DE102011119735A1 - Wire having increased bending stiffness useful as a plastic-welding wire, comprises wire segments connected together in a buckling-resistant manner - Google Patents

Abstract

Wire comprises wire segments, which are connected together in a buckling-resistant manner, where the wire has an increased bending stiffness or whose buckling strength is restored after a fracture.

Description

Wires of melting materials for 3D printers using the FDM process are pushed into the heating chamber of the print head via a feed channel.

In this case, only such wires can be inserted, which have a sufficient rigidity.

Through the stiffness of the wire, the viscosity of the melt, and the tightness of the feed channel, pressure is built up inside the melt chamber which drives the hot melt outward through the orifice of the nozzle.

Insufficient stiff wires can not be pushed into the melting chamber, instead they form a bulge or bumps before insertion. ( 7 )

In order to be able to print such soft materials with a 3D printer, it is proposed here to provide soft, elastic materials with a shell that consists of a stiffer material. The stiffer material reduces the tendency of the soft, inner material to bulge, also increases its kink stiffness.

Preferably, similar, miscible polymer types are used for inner and outer material. Many types of polymer can be adjusted from the manufacturer so that they are "harder" or "softer" depending on the use or with higher or lower elongation at break.

For example, for "inside" a very soft thermoplastic polyurethane (TPU) with a Shore hardness of A30, for the stabilizing shell material a TPU with a Shore value of D85 or harder. Both materials melt in the melting chamber and mix depending on the ratio of A to B and melt flow to a polymer mixture with, for example, Shore A45. In this case, a meaningful proportion of shell to inner material of preferably 5-20% is expedient. A shell of only 0.1 mm wall thickness is quite capable of conveying a soft inner material of 3.0 mm, without resulting in bulges before the melt chamber feeder. 3D components made of soft materials are z. B. elastic air hoses.

Furthermore, wires are known which would melt very well in an FDM printer, but are so brittle that they do not break the path from stocking the wire on a spool to the melting chamber (longer distances with curves and small radii) survive. Because of this fragility, these wires can not be used unless they are only manually introduced into the melting chamber in the form of straight rods (of limited length). A thin shell around such a brittle wire would avoid the frequency of unwanted fractures, or if that break has occurred, the fragments will continue to stick together. Furthermore, wires are hereby proposed which include powders, liquids or mixtures thereof.

A thin sheath (sleeve) pushed on two ends of a broken wire is also able to feed this broken wire inside the FDM printer again.

If such a repair sleeve made of a material shrinking on heat, so a particularly intimate connection can be achieved.

It turns out that the material of the sleeve should be made of a similar type of plastic as the soul.

