Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SUPPORT AND METHOD OF SHAPING WORKPIECE AND SUPPORT
[Technical Field]
[0001]
The present invention relates to a support that supports
a workpiece which is to be produced by a three-dimensional shaping
system, and to a method of shaping the workpiece and the support.
[Background Art]
[0002]
A support for supporting a workpiece that is to be worked
from below with a tool or the like differs in its shape and size
according to the shape and size of the workpiece, and once working
of the workpiece has been completed, it is removed from the
workpiece and disposed away.
[0003]
In the prior art, however, columnar or tubular shapes are
employed as supports for the most part, as a construction
exhibiting excess strength beyond what is necessary for support
from below the workpiece.
[0004]
Consequently, multiple tools and special machines must
necessarily be used for disposal, which requires a great amount
of additional labor.
[0005]
Moreover, excessively strong supports incur needless
material costs, which is disadvantageous in terms of production
cost.
[0006]
Patent Document 1 describes a method for producing a
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three-dimensional object, wherein a support structure 21 on the
lower end is divided into a core region 22 and an external capsule
23 serving as a connecting region, with softer irradiation during
solidification of the external capsule 23 by laser light ( [Fig.
2], p.8, lines 20-21, p.91 line 3) .
However, the core region 22 shown in Fig. 2 of the
aforementioned publication has a material-filled structure, and
this has necessitated excessive material cost.
In regard to the aforementioned core region 22, Patent
Document 1 states: "It is solidified in separate distant partial
regions. Each region is either completely unconnected, or
connected via a connecting web." (p.8, lines 5 to 4 from bottom)
thereby disclosing the structure other than the filled structure,
but this description is unclear and does not concretely specify
the structure of the core region 22.
Patent Document 2 discloses the construction of a
lattice-like support structure with thin sheets mutually
crossing at a specified angle (Fig. 9, claim 2, p.3, lower left
column, line 3 from bottom to lower right column, line 1 from
top) .
However, Patent Document 2 does not disclose or suggest in
any way the relationship between the strength at the connecting
region between the support structure and the object to be
supported above, and the strength at the other regions.
[Prior Art Documents]
[Patent Documents]
[0007]
Patent Document 1: Japanese Announced Unexamined Patent
Application No. H09-511705A
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Patent Document 2: Japanese Published Unexamined Patent
Application No. H03-136834A
[Summary of Invention]
[Problem to be solved]
[0008]
An object of the present invention is providing a support
for supporting a workpiece from below efficiently with reducing
the amount of necessary materials, and providing a shaping method
for shaping the workpiece and support efficiently.
[Solution for Problem]
In order to solve the aforementioned problems, the present
invention has the following basic features.
(1) A hollow state support for supporting a workpiece from
below has a lattice form with crossing of straight linear or curved
columnar bodies, wherein a sintered strength at a connecting
region with the workpiece is lower than the sintered strength
at the other regions, and wherein the thicknesses of the columnar
bodies are uniform.
(2) A method of shaping a support, employing a
three-dimensional shaping system that carries out lamination
consisting of repeating alternation of a powder layer-forming
step and a sintering step in which the powder layer is sintered
by irradiation with a moving laser beam or electron beam, wherein
the object of shaping at the upper region is a workpiece and the
object of shaping at the lower region is a support according to
(1) above, and wherein the degree of sintering of one or several
powder layers formed between the top end of the support and the
bottom end of the workpiece is lower than the degree of sintering
at the other lower side shaping regions of the support.
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[Advantageous Effects of Invention]
[0009]
In the basic construction (1) , the support is hollow,
whereby the load of the workpiece is distributed in an essentially
uniform state so that both bearing of the load and economy of
materials is achieved.
It may be apparently grounded by the fact that the columnar
bodies forming the lattice form according to basic construction
(1) does not have a thin sheet in-between as in Patent Document
2.
Furthermore, since the sintered strength in the region in
contact with the workpiece is lower than in the other regions,
it is possible to easily cut off the support of the columnar bodies
from the workpiece.
