WO1991012957A1

WO1991012957A1 - A device for manufacturing three-dimensional objects

Info

Publication number: WO1991012957A1
Application number: PCT/SE1990/000136
Authority: WO
Inventors: Larsson Ralf; Larsson Ove
Original assignee: Sparx Ab
Priority date: 1990-02-28
Filing date: 1990-02-28
Publication date: 1991-09-05
Also published as: EP0518858A1

Abstract

Device for manufacturing of three-dimensional objects, of a substantially homogeneous material by means of a converting machine (1), which is controllable by means of computer instructions. The material, which is constituted by web, sheet or disc shaped sections (16), is insertable in said converting machine, where every separate section is provided to be subjected to a material cutting treatment in accordance to given computer instructions. The separate converted sections are arranged to be brought together and integrated with each other in a programmed sequence. The converting machine (1) comprises at least one means (57) for annihilation or connection of material particles in the material section (16) in the form of at least one electrode of a spark converting machine, glow pen, plasma cutter or the like, which means and/or which section is controllable by means of computer instructions in the x- and/or y-direction of the section plane.

Description

A DEVICE FOR MANUFACTURING THREE-DIMENSIONAL OBJECTS

The invention refers to a device for manufacturing of three- dimensional objects, of a substantially homogenous material by means of a converting machine, which is controllable by means of computer instructions, and which material, which is constituted by web, sheet or disc shaped sections, is inser- table in said converting machine, where every separate section is provided to be subjected to a material cutting treatment in accordance to given computer instructions, whereby the converted, separated sections are arranged to be brought together and integrated with each other in a pro¬ grammed sequence.

BACKGROUND OF THE INVENTION

At design work its desirable to be able to visualize and sometimes also physically present the three-dimensional geometries of the structural detail in question. This appli- es in particular to work with computer aided design (CAD), where the data bases often are used directly without human interference for manufacturing purposes (CA ). The costs of errors in connection with machining in numerically control¬ led converting machines and other automatic manufacturing machines because of design errors are high.

At complex three-dimensional geometries, e.g. cylinder heads of internal combustion machines, and at mounting of several cooperating components which are difficult to survey, e.g. at lay-out work in the motor compartment of a passenger car, the availability of physical models early in the design process, often is a requirement for the design work to be carried out.

Larger companies, e.g. car industries, which often are confronted with this need, often have pattern shops of their own, where details are produced, on demand of the designer, in materials which are realatively simple to machine or form.

Certain industries also use CAD- data bases for producing models in e.g. NC - cutters. Small industries engage ex- ternal pattern shops or in certain cases completely elimina¬ te this step in the product developing work, with high cassation costs as a result.

What is common to all for the present used modell production methods is however the time consuming ordering and produc¬ tion work, which forces the designer to discontinuity in his or her actual assignment, that is to finish and approve the production basis for the final product or component.

Thus it is desirable, if possible, to offer the designer a more direct perception of his object so that an interactive process can be achieved between the creativity of the desig¬ ner and his or her results without time consuming delivery periods.

One way to achieve a certain feeling of the three-dimensio¬ nal goemetry of the object is applied by certain CAD- sup¬ pliers, where the system permits the designer to observe the object from an optitional angle of sight on the display and thereby experience a photo-like perspective picture of the detail. Large efforts have been carried out by suppliers, in the object of increasing the realism in this type of presen¬ tation, e.g. by means of colouring and shade effects. In practice however it has shown that this type of aid is more advantageous at selling and aesthetic presentations, than that they actively contribute to a reduced need for purely physical models, in the the design work per se. A method to manufacture physical models by means of CAD data bases in direct connection to the work place of the designer is described in US 4,575,330 (C.W Hull). This so called stereolithographic method, which is based on the principle that a UV - radiating focussed light cross-links and thereby cures the impact point on the surface layer of a flowing photopolymer. The light source which is two- dimensionally controllable, above the bath with the UV- curing plastic solution, then can be made to cure a section of the desired model. The section thus produced, is deposited on a table which is movable in the depth direction of the bath. By successively sinking the table after every completed trans¬ versal section, every layer can be bound to each other and a complete model of the object can be produced. This method, which for reasons of time only should produce scale models, until now only has been tested in small machines with a capcity of some cubic decimeters. The accuracy to size has been stated to be a problem as a result of shrinking and internal tensions, which cause distorsions in the complete model. The high purchase cost of the equipment and relative¬ ly time consuming process for model manufacturing, in a number of hours per model, are factors which limit the use of the method.

