Apparatus and corresponding method for laser welding

Abstract

The present invention relates to an apparatus for laser welding internal workpieces 21, 121, 221, 321, 421 of a medical device, such as a catheter, to external workpieces 22, 122, 222, 322, 422 in a welding area, wherein the internal workpieces 21, 121, 221, 321, 421 and the external workpieces 22, 122, 222, 322, 422 have a longitudinal axis 25, and the apparatus comprises a bearing device 10 comprising bearing elements 11, 111, which are configured to apply pressure to the external workpieces 22, 122, 222, 322, 422. Furthermore, the apparatus comprises a laser device 5 that emits electromagnetic radiation for welding, which is configured so that the emitted electromagnetic radiation is directed through the bearing elements 11, 111 to the welding area.

Description

【Technical Field】 【0001】 The present invention relates to the manufacture of medical devices, and more particularly to laser welding two workpieces (also called shafts or sleeves) of such medical devices, such as catheters, together at at least one part, wherein one of these workpieces (the inner workpiece) extends at least partially into or under the other workpiece (the outer workpiece). The present invention relates to an apparatus for laser welding an inner workpiece of a medical device to an outer workpiece, a corresponding method, and a catheter assembly manufactured by such a method. 【Background Art】 【0002】 Catheters, which house two workpieces or shafts within each other, are widely used in patient treatment. For example, in the procedure of percutaneous transluminal coronary angioplasty (PTCA), an expandable catheter with a balloon distal to the end is used to expand a lesion in the patient's vascular system and open a vascular passage by expanding the balloon with an expansion fluid once or multiple times at an appropriate pressure to a predetermined size and pressing the narrowed area against the arterial wall. In other cases, balloon catheters can be used to expand stents in the patient's vascular system by balloon inflation. Balloon catheters are also used in the treatment of other luminal systems throughout the body. Furthermore, other catheters or medical devices such as endoscopes, or inlet and outlet elements or cable insulators of medical devices, are equipped with tubular piping, where, since laser welding is easily automated, an inner workpiece, such as an inner tube, can be connected to an outer workpiece, such as an outer tube, by laser welding at least in one portion. With respect to such medical devices, for example, the pushability, conformability, and flexibility of the whole device or a part thereof can be adjusted to provide a medical device with characteristics suitable for a particular use of the device. In addition, since a predetermined pressure is applied to the expansion fluid flowing through the tubing of the balloon catheter, for example, the part where one workpiece is fixed to the other workpiece should provide a reliable connection / fixation to ensure the proper functioning of the medical device. 【0003】 Regarding balloon catheters as an example of a medical device, the connection between the distal balloon shaft and the inner shaft, or between the proximal balloon shaft and the outer shaft, has traditionally been performed using heat-shrinkable layers or heat-shrinkable tubing as additional materials and elements. An external heat source, such as a heating jaw or long-wavelength laser beam, heats the shrinkable layer or tubing, thereby shrinking it and applying contact pressure and heat to the shafts to be connected. As a result, each balloon shaft is joined to the inner / outer shaft. However, this known method is complex and costly because it requires heat-shrinkable layers or heat-shrinkable tubing as additional materials and elements in the joining process. This heat-shrinkable layer or tubing must be positioned axially, covering the parts to be connected, before the joining step. Since there is usually a gap between the shrinkable layer or tubing and the diameter of the corresponding balloon shaft, the shrinkable layer or tubing needs to be repositioned just before the joining step begins. The shrinkable layer or tubing is then removed or peeled off, which is a manual process requiring considerable experience. The final step cannot be automated. Another drawback of the known method is that the shrinkage workpiece is typically longer than the portion where the balloon and shaft are connected. Therefore, unintended contact pressure and heat may be applied to adjacent areas of the balloon and / or catheter shaft that are not intended to be part of the connection area. This can result in unintended migration effects in these areas. 【0004】 Another challenge was balancing the labor / cost of manufacturing with often conflicting properties such as the strength and flexibility of the workpiece. Another challenge was providing a flexible transition that improved the operability of the medical device while ensuring sufficient strength at the transition joint. Twisting is also a known problem with over-the-wire (OTW) catheters. Therefore, there remains a need for medical devices with workpieces that reduce manufacturing labor / cost, avoid the aforementioned unintended effects on the balloon and catheter shaft, and simultaneously offer an improved combination of properties such as strength and flexibility. There is also a need for medical device tubing that improves conformability to more easily pass through winding biological structures such as distal coronary arteries and nerve arteries, while maintaining the ability to be withdrawn from such structures. [Overview of the Initiative] 【0005】 The above problems are solved by an apparatus for laser welding having the features of claim 1, a method for joining an internal workpiece of a medical device to an external workpiece having the features of claim 8, and a catheter assembly having the features of claim 15. 【0006】 In particular, a device for laser welding, also known as laser beam welding, of an internal workpiece of a medical device, such as a catheter, to an external workpiece in a welding area comprises a bearing device and a laser device that emits electromagnetic radiation for welding. The internal and external workpieces have longitudinal axes. The bearing device comprises a bearing element, which is configured to apply pressure to the external workpiece. Furthermore, the laser device is configured so that the emitted electromagnetic radiation is directed through the bearing element to the welding area. 