[0010]
According to basic construction (2) , it is possible to
efficiently accomplish the operation of employing a
three-dimensional shaping system and shaping the workpiece and
the support of basic construction (1) at the same time.
[Brief Description of the Drawings]
[0011]
Fig. 1 is a lateral cross-sectional view showing an
embodiment that employs a lattice form created by crossing of
columnar bodies, as the hollow form of the support of basic
construction (1) , wherein (a) shows a case of a lattice form in
which each lattice section is obliquely crossing with the
vertical direction, (b) shows a case of a lattice form in which
portions coincide with the vertical direction and the remaining
portions are perpendicular to that direction, and (c) shows a
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case of a lattice form in which each lattice section is in the
vertical direction at the bottom end and, due to successive
curving, is in the horizontal direction at the top end.
Fig. 2 is a cross-sectional view in the vertical direction,
for an embodiment of a support with a lattice form according to
basic construction (1) , wherein the surface that is to support
the workpiece is formed at the top end.
Fig. 3 is a lateral cross-sectional view, for an embodiment
of the shaping method of basic construction (2) wherein a support
with a lattice form is shaped.
Note that the dotted lines indicate the state of control
data transmission from a controller to different operating parts.
[Description of Embodiments of the Invention]
[0012]
To compare again the construction of basic construction (1)
and a lattice form produced by crossing the thin sheet-like
supports described in Patent Document 2 (hereunder referred to
as "thin sheet-like lattice form") , if it is considered that the
linear crossing portions of the thin sheet-like lattice form
exhibit the necessary indispensable function for supporting a
weight while preventing their own deformation, the columnar
lattice form employed by basic construction (1) is evaluated as
a structure in which the region of the thin sheet itself is
abstracted from the thin sheet-like lattice form, selecting
linear crossing sections that support a weight while preventing
deformation.
By thus abstracting the region of the thin sheet itself
while selecting linear crossing sections from the lattice form,
it is possible to achieve both support of the load of the workpiece
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2 and reduction in materials.
[0013]
In basic configuration (1), a columnar lattice form with
a uniform thickness is employed, as shown in Fig. 1(a), (b) and.
(c)
So, in basic configuration (1), the cross-sectional area
of each region does not change, it is possible to avoid the
excessive use of material for formation of extra regions with
insignificant and unnecessary thicknesses, resulting from the
use of prescribed thicknesses for small sections that is
necessary to prevent breakage caused by concentration of strain
at sections with small cross-sectional areas when the thickness
is not uniform.
[0014]
In basic construction (1), for an embodiment in which the
cross-sectional area in the horizontal direction gradually
increases toward the lower side, it is possible to prevent
overturning of the support 1 even when the location supporting
the workpiece 2 is high, and this likewise applies to the lattice
forms of Fig. 1(a), (b) and (c).
[0015]
Fig. 1(a) shows the state of an embodiment wherein each
lattice section is set in a slanted direction with respect to
the vertical direction along the direction in which the workpiece
2 is supported.
As shown in Fig. 1(a), vertical lattice sections are set
crossing with each lattice section at the horizontal ends, and
horizontal lattice sections are set crossing with each lattice
section at the lower end, thereby allowing stable support of the
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workpiece 2 to be achieved, and this likewise applies for the
embodiment shown in Fig. 1(c) .
[0016]
In the case of a lattice form obliquely crossing with the
vertical direction, a bending moment M is generated in each
cross-section of the lattice form due to the load of the workpiece
2, and if the curvature radius with bending by bending moment
M is represented as p, then the following basic general formula
is valid:
[0017]
[Formula 1]
/M
(where E is the modulus of longitudinal elasticity, or Young's
modulus, and I is the secondary moment of the cross-section) .
[0018]
As clearly seen from this general formula, in order to
reduce deformation with a larger value for the curvature radius
p, a material may be selected having a cross-sectional shape
(specifically, a cross-sectional circular shape) with a large
Young's modulus E and a large secondary moment I.