To sum up it may be stated, that there is still a lack of effective and practical aid in product developing work for interactive model manufacturing in immediate connection to the work place of the designer.

THE OBJECT OF THE INVENTION AND MOST ESSENTIAL FEATURES

The object of the invention is to create a device which makes possible interactive manufacturing of three- dimen¬ sional models, which substantially corresponds to the CAD- data base which the operator intends to reproduce. In that way the device should make a rapid manufacturing of the actual object possible, without human interference after the operator by way of his terminal has ordered the manufacture of one or several models. This device should be possible to place in office environ¬ ment and produce complex three- dimensional models, which in a digital way reproduces the object defined in the data base, and this has been achieved by the converting machine comprising at least one means for annihiliation of material particles in the section in the form at least one electrode to a spark converting machine, glow pen or the like, which means and/ or which section by means computer instructions is controllable in the x-and/or y- direction of the section plane.

DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a typical user situation where a device accor¬ ding to the invention makes inter active manufacturing of models possible, at terminal work. Fig. 2 shows diagrammatically and in perspective view a device with movable converting tool according to the in¬ vention.

Fig. 3 shows the device in fig. 2 seen from the side. The working position of the converting tool moreover is enlarged - the encircled portion - for the purpose of showing details more clearly.

Fig. 4 shows another device with fixed electrode matrix in side view. The working position of the working tool moreover is enlarged - the encircled portion - for the purpose of showing details more clearly. Fig. 5 shows in perspective how a flat bed plotter can be provided with an accessory, which can machine sheets or discs according to the invention.

Fig. 6 shows a lateral view of a modified device according to the invention with a single line spark electrode cam. The encircled portion shows an enlargement of certain details. Fig. 7 shows the device according to the fig.6 from the top side.

Fig. 8 shows in perspective a design variant with a single line electrode cam applied on web formed materials. Fig. 9 shows a schematic side view of the device according to fig. 8. Fig. 10 shows a further modified device according to the invention applied on sheet or disc formed materials.

LIST OF THE REFERENCE DESIGNATIONS

In the drawings, which show embodiments of devices for performing the method the reference designations are:

1. A complete device for manufacturing of models according to the invention. 2. A terminal connected to CAD -computer or the like.

3. A model manufactured according to the invention.

16. A sheet, web or disc formed section of a material of which the model is manufactured.

18. A spark or arc. 25. A cavity caused by the machining, where material has been removed, e.g. melted or vaporized, from the material disc.

28. A store e.g. a roll with unmachined material sections.

29. A servo device controlled in x- and y-direction for displacement of the machining tool in two independent direc¬ tions parallel to the material disc.

30. Guide rim, e.g. a rack, for control and operation of the servo device.

31. A model, produced with a device according to the in- vention, during construction.

32. A assembly plate for fixation, e.g. through vacuum of the first ready-machined disc section of a model.

33. An operation and control device for translating movement of the not complete model, called stamp. 34. A fixed foundation relatively the counter stay plate.

35. A cable for energy supply.

36. A machining tool, e.g. a spark electrode or laser gun, called tool.

37. A counter stay plate which is not influenced by the machining process.

38. A cavity created in the material section during the converting process. 39. A store for collecting of disc material remains after complete machining, e.g. a material roll.

40. A cable for connection between the slip contact and the current supply of the device. 41. A slip contact for galvanic contact to the foil layer of the material section.

42. A spark electrode, plasma cutter or the like.

43. An electrically conducting layer, graphite or metal foil, substantially covering the whole of one of the materi- al section sides, called foil layer.

44. A logic and /or power supplying unit, which distributes necessary voltages to present spark electrodes in accordance to control data from the control unit, called drive circuit.

45. A cable for serial communication and energy supply between and control unit and/or current supply unit.

46. A flat bed plotter.

47. An assembly which supplies the machining tool with necessary energy.

48. A resilient device which preloads the store with not joined material sections against gussets.

49. A store for unmachined material sections.

50. A pile with unmachined and not joined material sections.

51. A servo controlled movable unit for moving of a single line spark electrode cam and e.g. an IR-valve in a direction parallel to the material section.

