. by the
workpiece holding unit 13. The approach attitude angle .alpha. and
immersion angle .beta. are not necessarily kept constant during the
transfer. The angles .alpha. and .beta. may be suitably varied
depending on the apparent plane R formed or the like after the
start of the immersion as well. Also, the transfer film F, as
described above, may be provided thereon with the reference
position marks M for relative registration between the transfer
pattern P and the workpiece W. Such arrangement of the reference
position marks M permits a position at which immersion of the
steering wheel 1A is started to be readily determined.
[0051] (3) Transfer:
[0052] When the steering wheel 1A is immersed in the transfer
liquid L, the transfer film F is continuously bonded to the
steering wheel 1A, so that the transfer pattern P may be
transferred to the steering wheel 1A while keeping distortion of
the pattern P inconspicuous. The transfer may be carried out as
shown in FIGS. 5A to 5C by way of example. More particularly, the
transfer film F circumferentially surrounds the rod-like element
continuously from a bottom of the rod-like element to a top thereof
on the basis of a diametric section of the rod-like element with
progress of immersion of the steering wheel 1A in the transfer
liquid L, so that the transfer film F ultimately forms the joint
line Pa when it reaches the rear surface side of the steering wheel
1A. Then, the joint line Pa is formed on a whole circumference of
the rear surface of the steering wheel 1A, resulting in the
transfer being substantially completed.
[0053] Now, distortion of the transfer pattern P on the steering
wheel 1A will be described. First, it is supposed that on a
circumference of the diametric section of the rod-like element of
the steering wheel 1A, a lowermost point at which the transfer is
first initiated, an uppermost point at which the joint line Pa of
the transfer pattern P is formed, an innermost peripheral point
positioned between the lowermost point and the uppermost point, and
an outermost peripheral point positioned therebetween are
designated by reference characters P0, P1, P2 and P3 in FIG. 1B,
respectively. In this instance, in a region in which the transfer
is carried out from the lowermost point P0 through the innermost
peripheral point P2 to the uppermost point P1, a radius of the
rod-like element projected on a horizontal plane is gradually
decreased from the lowermost point P0 to the innermost peripheral
point P2 and gradually increased from the innermost peripheral
point P2 to the uppermost point P1. Consequently, in a region where
the transfer is carried out from the lowermost point P0 through the
outermost peripheral point P3 to the uppermost point P1, the radius
of the rod-like element projected on a horizontal plane is
gradually increased from the lowermost point P0 to the outermost
peripheral point P3 and gradually decreased from the outermost
peripheral point P3 to the uppermost point P1.
[0054] In order to eliminate distortion of the transfer pattern
over the whole circumference or periphery of the diametric section
of the rod-like element of the steering wheel 1A, the transfer
pattern P would be preferably formed so as to permit such a radius
of the rod-like element projected on a horizontal plane to be
substantially exactly reproduced. However, this is highly
difficult. Therefore, the actual transfer pattern P to be printed
is formed to have a substantially annular shape so that the radius
projected on a horizontal plane is increased in one direction
toward an outside of the transfer pattern. This of course causes
the transfer pattern to be subject to distortion, so that a degree
of pattern distortion on the circumference or periphery of the
diametric section of the rod-like element is of course varied
depending on a position on the circumference of the section.
However, the transfer film F is softened and swollen due to
immersion thereof in the transfer liquid L, resulting in
substantially extending in all directions, so that the lowermost
point P0, uppermost point P1, innermost peripheral point P2 and
outermost peripheral point P3 are substantially identical in
pattern distortion in a peripheral or circumferential direction of
the whole rod-like element with each other. This permits the
pattern distortion on the whole steering wheel 1A to be
inconspicuous.
[0055] (4) Removal of Film and Drying:
[0056] The steering wheel 1A which has been thus subjected to the
liquid pressure transfer printing has a residue of the transfer
film F which has not been dissolved in the transfer liquid L
adhered thereto. Thus, in order to fully remove the residue, the
steering wheel 1A is subjected to washing by showering or the like,
followed by drying.