Plastic welding wires for welding extruders with which containers are welded or welding tracks are also claimed for this patent application. Description / Legend Fig. 1 Cross-section of a wire with a shell of a stiffer component B (black) and an internal, unstable material B (white) Fig. 1a Cross-section wire, with the outer component infiltrated into the interior. A zone of two components is formed in addition to the envelope, For example, if a prone to brittle fracture component A2 is extruded into a wire, this can be provided in an immersion bath or by painting with an enveloping component B2. Depending on porosity or absorbency, B2 partially or completely penetrates A2. The transition region AB reduces the wall thickness of the layer B2 necessary for increasing the stability / buckling resistance. Fig. 2 round, slightly oval cross section, stiffer component B (black) as inlaid strip Fig. 3 round, slightly oval cross-section, stiffer component B (black) than two inlaid stripes Fig. 4 oval base section with a flat side, stiffer component B (black) than two strips, Fig. 5 outer, stiffer component B in the form of 8 wires wound around A in a spiral manner Fig. 6 component B arranged on the pointed sides of an oval Fig. 7 Wire feed with two knurled feed rollers. The pushed conventional, soft / unstable wire bulges even before the feed channel of the heating chamber due to insufficient rigidity, or he tends to buckling. Fig. 8 Wire with filling of a broken, brittle material, wherein the brittle material A1 is provided in the unbroken state with the sheath B, to be broken regularly in an optional subsequent step. The envelope B holds the material together and eligible. The packing density of A1 is significantly higher than, for example, a powdery material with a large proportion of pores. Fig. 9 Wire with powdery filling A3. Due to the high pore volume in the wire, the created 3D object will have a porosity similar to a closed-cell foam, because the air in the pores can escape only to a limited extent during the extrusion through the melting chamber. The powder filled wire may have tapers to segment and stabilize the position of the powder, which segments the cavity in the wire. The filling may also be an actinic substance, for example an actinic liquid which is mixed with a powder of a preferably already cured actinic substance. The viscosity of the actinic liquid is thereby increased. It acts as a kind of binder of powder when activated. Fig. 10 Two ends of a wire are connected to a push-on sleeve (M). Made of shrinking materials, this can also be shrunk and results in a more stable connection. Fig. 11 Here are two ends of a wire filled with a powder. The sleeve M1 is designed as a double cap. Possibly. also made of shrinking material. Fig. 12 The connection of two wire ends takes place here by a hose segment (clip) M3, which is clamped. Fig. 13 The wire ends are tapered here. The pieces of wire can be connected together without increasing the overall diameter. A softer component A1 brittle component that shows cracks across the entire material that it is consistently broken and is stabilized by B. A2 a component prone to brittle fracture A3 Wire with powdery filling FROM Transition area B stabilizing component B1 Stabilizing component that has constrictions at recurring points B2 stabilizing component that penetrates into the inner material M slide-on sleeve M1 Sleeve designed as a double cap, for stabilizing wires with loose or liquid content. M2 The sleeve is internally equipped with a second layer, preferably an adhesive layer. D unspecified wire, after break connected by sleeve with other piece of wire K adhesive layer

Claims (10)

Wire, characterized in that a) has an increased buckling resistance or b) its kink resistance is restored after a break or c) wire segments are preferably connected to each other kink-resistant. Wire according to claim 1, characterized in that this a) melts in a temperature range of 50-350 ° Celsius and b) preferably for a molding printing method z. B. by the FDM method or c) is used as a plastic welding wire. Wire according to claims 1-2, characterized in that this consists of an array of at least two materials, one material over the other either over part of its length or over its entire extent a) wrapped or b) the materials are stacked next to each other, c) one material is wrapped or looped around the other, or d) one material runs in strands along the axis of the other or is embedded in this. Wire according to claim 1-3, characterized in that it consists of a soft component (wK), preferably an elastomer and at least one stiffer, stabilizing component (sK), wherein a) wK preferably consists of materials with Shore A0 to D60 b) wK has elongations at break of 10% -2000%, c) sK consists of materials larger than Shore D 45 d) sk consists of materials with elongations at break of less than 50%, preferably less than 10%. Wire according to claims 1-4, characterized in that it consists of a brittle, preferably inner component (iK) and at least one stiffer, stabilizing, preferably outer component (k), wherein a) iK has elongations at break of less than 10%, preferably less than 1%, and b) iK is still enveloped in the fractured state by αK. Wire according to claims 1-5, characterized in that a) its components either of materials of different plastic groups, for example. The inner component of soft polyurethane (PU) and ÄK of tensile ABS b) or consist of the same plastic groups, eg. iK of PU and ÄK of PU c) or mixed together and melted to form new polymers. Wire according to claims 1-6, characterized in that a preferably inner component a) is a loose powder, preferably with a grain size of less than 0.35 mm, b) a powder bound with a binder, c) a powder mixture, d) or a mixture of a solid powder with a gel or a liquid e) a liquid, a gel or wax or f) an actinic substance, preferably a liquid or gel-like photopolymer or g) an actinic substance 5.f, mixed with a powder, preferably from an already cured actinic substance. A wire according to claims 1-7, characterized in that it has constrictions / tapers along its extension in the direction of the longitudinal axis, the walls being at the points of constriction a) touch each other, b) are interconnected or c) do not touch each other. Wire according to claims 1-8, characterized in that an outer component is applied to the inner component, wherein the preferably liquid or heated applied outer component infiltrates the inner component. Wire according to claims 1-9, characterized in that an outer component, preferably in the form of a connecting piece, for. As a sleeve or a hose segment, is pushed onto the ends of two pieces of wire to connect them.

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