52. A gusset which positions an unmachined material section.

53. A heat radiating element, e.g. an IR-valve.

54. A waste substance which surrounds a ready-machined material section. 55. A layer of a glue substance, e.g. melting glue.

56. A single line spark electrode cam.

57. Means for machining of material.

58. Unit for joining of machined material discs.

59. Conveyor. 60. House with a vacuum source to the counter stay plate. 61. Guide. According to a first embodiment of the invention, shown in fig. 2, a machining tool 36 is movable in two directions (arrow C and D along a counter stay plate 37. Unmachined material sections 16 eg. in the form of a continous web 16, is fed stepwise ahead from a roll 28 (in the direction of the arrow A) to a position behind the counter stay plate 37, seen from the tool 36, and clamped to this eg. by means of vacuum. The control unit not shown, starts the tool 36 and conveys this along x and y coordinates by means of a servo unit 29 in a path 25, corresponding to eg. the outer con- tours of the present section in the present object, by means of data from the CAD-system. The tool 36 then is able to either separate material, eg. through melting or vaporiza¬ tion, or by joining of the material, eg. through thermal setting or sintering, of material particles, which are loosely interconnected by a soluable glue or the like to a material section, which substantially reproduces the present form in the present object.

After completed machining, an assembly plate 32 with attac- hed material sections, which are going to form the completed model 31, is fed forward to fit - up towards the latest material section (arrow B). Thus this complete material section will be pressed between the extreme and the last mounted material section on the counter stay plate 37. By eg. supplying heat from the counter stay plate 37 with internal resistance heating, a melt glue on the last comple¬ ted disc section, can be made to join this disc section to the earlier produced pile of disc sections 31.

Thus it is possible, disc for disc to machine and join a model, which reproduces the geometries of the CAD- data base. After completed joining, the ready model can be relea¬ sed from the device, eg. by stopping the vacuum between the model and assembly plate 32.

Fig. 3 shows machining by cutting by means of a light arc 18 caused by a flash over between a spark electrode 42 in the tool 36 and an electrically conducting foil layer 43 on the back side of the material disc 16. The counter stay plate 37 hereby should show an optimized electric and thermal resis¬ tance, so that the light arc is not disturbed or in other way is affected negatively. The energy supplied in the light arc 18 and the moving velocity of the control device 29 thereby will affect the geometry of the cavity 25.

A sliding contact 41 connected to eg. electrical earth by the cable 40 makes it possible to create an electrically closed system between the foil layer 43 and the spark elec¬ trode 42.

Another device for thermal machining of the material discs is shown in fig. 4. In this embodiment servo-device has been replaced with an electrode matrix which is fixed relatively the material disc 16, or gate of conducting points 42, eg. spark electrodes, which are sequentially supplied with con¬ trol data from the control unit (not shown) in the cable 45 by series parallel converting drive circuits 44. In this embodiment the electrode matrix also operates as a counter stay plate.

Still another embodiment is shown in Fig. 5, where a simple accessory makes it possible to use a common flat bed plotter 46 as a machining apparatus according to the invention. In this variant the pen in the penholder of the plotter 46 is replaced by a machining tool 36. This tool can e.g. be a spark electrode, from which an arc emanates or a hot tip electrode. The energy to the machining tool is supplied through the cable 35 from a power supply 47.

The embodiment in fig. 6 and 7 operates with a movable cam of spark electrodes 56. This cam 56 can be guided by the servo device 51 just above the surface of an unmachined material disc 16. Every material disc 16 which is not joined with any other material disc before its machining, is pro¬ vided partly with a conducting layer 43 and a thermally actuatable layer of e.g. meltable glue 55 on that side of the material disc which is faced off the spark electrodes 42. These layers 43 and 55 preferably may be integrated in one and the same layer, e.g. a conducting meltable glue layer.

During the time when the servo unit 51 brings the electrode cam 56 ahead, the control unit (not shown) can connect present spark electrodes 42 in accordance to the geometries of the present section, so that sparks occur between the spark electrodes 42 actuated in this way and through the conducting layer 43 connected to a suitably formed earthing device (not shown). In this way it is possible, at a very high velocity to permanently remove desired material por- tions 25 from the material disc 16. In this way, the device can machine one disc per scan with the servo unit 51.