【0007】 In one embodiment, the internal workpiece may be a tube, an internal shaft, or the external shaft of a balloon catheter, and / or the external workpiece may be a tube, or the distal or proximal shaft portion of the balloon of a balloon catheter. In particular, in one embodiment, the distal portion of the internal shaft and the distal balloon shaft of the balloon or the distal portion of the external shaft and the proximal balloon shaft of the balloon can be connected by laser welding using the apparatus and the method described below. The balloon may comprise a distal balloon shaft, a distal cone, an action portion, a proximal cone, and a proximal balloon shaft in this order, and in the inflated / expanded state, the diameter is largest at the central action portion and smallest at the distal and proximal balloon shafts. The internal and external shafts may comprise or be composed of at least one thermoplastic material, preferably at least one thermoplastic material from the group of materials including PA, PEBAX, PET, PC, POM, PEI, ABS, PEEK, PPS, PE, and PP. The balloon may include or be composed of at least one thermoplastic material, particularly at least one thermoplastic material from the group of materials including PA, PEBAX, PET, PC, POM, PEI, ABS, PEEK, PPS, PE, and PP. In the assembly of the medical device, the inner workpiece and the outer workpiece may be housed concentrically or non-concentrically but with longitudinal axes parallel to each other. The diameter of the inner workpiece may be 0.1 to 100 mm, preferably 0.3 to 10 mm, the diameter of the outer workpiece may be 0.1 to 100 mm, preferably 0.3 to 10 mm, the wall thickness of the inner workpiece may be 0.01 to 100 mm, preferably 0.01 to 5 mm, and the wall thickness of the outer workpiece may be 0.01 to 50 mm, preferably 0.01 to 5 mm. The diameter of the inner workpiece, the wall thickness of the inner workpiece, and the diameter of the outer workpiece must be selected so that the inner workpiece can be housed within the outer workpiece. 【0008】 This apparatus can accommodate an assembly comprising internal and external workpieces of a medical device during laser welding, and can enable relative motion between the assembly and the bearing device, particularly between the assembly and the bearing elements. For this purpose, the bearing device and / or bearing elements may be configured to be movable along the longitudinal axis and / or rotatable about the longitudinal axis. Alternatively, or in addition to this, the apparatus may include a stand configured to hold the assembly, move the assembly along the longitudinal axis, and / or rotate the assembly about the longitudinal axis. Before welding and accommodating the assembly, the internal and external workpieces may be pre-assembled, for example, by at least one bonding point, welding spot, or locally clamping. For example, the distal portion of the internal shaft and the distal shaft portion of the balloon, or the distal portion of the external shaft and the proximal shaft portion of the balloon, are prepared and pre-assembled for laser welding. The welding area is typically formed by the respective longitudinal portions of each workpiece to be connected. When assembled in advance, the corresponding longitudinal portion of the outer workpiece is positioned on top of the corresponding longitudinal portion of the inner workpiece, for example, by clearance fitting; in other words, the corresponding longitudinal portion of the outer workpiece surrounds the corresponding longitudinal portion of the inner workpiece, and both portions provide a welding area. 【0009】 The bearing element comprises a sphere, a cylinder, or an element having at least a partially spherical and / or cylindrical outer shape, and can allow rotation of the outer workpiece and / or the bearing element about its longitudinal axis, and / or movement of the outer workpiece and / or the bearing element along its longitudinal axis, while applying pressure to the outer workpiece by the bearing element. According to this feature, the bearing element functions as a low-friction sliding bearing. 【0010】 The apparatus may include a motor connected to a bearing element and configured to drive the bearing element toward its longitudinal axis to apply pressure to the outer workpiece. Alternatively, the apparatus may include an airflow or compressed air generator configured to generate compressed air, move the bearing element toward its longitudinal axis, and direct the compressed air toward the bearing element to apply pressure to the outer workpiece. The pressure applied may be small, such that the bearing element makes slight contact with the outer shell surface of the outer workpiece in the weld area. Applying pressure reduces air pockets and creates strong intermolecular bonds within the weld joint between the inner and outer workpieces. Applying pressure improves the weld joint between the outer and inner workpieces and allows for textured application to the outer shell surface of the outer workpiece. 【0011】 A laser device may comprise a laser beam generating unit (i.e., a radiation source) that generates a laser beam at a predetermined wavelength, power level, and time frame (continuous wave or pulsed mode); a laser beam generation unit that generates the laser beam; and an optical unit that directs the laser beam generated by the laser beam generating unit towards a predetermined region of an inner workpiece and / or an outer workpiece and / or a central wire (see below) housed within the inner workpiece. The optical unit may comprise at least one optical element from the group including lenses, filters, mirrors, prisms, diffraction gratings, and apertures. The laser beam emitted from the laser device is fed by a bearing element and thereby directed towards the predetermined region. Therefore, the material of this bearing element, which includes or is composed of at least one material from the group including quartz glass, sapphire, ruby, spinel, and cubic zirconium oxide, is transparent to the predetermined wavelength of the laser beam. In one embodiment, the electromagnetic emission of the laser beam has a wavelength of 0.5 μm to 15 μm, for example, 1.5 μm to 5 μm (near-infrared region). The laser beam generation unit may include a solid-state laser. While the assembly having inner and outer workpieces rotates around the longitudinal axis, and / or while the bearing elements of the bearing device rotate, the laser beam is guided to the assembly through a laser-transparent rotatable element to heat the workpieces to be welded. This allows the contact pressure of the rotatable element to overcome any gaps that may exist between the workpieces, thereby forming the outer contour of the assembly to be welded. In one embodiment, the laser wavelength and / or output may be changed during the rotation of the assembly and / or bearing elements, and / or during the longitudinal movement of the bearing device described below. The laser beam may be focused in a point or linear manner in the welding area, for example, the line extending parallel to the longitudinal axis of the inner and / or outer workpieces. 