Tool for ultrasonic welding device

Abstract

Tool for ultrasonic welding device, comprising a carrier body (1) made of metal with a contact surface facing a component to be welded, which is provided with a diamond layer (3), wherein the diamond layer (3) is produced by CVD process and has a thickness (D2) in the range of 0.5 to 20 µm, characterized by the fact that - the support body (1) is made of titanium or a titanium alloy and a TiC layer (2) with a further thickness (D1) in the range of 10 nm to 2.0 µm, preferably 0.5 to 2.0 µm, is inserted between the support body (1) and the diamond layer (3). or - the carrier body (1) is made of steel and an intermediate layer (2) of chromium carbide or TiN is inserted between the carrier body (1) and the diamond layer (3), which has a further thickness (D2) in the range of 1 to 50 µm, preferably 1 to 5 µm, wherein the diamond layer (3) exhibits a first peak in the range of 1335 to 1345 1 / cm and a second peak in the range of 1345 to 1355 1 / cm in the Raman spectrum.

Description

[0001] The invention relates to a tool for an ultrasonic welding device according to the preamble of claim 1.

[0002] A generic tool for an ultrasonic welding device is known from EP 0 477 585 A2. A contact surface facing a component to be welded is provided with a diamond layer produced by a CVD process. The diamond layer can have a thickness of 1 to 200 µm.

[0003] Document US 2008 / 0 070 049 A1 describes the deposition of a boron-doped diamond layer on a titanium substrate.

[0004] From DE 10 2009 044 876 A1, the use of a titanium-containing carrier body with a diamond coating as a tool for an ultrasonic welding device is known.

[0005] German patent DE 101 27 824 A1 describes a sonotrode with a diamond coating. An intermediate layer, for example of chromium carbide, is first deposited onto a substrate, for example made of steel, before the diamond layer is applied using CVD.

[0006] A tool for an ultrasonic welding device is also known, for example, from WO 2009 / 060 080 A2. In the known tool, the diamond layer is made of polycrystalline diamond (PCD). In PCD, diamond crystals are randomly oriented within a metal matrix. PCD is produced by sintering at high pressure and high temperatures. To produce the known tool, a carrier holding the PCD must be joined to the relevant tool part, for example, by soldering. The production of the known tool is complex and expensive. Moreover, it cannot always reliably prevent unwanted adhesion of a component to be welded to the tool.

[0007] The object of the invention is to eliminate the disadvantages of the prior art. In particular, it aims to provide a tool for an ultrasonic welding device that is as simple and cost-effective to manufacture as possible and that reliably prevents the component being welded from sticking. A further objective of the invention is that the tool should exhibit improved durability, especially under continuous use.

[0008] This problem is solved by the features of claim 1. Advantageous embodiments of the invention result from the features of claims 2 to 9.

[0009] According to the invention, it is proposed that the diamond layer be produced by CVD and have a thickness in the range of 0.5 to 20 µm. A diamond layer produced by CVD is characterized by the fact that, unlike a PCD layer, it does not contain a metallic binder phase. Such a diamond layer is essentially single-phase. Surprisingly, it has been found that this diamond layer withstands the thermal and mechanical stresses of ultrasonic welding exceptionally well. Moreover, the diamond layer produced by the CVD process is characterized by a particularly low tendency to bond to the components to be welded.

[0010] The proposed diamond layer has a thickness in the range of 0.5 to 20 µm, preferably less than 20 µm. A tool coated with a diamond layer according to the invention with a thickness in the range of 0.5 to 20 µm is characterized by a particularly long service life despite the extreme stresses during ultrasonic welding.

[0011] In an advantageous embodiment, the diamond layer has a thickness in the range of 1 to 15 µm, preferably 1.5 to 5.0 µm. Diamond layers with a thickness in the range of 2 to 12 µm are characterized by excellent durability. Such diamond layers can be produced relatively easily and cost-effectively using the CVD process.

[0012] The diamond layer exhibits a first peak in the range of 1335 to 1345 1 / cm and a second peak in the range of 1345 to 1355 1 / cm in the Raman spectrum, particularly at a wavelength of 514.5 mm (green laser light). The two observed peaks are the result of stress-induced peak shifting and peak splitting of a peak characteristic of a relaxed diamond lattice, located at 1332.5 1 / cm. This means that the diamond layer produced by the CVD process advantageously exhibits residual stresses. It is assumed that these residual stresses contribute to the improved durability of the diamond layer. The residual stresses σ are expediently 1 to 6 GPa, preferably 1 to 5 GPa, and particularly preferably 1 to 4 GPa.