The first thus machined disc in every new model after com¬ pleted machining and transport of the electrode cam 56 to a position at the side, seized by an oscillating assembly plate 32, which operates with vacuum. The ready machined material disc thereby can be made to be torn off from the store 49 out of four corner plates 52. When the assembly plate 32 and the material disc retained thereon has returned to the original position, the servo can again start and drive the electrode cam 56 over the following material disc, which has been pressed into position towards the four corner plates 52, when the former disc was torn off. The maching thereafter can be repeated. A heat radiating unit 53 mounted on the servo unit 51 simultaneously with the machining being carried out or separately heat a melting glue 55 applied on the backside on the former machined disc.

When thus the machining on the disc is completed, the glue on the disc number 1 also will be melted and ready for joining with disc number 2. This is carried out by the assembly plate 32 once again makes an oscillating movement, so that disc number 1 has time to be pressed long time enough against the disc number 2 for the melting glue to join the discs. When the assembly plate returns to its original position, disc number 2 will be torn off from the four corner plates 52 of the store.

The device according to fig. 6 and 7 thereafter with a very high velocity repeat this sequence, whereby a new material disc 16 is supplied to the prospective model 31 for every scan with the electrode cam 56 and the assembly plate 32.

When the model is completed, the vacuum force between the model and the assembly plate may cease, whereby the comple¬ ted model along with surrounding waste material is released from the device.

At this embodiment and other described herein, when the surrounding waste material 54 accompanies the completed model 31, the operator manually has to remove the surroun¬ ding waste material 54, which preferably is slightly attac- hed to the model in smaller material sections placed out by the control unit of the device.

Still an embodiment is shown in the figures 8 and 9, which differs from that shown in fig. 2, by the machining means 57 being constituted by a bar, . also called electrode cam, extends over substantially over the complete width of the web. The electrode cam is placed on one side of the material web and cooperates with a counter electrode on the other side of the web. This counter electrode can be an electrode plate, electrode cam, electrode wire or electrode roller extending over the total width of the web but can also be an electrically conducting foil on the back side of the materi¬ al web. Instead of a common counter electrode this may consist of a cam electrode where every related electrode pair is connected to each a transformer coil.

The details cut out by the machining means 57, which are going to form the new model, are transported by means of a conveyor 59 to an assembly plate 32, where the material sections are piled on each other. The cut out details are attached to the conveyor 59 by means of vacuum or magnetic forces. During the transport from the material web to the piling station the cut out details 31 are submitted to a heat treating to actuate a melt glue or they pass a glue station where an adhesive means is applied so that every single detail is connected to the preceeding detail. If the electrode pins of the cam electrode 42 are constituted by electrodes of a plasma cutter the counter electrode may be constituted by the material web as such or an electrically conducting layer applied on this.

The first cut out material section 16 will be glued to the assembly plate 32, which can be heated so that the first machined glued material section can be loosened from the plate.

A further modified embodiment is shown in fig. 10 where the material sections may consist of single sheets or discs, which in a known manner are fed down towards a counter stay plate 37, which has porous structure so that the surrounding air can pass through the plate. The counter stay plate 37 is placed in a box 60 in which can be provided a negative pressure and which brings the material section to fit-up against the plate. The counter stay plate is movable along a guide 61, so that the material section 16 can be brought to take different operational positions, just in front of the machining means 57 in a first step, to a heat radiating element in a second step and to the integration unit with the assembly plate 32, where the joining of the separate segments takes place in a third step.

The advantage of using a porous back side electrode when using a spark elektrode as machining means 57, is that the vacuum which is provided to clamp the material section 16 also contributes to enhance the cutting velocity, since the vacuum also removes by suction the ionized air which is formed in the spark between the electrodes.

The invention is not limited to examples on devices and materials described herein, but a several variants and combinations are possible within the scope of the invention. Thus it is possible to make devices with fixed needle formed electrodes, which penetrate into materials and thereby provide a partial vaporization or melting. It is also pos¬ sible to use materials of easily fusible homogenous or sintered alloys. The waste material after the machining can be removed by means of mechanical oscillation energy e.g. focussed ultrasound.