【0012】 The present invention provides a highly controllable method for laser welding two workpieces, as the heat-affected zone is extremely limited to the contact area and a small area near this contact area on the bearing element that delivers the electromagnetic radiation. The contact area can be determined by the morphology of the bearing element that delivers the laser beam and the pressure applied to the bearing element. Furthermore, the above-described apparatus eliminates the need for additional materials such as heat-shrinkable layers or heat-shrinkable tubes. Thus, the assembly and positioning of such heat-shrinkable layers or tubes, as well as their removal after welding, are unnecessary. Consequently, this apparatus enables the manufacture of medical devices with lower cost and complexity. Moreover, the transition area between the welded and unwelded areas can have a more intricate structure. 【0013】 In some embodiments, the apparatus is used for laser welding an internal workpiece of a medical device to an external workpiece within a welding volume. In this case, the laser device is configured such that the emitted electromagnetic radiation is directed into the welding volume through a bearing element. The welding volume extends within the internal and / or external workpieces along the interface between the internal and external workpieces, i.e., along the welding area. 【0014】 In one embodiment, the bearing device comprises at least one opposing bearing element, each of the bearing element and the group of at least one opposing bearing element comprising an element having a spherical, cylindrical, or at least partially spherical and / or cylindrical outer shape, and the bearing element and at least one opposing bearing element are housed such that an outer workpiece is clamped by the bearing element and at least one opposing bearing element so as to be pivotable around its longitudinal axis. 【0015】 An assembly comprising internal and external workpieces of a medical device is clamped by a bearing element and at least one opposing bearing element so that the assembly is pivotable or rotatable about a longitudinal axis. At least one opposing bearing element is positioned to form an opposing bearing with respect to one bearing element and thus to contact the shell surface of the external workpiece. For example, one opposing bearing element is positioned on the opposite side of the bearing element when the assembly is between the bearing element and the opposing bearing element, or two opposing bearing elements are positioned so that they contact the outer shell surface of the external workpiece on the opposite sides of the bearing element. Preferably, the bearing element and two opposing bearing elements are positioned at an angular interval of 120° with respect to adjacent opposing bearing elements and bearing elements, respectively. Thus, if four rotating elements are used, they are positioned at an angular interval of 90° in contact with the outer shell surface of the external workpiece, and similarly, if n rotating elements are used, the angular interval is 360° / n. When there are two opposing bearing elements, preferably when the diameters of the two opposing bearing elements are smaller than the diameter of the bearing elements, the angular spacing between the two opposing bearing elements may be less than 120°. This angular spacing is based on the longitudinal axis of the inner and / or outer workpiece. 【0016】 As described above, each of the bearing element and at least one opposing bearing element is any composite form comprising, for example, a sphere (also called a ball), a cylinder (also called a roller), or an element having at least partially spherical and / or cylindrical external shapes, such as a cylinder, a sphere, or a cone. In one embodiment, the bearing element and at least one opposing bearing element may have the same or different forms. Thus, the bearing element and at least one opposing bearing element allow for rotation of the outer workpiece around the longitudinal axis, and / or rotation of the bearing element and at least one opposing bearing element, and / or movement of the outer workpiece along the longitudinal axis, and / or movement of the bearing element and at least one opposing bearing element, while the outer workpiece is clamped between the bearing element and at least one opposing bearing element. Thus, the bearing element and at least one opposing bearing element function as a sliding bearing. The diameter of the bearing element and at least one opposing bearing element can be 0.3 mm to 20 mm, for example, 0.5 mm to 10 mm. 【0017】 Therefore, the assembly of the inner and outer workpieces can be held by bearing elements and at least one opposing bearing element forming a bearing device, precisely positioned with respect to a laser beam emitted by a laser device, and moved to form a welded connection between the inner and outer workpieces along most or all of the circumference of the inner workpiece while pivoting under laser radiation to the bearing device. For example, the welded connection may be established over at least 75% of the circumference of the inner workpiece. 【0018】 With a bearing device comprising at least one opposing bearing element, the workpiece is supported by at least one opposing bearing portion of the bearing device, allowing laser welding of low-rigidity outer and inner workpieces. 【0019】 In one embodiment, the bearing device and the laser device are configured to be rotatable about a longitudinal axis. This feature allows circumferential welding to be achieved without rotating the outer and inner workpieces. Alternatively, or in addition to this, the device or bearing device may be configured to rotate the outer and inner workpieces about a longitudinal axis in order to achieve welding along the circumferential direction of the outer and inner workpieces. 【0020】 In further embodiments, each of the bearing element and at least one opposing bearing element is rotatable along an axis parallel to the longitudinal axis of the inner and / or outer workpiece. For example, the bearing element and the opposing bearing element may be rolling bearings or pneumatic bearings. Thus, friction between the outer workpiece and the bearing element and the opposing bearing element can be reduced when the outer workpiece rotates and / or when the bearing element and the opposing bearing element rotate around their longitudinal axes. 