[0057] (5) Topcoat
[0058] The steering wheel 1A having the transfer pattern thus
printed thereon provides the decorated product of the present
invention. However, when it is desired that a portion of the
steering wheel which has been subjected to the transfer printing
exhibit increased gloss and depth of a color, a transparent topcoat
is formed thereon by spraying or the like. The topcoat thus formed
may be subjected to polishing by buffing or the like.
[0059] In the illustrated embodiment, the transfer films F formed
in individual sheets are fed one by one by hand to the transfer
bath 11 in which the transfer liquid L is kept stationary so that
they may be floated on the transfer liquid L. Alternatively, the
present invention may be constructed in such a manner that a
transfer film F is continuously fed to the transfer bath 11 in
which the transfer liquid L is kept flowing. In this instance, the
steering wheel 1A may be vertically lowered to the transfer bath
11. Alternatively, the steering wheel may be obliquely lowered to
the transfer bath by means of a conveyor of an inverted triangular
configuration, an articulated robot or the like. Also, coating of
the active agent on the transfer film F may be carried out either
before feeding of the transfer film F to the transfer bath 11 or
thereafter.
[0060] Referring now to FIG. 6, another embodiment of the present
invention is illustrated. The embodiment shown in FIG. 6 is
constructed so as to continuously feed a transfer film F to a
transfer bath 11. For this purpose, the transfer bath 11 is
provided thereon with a circulation pipe line 14 and a pump 15, so
that a transfer liquid L may be slowly circulated as indicated by
an arrow in FIG. 6. Also, the transfer bath 11 is provided on each
of opposite side ends thereof with a guide chain 16. Further, the
transfer bath 11 is provided with a fan unit 17, which is
positioned on an upstream side of the transfer liquid L. Thus, the
transfer liquid L circulated, the guide chains 16, the fan unit 17
and the like cooperate with each other to permit the transfer film
F floatedly supported on a surface of the transfer liquid L to be
carried toward a workpiece W or a steering wheel 1A while
preventing waves from forming in the transfer liquid L.
[0061] Also, in the illustrated embodiment, a transfer film feed
unit 12 is substituted for the transfer film storage unit
incorporated in the embodiment described above. The transfer film
feed unit 12 includes a film roll 18 constituted by winding a
water-soluble transfer film F in a roll-like manner, a solvent tank
19 having an activator S stored therein, and feed rollers 20. The
transfer film F delivered from the film roll 18 is activated by the
activator S in the solvent tank 19 and then continuously fed to the
transfer bath 11.
[0062] After the transfer film F fed to the transfer bath 11 which
is thus activated is carried to a suitable position, the steering
wheel 1A is immersed in the transfer bath 11 by means of a
workpiece holding unit 13. Operation of transferring a transfer
pattern P from the transfer film F to the workpiece W in the
illustrated embodiment is carried out in substantially the same
manner as that in the embodiment described above.
[0063] As can be seen from the foregoing, the present invention
permits the workpiece such as a steering wheel or the like
including the rod-like element curved to form the apparent plane to
be readily and positively decorated with the transfer pattern
specifically intended for the workpiece.
[0064] Also, the present invention permits the approach attitude
angle and/or immersion angle to be optimally set depending on a
type of the transfer pattern, as well as a size of the workpiece, a
configuration thereof and the like.
[0065] Further, positioning or registration between the transfer
pattern of the transfer film floatedly supported on the transfer
liquid and the workpiece is relatively readily attained, to thereby
prevent misregistration of the transfer film.
[0066] Moreover, distortion of the pattern is varied depending on a
position on the periphery of the diametric section of the rod-like
element of the workpiece. However, the pattern distortion is
substantially the same irrespective of a position on the
circumference of the whole rod-like element. Thus, the transfer
printing may be carried out while rendering the pattern distortion
inconspicuous.
[0067] While preferred embodiments of the invention have been
described with reference to the drawings, obvious modifications and
variations are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced other than as specifically
described.
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