Hereby very rapidly without human intervention accurate three-dimensional models can be manufactured and objects in a device or machine which can be placed in a common office environment. The equipment and material can be marketed at relatively low costs and thereby the method can give an opportunity for many designers of structure or form and architects, to have direct access to a model at their place of work.

Claims

1. Device for manufacturing of three-dimensional objects, of a substantially homogenous material by means of a con- verting machine (1), which is controllable by means of computer instructions, and which material, which is consti¬ tuted by web, sheet or disc shaped sections (16), is inser- table in said converting machine, where every separate section is provided to be subjected to a material cutting treatment in accordance to given computer instructions, whereby the converted, separated sections are arranged to be brought together and integrated with each other in a pro¬ grammed sequence, c h a r a c t e r i z e d t h e r e i n, that the converting machine (1) comprises at least one means (57) for annihiliation or connection of material particles in the material section (16) in the form of at least one electrode of a spark converting machine, glow pen, plasma cutter or the like, which means and/or which section is controllable by means of computer instructions in the x- and/or y-direction of the section plane.

2. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the material in the section (16) is constituted by a cell structure, e.g. in the form of a foamed plastic materi¬ al, preferably of polystyrene.

3. Device according to claim 2, c h a r a c t e r i z e d t h e r e i n, that the plastic material in the section (16) contains elecrtically conducting additive, which gives the plastic material an electric breakdown resistance corresponding to about the breakdown resistance of the surrounding medium, which e.g. can be constituted by air, and that the additive preferably is constituted by or contains < 20% carbon pow¬ der, preferably 5 - 10%.

4. Device according to claim 2, c h a r a c t e r i z e d t h e r e i n, that the material in the section (16) contains at least one substance which forms or releases a protective gas at the machining.

5. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the material in the section (16) has a fluid permeable structure so that the surrounding medium can pass through the section.

6. Device according to claim 5, c h a r a c t e r i z e d t h e r e i n, that one of the electrodes is constituted by the material section (16), preferably manufactured from a metal strip, metal sheet or the like.

7. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the material section (16) on one side is covered by an electrically conducting layer (43) which forms a plate electrode, and on the other side with an adhesive coating, which may be activated after a passed change of state ( e.g. by thermal activation).

8. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the material section (16) on one side is coated with an electrically conducting melt glue coating which may be reactivated.

9. Device according to claim 1 , c h a r a c t e r i z e d t h e r e i n, that the structure of the section material is constituted by dissolvably joined particles , e.g. of a ceramic material, of which certain at the treatment in the converting machine in accordance with given computer instructions are perma¬ nently connectable with each other, while untreated par¬ ticles, preferably by means of a solvent or a dissolving method, e.g. by means of concentrated mechanical oscillation energy ( focussed ultrasound), are separable from the perma¬ nently connected particles.

10. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the means (57) comprises at least two electrodes on each side of the section (16) for annihilation or connection of material particles in the section (16).

11. Device according to claim 10, c h a r a c t e r i z e d t h e r e i n, that the means (57) is constituted by at least one elec¬ trode, which is movable over substantially the whole section area, e.g. a spark electrode (36) on one side of the section (16) and one electrode plate, roller, foil or the like extending over substantially the whole area of the section on its other side.

12. Device according to claim 10, c h a r a c t e r i z e d t h e r e i n, that the means (57) is constituted by at least one bar (42) extending over substantially the whole section provided with a number of electrode rods (42a), placed in at least one line along the bar, on one side of the section and of one electrode plate (43), electrode roller, electrode foil or the like on the other side.

13. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the material section (16) on one side is coated with an electrically conducting layer (43) forming a plate elec¬ trode, preferably designed as a strippable foil, which is intended to protect an adhesive substance positioned between the material section (16) and the foil (43).

14. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the counter stay plate (37) of the converting machine (1) is formed as a vacuum plate, which is provided to clamp the material section (16) by means of vacuum, and to evacua¬ te the medium which surrounds the machining means (57) .

15. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the means (57) is constituted by at least one elec- tyrode , which is movable substantially the whole section width, e.g. a plasma, spark or hot wire electrode (36).

16. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the machining means (57) are designed to form also a counter stay plate.

17. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n, that the cut out material sections (16) by means attraction forces acting through the conveyor (59), said forces being vacuum or magnetic, fix the sections (16) to the conveyor during the transport.