【0021】 In one embodiment, the bearing element and at least one of the at least one opposing bearing element are configured to be movable along the radial direction of the inner and / or outer workpiece. This movement of a few millimeters or centimeters may be useful when housing and removing assemblies with inner and outer workpieces before and after welding. The radial movement of at least two rotatable elements can increase the distance between the rotatable elements, thereby facilitating the housing of assemblies into and out of the bearing device. 【0022】 In further embodiments, at least one of the bearing element and / or at least one opposing bearing element is configured to direct airflow towards the welding area. For example, the bearing element and / or at least one opposing bearing element may have an opening for directing airflow towards the welding area. Alternatively, or in addition to this, if the bearing element and / or opposing bearing element are embodied as an air bearing, airflow can be directed towards the welding area from the air bearing itself. 【0023】 In one embodiment, the bearing element and at least one of the at least one opposing bearing element are provided with a contour relief for forming the contour of the outer workpiece shell surface and / or the inner workpiece shell surface. For example, the contour relief includes projections or recesses extending along at least a portion of the circumference of each bearing and / or opposing bearing element, and / or projections or recesses extending along at least a portion of the (longitudinal) axis of each bearing and / or opposing bearing element, where the (longitudinal) axis of each bearing and / or opposing bearing element is parallel to the longitudinal axis of the inner workpiece and / or outer workpiece. The projections or recesses may have any kind of circumferential contour, or, for example, a linear contour extending along the (longitudinal) axis of each rotatable element (e.g., having at least a partially cylindrical shape) parallel to the longitudinal axis of the inner workpiece and / or outer workpiece. Alternatively, the projections may have a helical contour. Therefore, each type of protrusion / recess forms a corresponding groove / protrusion on the shell surface of the outer workpiece, or, where applicable, on the shell surface of the inner workpiece protruding from the outer workpiece, either in place of or in addition to the outer workpiece. The inner workpiece can form a tip portion of a certain distance. For example, grooves extending parallel to the longitudinal direction of the inner and / or outer workpieces can reduce the cross-sectional area of ​​the inner and / or outer workpieces, thereby facilitating insertion into the lesion. Helical notches / grooves can improve flexural flexibility in their respective regions, for example, at the tip portion of the inner workpiece. At the same time, the indentation remains within the same range as in the absence of helical notches. In addition, for some applications, applying rotational motion during insertion into the lesion may facilitate this insertion. For example, if circumferential notches are generated on the outer shell surface of the inner and / or outer workpiece, or directly at the end of the outer workpiece, by at least one projection of the bearing and / or opposing bearing element, the bending flexibility of each part of the inner workpiece (e.g., the part forming the catheter tip) is improved while maintaining good indentation and shape of the inner workpiece (e.g., the tip). Furthermore, the tapered portion of the inner workpiece, which has the thickest wall thickness at the interface with the more robust workpiece, forms a transition region where the mechanical properties seamlessly merge with the properties of the welded area. 【0024】 In one embodiment, the bearing element and at least one opposing bearing element are rotatable about an axis perpendicular to the longitudinal axis of the inner and / or outer workpiece. By rotating the bearing and opposing bearing element in this manner, a weld with a predetermined length along the longitudinal axis of the inner and / or outer workpiece can be generated. Alternatively, or in addition to this, the laser device may be controlled to move the electromagnetic radiation beam along the bearing element that emits the electromagnetic radiation, for example, along the longitudinal axis of the inner and / or outer workpiece. This movement of the beam can cause the weld area to extend along the assembly of the inner and outer workpieces. 【0025】 In one embodiment, the apparatus further comprises a central wire configured to be housed within an inner workpiece. The central wire may be introduced into the inner workpiece before being housed in a bearing device and welded. This allows the inner workpiece to be stabilized, held, and / or moved (rotated), thereby stabilizing, held, and / or moving (rotating) the entire assembly of the inner and outer workpieces. Furthermore, the central wire reflects electromagnetic radiation emitted from the laser, thus aiding in the (uniform) heating of the inner and outer workpieces. Alternatively, or in addition to this, the central wire may absorb at least a portion of the electromagnetic radiation emitted from the laser, which can heat the central wire. Thus, the laser weld joint between the inner and outer workpieces can be improved. The diameter of the central wire may be less than or equal to the inner diameter of the inner workpiece. The central wire may include, or be composed of, a metallic material (e.g., silver, gold, or any alloy thereof), a polymer material, or glass fiber. The surface of the central wire may be configured to increase the reflectivity of the central wire to electromagnetic radiation emitted by the laser. In addition, the surface of the central wire may be configured to increase its absorption rate to electromagnetic radiation emitted by the laser. 