[0019]
Such a material is selected based on whether, in concrete
experimentation using lattice-shaped supports 1 conforming to
different workpieces 2, the support 1 does not only not break
but also essentially does not deform.
[0020]
Fig. 1(b) shows the state of an embodiment in which sections
of each lattice match the vertical direction along the direction
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in which the workpiece 2 is supported, and the remaining sections
are perpendicular to the vertical direction.
[0021]
For this embodiment, if the load of the workpiece 2 acting
on the cross-section of each lattice form is represented as F
and the length of displacement in the vertical direction at the
top end of the cross-section of the lattice form is represented
as x, then the following basic general formula is valid:
[0022]
[Formula 2]
F/-Ex0
S- L
(where S is the cross-sectional area, E is the Young's modulus
and L is the length of the support in the vertical direction).
[0023]
As clearly seen from this general formula, in order to
reduce x which represents the degree of deformation, a material
may be selected having a high Young's modulus for a given
cross-sectional area S.
[0024]
Fig. 1(c) shows an embodiment set so that each lattice
section is in the vertically oriented at the bottom end, and
successively curves to change oriented horizontally at the top
end.
[0025]
In this embodiment, at the lower end and its vicinity,
displacement occurs according to the general formula of [Formula
2] above, while the other regions resolve to a bending moment
M according to the general formula of [Formula 1] above.
[0026]
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In the case of this embodiment, the support 1 may support
the workpiece 2 in a pressure-resistant state at the lower end
and its vicinity, while at the upper end, it may support the
workpiece 2 in a stable manner by the horizontal lattice sections.
[0027]
Such a material is selected based on whether, in concrete
experimentation using lattice-shaped supports 1 conforming to
different workpieces 2, the support 1 does not only not break
but also essentially does not deform.
[0028]
From the viewpoint of convenience of removing the support
1 in basic construction (1) , as shown in Fig. 1 (a) , an embodiment
may be employed wherein a notch 11 for inserting the operator's
fingers when cutting the support 1 off from the workpiece 2, is
provided horizontally at or near the top end of the lattice form.
[0029]
In the case of this embodiment, the operator inserts his/her
own hand into the notch 11 to allow smooth removal of the support
1 from the workpiece 2.
[0030]
When the lattice form extends up to the top end of the support
1 in basic construction (1), support of the workpiece 2 may be
unstable.
[0031]
Considering such conditions, basic construction (1) may
employ an embodiment in which a flat surface or curved surface
14 for supporting the workpiece 2 is formed at the top end of
the lattice form, as shown in Fig. 2 (a flat surface is shown
in Fig. 2) .
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[0032]
When the workpiece 2 has been situated on the flat surface
or curved surface 14, the support 1 supports the workpiece 2 in
a stable manner.
[0033]
In the shaping method according to basic construction (2) ,
as shown in Fig. 3, a three-dimensional shaping system is employed
and the workpiece 2 is shaped in the upper region, while the
support 1 of basic construction (1) is shaped in the lower region.
[0034]
In this three-dimensional shaping system, similar to a
common three-dimensional shaping system, a laser beam or electron
beam supply 5, a scanner 6, a powder supply tool 7, a squeegee
8, a table 9 and a controller 10 are employed as essential
constituent elements.
[0035]
In basic configuration (2) , the degree of sintering of one
or several powder layers formed between the top end of the support
1 and the bottom end of the workpiece 2 is lower than the degree
of sintering at the other lower side shaping regions of the support
1.
[0036]
In basic configuration (2) having this feature, at the stage
of completion of the single step in which the support 1 and the
workpiece 2 have both been shaped, a region is formed between
them wherein the degree of sintering is lower than the degree
of sintering of the support 1, and it is possible to easily
separate the two.
[0037]
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The small degree of sintering referred to here, which is
sufficient for the need, is a degree of sintering that may barely
maintain bonding between the workpiece 2 and the support 1 without
separation between them even when vibration is produced during
working of the workpiece 2.