【0026】 In one embodiment, the electromagnetic radiation of the laser device is configured to heat the inner workpiece and / or the outer workpiece and / or the central wire. For example, the optical unit of the laser device focuses the laser beam so as to heat a predetermined area of the inner workpiece and / or the outer workpiece, such as the interface between the inner workpiece and the outer workpiece, or to heat the central wire. By heating the inner workpiece and / or the outer workpiece, the respective workpiece materials absorb the electromagnetic radiation and directly melt and join together with the respective other workpiece under the contact pressure applied by the bearing element. After cooling, the inner workpiece and the outer workpiece are fused together. This method is also called fusion welding. Instead, the central wire absorbs the electromagnetic radiation and is thereby heated. Therefore, the central wire indirectly applies high temperature from the inside to the inner workpiece and the outer workpiece to fuse these two elements. 【0027】 The above problem is a method for joining, by laser welding in a welding area, an inner workpiece of a medical device, such as a catheter, to an outer workpiece, wherein the inner workpiece and the outer workpiece have a longitudinal axis, · a step of accommodating the inner workpiece and the outer workpiece in a bearing device provided with bearing elements; · a step of applying pressure to the outer workpiece through the bearing elements; · a step of emitting electromagnetic radiation for laser welding by a laser device and sending the emitted electromagnetic radiation through the bearing elements to the welding area, thereby laser welding the inner workpiece to the outer workpiece is further solved by a method having. 【0028】 As described above, the above method is a cost-effective method for permanently joining the inner workpiece and the outer workpiece of a medical device. In one embodiment, as described in more detail above, the inner workpiece is the inner tube or shaft of the catheter, or the outer tube or shaft, and the outer workpiece is the proximal balloon shaft or the distal balloon shaft. 【0029】 In one embodiment, the method further includes applying pressure to the outer workpiece via a bearing element and rotating the bearing element and / or the outer and inner workpieces about the longitudinal axis while emitting electromagnetic radiation. By this step, a circumferential or partially circumferential laser weld joint can be achieved between the inner and outer workpieces. 【0030】 In a further embodiment, the bearing device comprises at least one opposing bearing element, and the group of bearing elements and at least one opposing bearing element each comprises an element having a spherical, cylindrical, or at least partially spherical and / or cylindrical outer shape, and the method comprises clamping the outer workpiece by the bearing element and at least one opposing bearing element, the outer workpiece being pivotably clamped about the longitudinal axis by the bearing element and at least one opposing bearing element. Thus, since the workpiece is supported by at least one opposing bearing of the bearing device, a laser weld can be made between a less rigid outer workpiece and an inner workpiece. 【0031】 Also, in one embodiment of the above method, at least one of the bearing element and at least one opposing bearing element can further be moved along the radial direction of the inner and / or outer workpiece, for example, to facilitate accommodating the assembly formed by the inner and outer workpieces in the bearing device with higher accuracy, as described in more detail above. 【0032】 In one embodiment, the bearing element comprises a contour relief. By applying pressure to the outer workpiece by the bearing element, a contour structure can be imparted to the outer workpiece during and / or immediately after irradiation of the electromagnetic radiation by the laser device. At that time, the inner and / or outer workpiece is softened and / or melted. After cooling, the relief structure is fixed to each surface. The contour relief of the bearing element is a female mold of the contour structure of the outer workpiece. 【0033】 The steps of the following methods are also described in detail above. For example, in one embodiment, each of the bearing element and at least one opposing bearing element is rotated around an axis parallel to the longitudinal axis of the inner and / or outer workpiece. In another embodiment, the bearing element and at least one opposing bearing element are rotated around an axis perpendicular to the longitudinal axis of the inner and / or outer workpiece. Alternatively, or in addition to these, the laser device may be controlled to move the electromagnetic radiation beam along the bearing element that emits the electromagnetic radiation, for example, along an axis parallel to the longitudinal axis of the inner and / or outer workpiece. Furthermore, in one embodiment, a central wire is housed within the inner workpiece before laser welding. In another embodiment, the method further includes the step of directing an airflow to the welding area. 【0034】 After cooling, the assembly comprising the inner and outer workpieces is cooled and removed from the bearing device. Furthermore, the center wire is removed from the assembly. Prior to laser welding and housing within the bearing device, the assembly comprising the inner and outer workpieces may be pre-assembled, for example, by adhesive. 【0035】 The above problems are further solved by a catheter assembly having an inner workpiece and an outer workpiece that are directly attached to each other by laser welding, preferably by the method described above. In one embodiment of the catheter assembly, as described in more detail above, the inner workpiece is the inner or outer shaft of the catheter, and the outer workpiece is the proximal balloon shaft or the distal balloon shaft. In one embodiment, it has also been described that the shell surface of the inner workpiece and / or the shell surface of the outer workpiece are provided with relief structures, such as grooves extending in the longitudinal direction of the assembly, grooves extending in the circumferential direction, helical grooves, and / or tapered sections. 【0036】 The material of the inner and / or outer workpieces may include or be composed of thermoplastic materials, preferably from the group of materials including PA, PEBAX, PET, PC, POM, PEI, ABS, PEEK, PPS, PE, and PP. 【0037】 The various features and advantages of the present invention can be more readily understood by referring to the examples shown in the following detailed description and figures. In this specification, these figures illustrate the examples schematically and illustratively. [Brief explanation of the drawing] 【0038】 [Figure 1] These are top views of both a first embodiment of a laser welding apparatus and a catheter assembly of the first embodiment. [Figure 2] These are top views of both a second embodiment of a laser welding apparatus and a catheter assembly of the first embodiment. [Figure 3] The catheter assembly is also shown as a side view of the first embodiment, as well as a side view of the embodiment of the apparatus in Figure 1 and a side view of the embodiment of the apparatus in Figure 2. However, in the latter case, for clarity, only the bearing elements of the bearing device are shown, and the opposing bearing elements are omitted. [Figure 4] These are side views of both a third embodiment of a laser welding apparatus and a catheter assembly of a second embodiment. [Figure 5] This is a perspective side view of a third embodiment of a catheter assembly. [Figure 6] Figure 4 is a perspective view of the longitudinal cross-section of the embodiment. [Figure 7] This is a perspective side view of a fourth embodiment of a catheter assembly. [Figure 8] This is a perspective view of the longitudinal cross-section of the embodiment shown in Figure 6. [Figure 9] This is a perspective side view of a fifth embodiment of the catheter assembly. [Figure 10] This is shown in the longitudinal cross-sectional view of the embodiment in Figure 8. [Modes for carrying out the invention] 【0039】 The laser welding apparatus and corresponding methods of the present invention are described exemplified below with respect to catheter assemblies, particularly with respect to the joining of an inner shaft as an inner workpiece to a distal balloon shaft as an outer workpiece. The methods and apparatus of the present invention can also be used with respect to the fixation of an outer shaft to a proximal balloon shaft of a catheter, workpiece assemblies of other types of catheters or other medical devices such as endoscopes, or inlet and outlet elements or cable insulators of medical devices. 【0040】 Figures 1 and 3 show a first embodiment of a laser welding apparatus comprising a laser device 5 and a bearing device 10 for laser welding an inner shaft 21 to a distal balloon shaft 22 of a balloon catheter, where the inner shaft 21 is housed within the distal balloon shaft 22. The bearing device 10 comprises a sphere 11 that is transparent to electromagnetic radiation (i.e., a laser beam) supplied by the laser device 5. During laser welding, the first sphere 11 is housed in contact with the outer shell surface of the distal balloon shaft 22, thereby applying contact pressure to this surface. Furthermore, the catheter assembly is stabilized and rotated by a central wire 30 housed within the internal cavity of the inner shaft 21. The sphere 11 is rotatable about a longitudinal axis parallel to the longitudinal axis 25 of the inner shaft 21 and distal balloon shaft 22 shown in Figure 3. The sphere 11 is rotatably held by an airflow between two support / holding clamps 14, and the airflow is directed towards the sphere 11. 【0041】 The thermal energy required for welding is supplied by the laser device 5. The laser device comprises a laser beam generating unit 6, for example, a solid-state laser, and an optical unit 7 that forms a laser beam 8 generated by the laser beam generating unit 6 and focuses it on a predetermined area of ​​the catheter assembly or the central wire using the optical elements described above in a known manner. The solid-state laser supplies a laser beam 8 having a wavelength of, for example, 1.725 μm. As can be seen from Figures 1 and 3, the first sphere 11 contributes to the optical focusing of the laser beam 8 by diffraction at the surface of the sphere 11. In the illustrated first embodiment of the apparatus, the laser beam 8 is focused on the outer surface of the central wire 30, thereby heating the inner shaft 21 in contact with the outer surface of the central wire 30, and therefore also heating the distal balloon shaft 22. Thus, the distal balloon shaft 22 is welded to the inner shaft 21 in the region / welding region 100 in which the laser beam 8 delivers thermal energy to the central wire 30. Thermal energy for welding is supplied by a laser beam 8 along the entire circumference of the central wire 30, and by rotating the central wire 30, the spheres 11, 12 are rotated around an axis parallel to the longitudinal axis 25 of the catheter assembly, thereby making a welded connection along this region. The dimensions of the region / welding region 100 can vary, for example, depending on the material of the inner shaft 21 and / or distal balloon shaft 22, the deposition energy of the laser beam, and the pressure applied, from a very thin region extending only slightly within the inner shaft 21 and / or distal balloon shaft 22 to a very prominent region extending across the entire thickness of the inner shaft 21 and / or distal balloon shaft 22. In one embodiment, the catheter assembly and / or device can be moved longitudinally (i.e., along the axis 25) to provide a longitudinally extending welded connection between the inner shaft 21 and the distal balloon shaft 22. 【0042】 The catheter balloon further comprises a distal cone 23, an action portion 24 (see Figure 3), and a proximal cone and proximal shaft (not shown in Figures 1 and 3). The proximal shaft can be laser-welded to the proximal shaft of the catheter (not shown) in a similar manner. For example, the inner shaft 21 may have an inner diameter of 0.40 mm and an outer diameter of 0.55 mm, and the distal balloon shaft 22 may have an inner diameter of 0.60 mm and an outer diameter of 0.90 mm. The distal balloon shaft 22 and the proximal balloon shaft may have a length of 1.5 mm (in the longitudinal direction), the distal and proximal cones may have a length of 5 mm (in the longitudinal direction), and the action portion 24 may have a length of 20 mm (in the longitudinal direction). 【0043】 In laser welding, the central wire is first slid into the internal cavity of the inner shaft. Before or after this, the balloon is positioned such that the distal balloon shaft is within a predetermined distance from the distal end of the inner shaft, and is pre-assembled in this position, for example, by adhesive. The assembly with the central wire is then housed in the bearing device 10. This can be easily done, for example, by opening the bearing by moving the first sphere 11 perpendicular to the longitudinal axis 25 (opposite direction to arrow 15), housing the assembly in the bearing, and returning the first sphere 11 so that predetermined contact pressure is applied to the outer shell surface of the distal balloon shaft 22 by each of the spheres 11 and 12. Laser welding is then performed by the laser device 5, in which case the laser beam is directed through the first sphere 11 to the central wire 30. The welding is performed under rotational motion of the central wire 30, and therefore rotational motion of the catheter assembly, and, if applicable, longitudinal movement of the central wire 30, to achieve a welded joint within a predetermined welding area. 