[0038]
The criteria for setting such a sintered state may only be
confirmed by accumulated experimentation based on trial and error
for combinations of different workpieces 2 and the support 1.
[0039]
Normally, the shape of the support 1 at each height position
is designed for shaping by a CAN system or CAE system to adapt
the shape and load of the workpiece 2.
[0040]
When the shape is specifically designed using a CAN system
or CAE system, the most suitable shape to adapt the shape and
load of a given workpiece 2 is selected based on previously
accumulated data.
However, when the shape at different heights is to be
designed adapting a new shape and load of a workpiece 2, the
nearest data and the shape of the support 1 at different heights
corresponding to those data are selected from the previously
accumulated data of workpiece 2 shape and load, and a program
is employed that corrects the dimensions of the shape at different
height positions selected as described above, based on
proportional distribution using the proportion between the two
sets of data, to allow further automatic design.
An embodiment may of course be employed in which the notch
11 shown in Fig. 1(a) is also designed by a CAN system or CAE
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system.
[0041]
With basic construction (2) using a CAM and CAE system,
therefore, it is possible to very efficiently shape the support
1.
[0042]
Similar to the requirement for selection of the material
composing the workpiece 2 to adapt the function of the workpiece
2, a suitable material is also preferably selected for the support
1 as well, for support of the workpiece 2.
[0043]
In basic construction (2) , an appropriate material may be
selected to adapt the thickness of the support 1 and the direction
at each height position.
[0044]
The support 1 and workpiece 2 will naturally differ in the
properties of the necessary materials.
That is, since the strength required per unit volume is
lower for the support 1 than for the workpiece 2, an embodiment
may be employed in which the degree of sintering of the support
1 is lower than the degree of sintering of the workpiece 2.
[0045]
A specific method for obtaining different degrees of
sintering for this purpose may be selected from among:
(1) a method of setting the thickness of the support 1 to
be larger than the thickness of the workpiece 2 at each laminating
unit 4,
(2) a method of using the same thickness for the laminating
units 4, and setting the radiation dose of the laser beam or
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electron beam per unit area for the support 1 to be lower than
for the workpiece 2, and
(3) a method of setting the thicknesses of the laminating
units 4 and the radiation dose per unit area to be the same, while
conducting irradiation every several laminating units for the
support 1 and conducting irradiation every single laminating unit
for the workpiece 2.
[0046]
Based on this selection, it is possible to select a
condition for basic construction (2) which does not require as
powerful a degree of sintering for the workpiece 2 as for the
support 1, thereby allowing efficient production to be carried
out.
[0047]
A description will be given below according to Example.
[Example]
[0048]
As a feature of Example, in order to finally achieve the
feature described above, sintering is omitted in some of the
powder layers among the plurality of powder layers formed between
the top end of the support 1 and the bottom end of the workpiece
2.
[0049]
Even if sintering is omitted for some of the powder layers,
the sintering of the other regions may maintain bonding between
the unsintered powder layers, although the degree of bonding is
very minimal compared to that by the actual sintering.
[0050]
As a result, Example also allows easy separation between
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the support 1 and the workpiece 2.
[0051]
The region range for the degree to which sintering of some
of the powder layers may be omitted while still allowing
maintenance of the bonded state between the support 1 and the
workpiece 2 and easy separation, must also be confirmed by
accumulated experimentation based on trial and error.
[Industrial Applicability]
[0052]
Thus, the present invention achieves both the necessary
strength and low economic cost for a support that supports a
workpiece, while also creating efficient production conditions
for both workpieces and supports, and it is therefore of
tremendous value in the field of machine tools.
[Reference Signs List]
[0053]
1: Support
11: Notch
14: Flat surface or curved surface
2: Workpiece
3: Container
4: Laminating unit by powder layer
5: Laser beam or electron beam supply
6: Scanner
7: Powder supply tool
8: Squeegee
9: Table
10: Controller
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