【0044】 Figure 2 shows a second embodiment of the apparatus for laser welding. The bearing device 110 comprises three spheres 11, 12 with an angular spacing of 120°, in which case the first sphere 11 is transparent to the electromagnetic radiation (i.e., laser beam) supplied by the laser device 5. In laser welding, the first sphere 11 and the two second spheres 12 are housed in contact with the outer shell surface of the distal balloon shaft 22, thereby applying contact pressure to this surface. Furthermore, the catheter assembly is stabilized and rotated by a central wire 30 housed within the internal cavity of the inner shaft 21. Each of the spheres 11, 12 is rotatable about a longitudinal axis parallel to the longitudinal axis 25 of the inner shaft 21 and the distal balloon shaft 22 shown in Figure 3. Each of the spheres 11 and 12 is rotatably held by the airflow between the two support / holding clamps for each sphere 11 and 12, with the airflow directed towards the corresponding spheres 11 and 12. For clarity, Figure 2 shows only the support / holding clamp 14 for sphere 11. 【0045】 Figures 4 to 10 show further embodiments of the laser welding apparatus and catheter assembly. Components of the apparatus or catheter assembly similar to those in each of the first embodiments described above are denoted by the same reference numerals plus a multiple of 100. Therefore, please refer to the above description relating to the first embodiment for these components. 【0046】 Figure 4 shows a third embodiment of the apparatus for laser welding. Compared to the first and second embodiments, the third embodiment includes a cylindrical body 111 as a rotatable element, which transmits electromagnetic radiation emitted from the laser. The cylindrical body 111 is basically cylindrical / conical. The cylindrical body 111 can be combined with the sphere 12 of the second embodiment shown in Figure 2, or it can be combined with two further cylindrical bodies equivalent to or identical to the cylindrical body 111 instead of the sphere 12. In this case, the two further cylindrical bodies or spheres 12 are arranged similarly to the two second spheres 12 of the second embodiment. Furthermore, the cylindrical body 111 has specific surface reliefs to form the shell surfaces of the inner shaft 121 and the outer shaft 122, as predetermined during welding and as described above. In this embodiment, the proximal portion 111a and distal portion 111b of the cylindrical body 111 are conical. Furthermore, a cylindrical central portion 111c is provided. As a result, the distal end 122a of the distal balloon shaft 122 is formed in a conical shape, thereby providing a transition from the inner shaft 121 to the balloon. The distal portion 111b of the first cylindrical body forms its conical tip at the distal end of the inner shaft 121. The cylindrical rotatable element 111 does not move in the longitudinal direction. 【0047】 As can be seen from Figure 4, the laser beam 108 is not focused as a point, but as a line, and is focused at the interface between the inner shaft 121 and the distal balloon shaft 122 (the laser beam 108 travels along direction 115). For clarity in the figure, the rectangular area representing the laser beam 108 does not depict the entire path to this interface. The linear shape of the laser beam 108 has the advantage that welding and forming of the shell surface of the distal balloon shaft 122 and the distal end of the inner shaft 121 can be performed simultaneously along a predetermined length (e.g., 2 mm) along the longitudinal direction without moving the central wire 130 or the laser device in the longitudinal direction. This allows for a more accurate laser welded connection in less time. The shell surface can be formed even more precisely. 【0048】 Figures 5 to 10 show further examples of laser-connected catheter assemblies having various profiles or contour structures on the shell surfaces (of the distal ends of the inner shafts 221, 321, and 421, and the distal balloon shafts 222, 322, and 422), all of which are generated by bearing elements (e.g., first spheres or cylinders) or their respective protrusions used during welding. 【0049】 The embodiment shown in Figures 5 and 6 features four grooves 221a and 222a extending longitudinally on the outer shell surface of the inner shaft 221 and distal balloon shaft 222. The grooves 221a and 222a reduce the cross-sectional area of ​​the inner shaft and distal balloon shaft, thereby facilitating introduction into the lesion. 【0050】 The spiral grooves 321a and 322a are formed on the outer shell surface of the inner shaft 321 and distal balloon shaft 322 in the embodiments shown in Figures 7 and 8, thereby improving the bending flexibility of each region. 【0051】 Referring to Figures 9 and 10, a circular groove 421a extending along the entire circumference of the inner shaft 421 is provided on the outer shell surface of the inner shaft 421 at a position immediately distal to the most distal end of the distal balloon shaft 422, which has a tapered portion 421b. This particular configuration improves the bending flexibility of the corresponding portion of the inner shaft (e.g., the portion forming the catheter tip) while maintaining good indentation in this portion (including the transition portion to the balloon). 【0052】 The embodiments shown in Figures 5 to 8 have tapered sections 221b and 321b on the inner shafts 221 and 321, which also provide a transition section to the balloon. In these sections 221b, 321b and 421b, the wall thickness of the inner shaft increases in the proximal direction. 【0053】 All of the above embodiments can be manufactured using the method described with respect to the first embodiment. Each manufacturing method is adapted only with respect to the form / output of the laser beam, or the movement of the device relative to the catheter assembly / central wire, and the form of at least two (e.g., three) rotatable elements of the bearing device to achieve specific characteristics of the laser-welded connection between the inner shaft and the distal balloon shaft, and specific characteristics of the shell surface profile. 【0054】 The method described above has the advantages of being less complex and cost-effective. It is fully automatable. Furthermore, it has been shown to be more accurate with respect to welded connections and to provide a clear transition from the welded area to the non-welded area.

Claims

[Claim 1] An apparatus for laser welding an internal workpiece (21, 121, 221, 321, 421) of a medical device, such as a catheter, to an external workpiece (22, 122, 222, 322, 422) in a welding area, wherein the internal workpiece (21, 121, 221, 321, 421) and the external workpiece (22, 122, 222, 322, 422) have a longitudinal axis (25), A bearing device (10) comprising bearing elements (11, 111), wherein the bearing elements (11, 111) are configured to apply pressure to the external workpiece (22, 122, 222, 322, 422), and A laser device (5) that emits electromagnetic radiation for welding, wherein the emitted electromagnetic radiation is sent to the welding area through the bearing elements (11, 111) and A device equipped with the following features. [Claim 2] The apparatus according to claim 1, wherein the bearing device (10) comprises at least one opposing bearing element (12), each of the group of bearing elements (11, 111) and the at least one opposing bearing element (12) comprises an element having a spherical, cylindrical, or at least partially spherical and / or cylindrical outer shape, and the bearing elements (11, 111) and the at least one opposing bearing element (12) house the outer workpiece (22, 122, 222, 322, 422) so as to be clamped by the bearing elements (11, 111) and the at least one opposing bearing element (12) so as to be pivotable around the longitudinal axis (25). [Claim 3] The apparatus according to claim 1 or 2, wherein the bearing device (10) and the laser device (5) are configured to be rotatable about the longitudinal axis (25). [Claim 4] The apparatus according to any one of claims 1 to 3, wherein each of the bearing elements (11, 111) and, when dependent on claim 2, the at least one opposing bearing element (12) is rotatable about an axis parallel to the longitudinal axis (25). [Claim 5] The apparatus according to any one of claims 1 to 4, wherein the bearing elements (11, 111) and, when dependent on claim 2, at least one of the at least one opposing bearing elements (12) are configured to direct the airflow toward the welding area. [Claim 6] The apparatus according to any one of claims 1 to 5, wherein the bearing elements (11, 111) and, when dependent on claim 2, at least one of the at least one opposing bearing elements (12) are provided with contour reliefs (111a, 111b, 111c) for forming contours on the contours of the outer workpiece shell surface and / or the inner workpiece shell surface. [Claim 7] The apparatus according to any one of claims 1 to 6, further comprising a central wire (30) configured to be housed within the internal workpieces (21, 121, 221, 321, 421). [Claim 8] A method for joining an internal workpiece (21, 121, 221, 321, 421) of a medical device, such as a catheter, to an external workpiece (22, 122, 222, 322, 422) by laser welding in a welding area, wherein the internal workpiece (21, 121, 221, 321, 421) and the external workpiece (22, 122, 222, 322, 422) have a longitudinal axis (25), The steps include housing the internal workpieces (21, 121, 221, 321, 421) and the external workpieces (22, 122, 222, 322, 422) in a bearing device (10) equipped with bearing elements (11, 111), The steps include applying pressure to the outer workpiece (22, 122, 222, 322, 422) via the bearing elements (11, 111), The steps include: emitting electromagnetic radiation for laser welding using a laser device, sending the emitted electromagnetic radiation through the bearing elements (11, 111) to the welding area, thereby laser welding the inner workpiece (21, 121, 221, 321, 421) to the outer workpiece (22, 122, 222, 322, 422); A method of having. [Claim 9] The method of claim 8, further comprising the step of applying pressure to the outer workpiece (22, 122, 222, 322, 422) via the bearing elements (11, 111) and / or rotating the bearing elements (11, 111) and / or the outer workpiece (22, 122, 222, 322, 422) and the inner workpiece (21, 121, 221, 321, 421) around the longitudinal axis (25). [Claim 10] The bearing device (10) comprises at least one opposing bearing element (12), and each of the group of bearing elements (11, 111) and the at least one opposing bearing element (12) comprises an element having a spherical, cylindrical, or at least partially spherical and / or cylindrical outer shape. The method according to claim 8 or 9, comprising the step of clamping the outer workpiece (22, 122, 222, 322, 422) with the bearing elements (11, 111) and the at least one opposing bearing element (12), wherein the outer workpiece (22, 122, 222, 322, 422) is clamped by the bearing elements (11, 111) and the at least one opposing bearing element (12) so as to be pivotable around the longitudinal axis (25). [Claim 11] The method according to any one of claims 8 to 10, wherein the bearing element (111) comprises contour reliefs (111a, 111b, 111c). [Claim 12] The method according to any one of claims 8 to 11, wherein each of the bearing elements (11, 111) and, when dependent on claim 11, the at least one opposing bearing element (11, 12, 111) is rotated about an axis parallel to the longitudinal axis (25). [Claim 13] The method according to any one of claims 8 to 12, comprising the step of directing an airflow to the welding area. [Claim 14] The method according to any one of claims 8 to 13, wherein the central wire (30) is housed within the internal workpiece (21, 121, 221, 321, 421) before laser welding. [Claim 15] A catheter assembly having internal workpieces (21, 121, 221, 321, 421) and external workpieces (22, 122, 222, 322, 422) directly joined to each other by laser welding according to any one of claims 8 to 14. [Claim 16] The catheter assembly according to claim 15, wherein the shell surface of the inner workpiece (121, 221, 321, 421) and / or the shell surface of the outer workpiece (22, 122, 222, 322, 422) is provided with a contour structure, for example, longitudinally extending grooves (221a, 222a), circumferentially extending grooves (421a), helical grooves (321a, 322a), and / or tapered portions (221b, 321b, 421b).

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