[0013] According to a further embodiment of the invention, the thickness of the diamond layer deviates from an average diamond layer thickness by a maximum of 10%. It has been shown that the proposed uniform thickness of the diamond layer, in turn, contributes to improved durability when using the proposed tool for ultrasonic welding devices.

[0014] Advantageously, the mean diameter of the diamond crystals forming the diamond layer at a surface of the diamond layer is 0.05 to 20 µm, preferably 0.5 to 3.0 µm. That is, the proposed diamond layer is characterized by diamond crystals with a relatively small mean diameter at the surface.

[0015] According to a further embodiment of the invention, the thermal conductivity of the diamond layer is 2 to 2000 W / mK. The use of a diamond layer with a thermal conductivity in the range of 500 to 1500 W / mK is preferred. High thermal conductivity helps to dissipate the heat transferred from the component to the diamond layer to the substrate as quickly as possible. This further helps to prevent the components to be welded from sticking to the tool.

[0016] According to a further embodiment of the invention, the diamond crystals contain 50 to 100,000 ppm of boron. Surprisingly, a boron-impregnated diamond layer exhibits a particularly long service life. According to a further advantageous embodiment, a diamond layer with electrical conductivity is used. The specific resistance of the diamond layer is expediently 10 Ω. -3 up to 10 4S / m. The use of an electrically conductive diamond layer makes it possible to detect damage to the diamond layer by continuously measuring its specific resistance and, in particular, to switch off automatically operating ultrasonic welding devices in time to prevent further damage.

[0017] The support body is made of titanium, a titanium alloy, or steel.

[0018] In a substrate made of titanium or a titanium alloy, a TiC layer with a thickness in the range of 10 nm to 2.0 µm, preferably 0.5 to 2.0 µm, is interposed between the substrate and the diamond layer. The proposed TiC layer, in turn, contributes to improved durability of the diamond layer. By providing a suitable TiC layer, the resistance of the diamond layer to chipping from the substrate can be significantly improved.

[0019] In a steel substrate, an intermediate layer of chromium carbide or TiN is inserted between the substrate and the diamond layer. This layer has a thickness in the range of 1 to 50 µm, preferably 1 to 5 µm. This intermediate layer also contributes to improved adhesion of the diamond layer to the substrate.

[0020] The tool according to the invention can comprise at least one of the following elements: sonotrode, anvil, side slide. In particular, static elements, such as the anvil or side slide, are preferably provided with the diamond layer according to the invention.

[0021] The support body can also be advantageously designed as an insert for placement in a corresponding recess on the anvil. In this case, the support body is designed, for example, as a flat metal plate.

[0022] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. The drawings show: Fig. 1 a schematic layer view created by a tool and Fig. 2 Raman spectra of different CVD diamond layers.

[0023] Fig. Figure 1 shows a schematic partial cross-sectional view through a tool according to the invention, for example, an anvil or a side slide of an ultrasonic welding device. The tool has a carrier body 1 made of metal. The metal is, for example, Ti-6Al-4V. Reference numeral 2 denotes an intermediate layer, which here is formed of TiC. The intermediate layer 2 has a first thickness D1 of about 0.5 to 1.5 µm. The intermediate layer 2 is superimposed by a diamond layer 3. The diamond layer 3 has a second thickness D2 of preferably 2 to 12 µm. It is formed from diamond crystals 4, which extend substantially perpendicularly from the interface to the intermediate layer 2. The diamond crystals 4 have a diameter d of 0.05 to 5.0 µm at a surface O. An average diameter (not shown here) is expediently 0.5 to 3.0 µm.The diameter d of the diamond crystals 4 is advantageously smaller than the second thickness D2. The mean diameter is expediently 0.1 to 0.8 times the second thickness D2.

[0024] To manufacture the tool, the surface of the carrier body to be coated is first ground, using a grit size in the range of 2000 to 5000, preferably 3000 to 4500. The surface can also be electrochemically eroded. Subsequently, the surface can be blasted with an abrasive at 2 to 4 bar. The abrasive can be, for example, SiC with a mean grain size in the range of 20 to 50 µm. Furthermore, the surface thus prepared can be etched. Finally, diamond nuclei are advantageously applied to the surface.

[0025] The production of the in Fig. The CVD diamond layer 3 shown in Figure 1 is applied, for example, by means of hot-filament chemical vapor deposition (HF-CVD). The gas phase used can contain 0.5 to 4.0 vol%, preferably 1.0 to 1.5 vol%, methane. Furthermore, 96.0 to 99.5 vol% hydrogen and optionally 1.5 to 3.5 vol% oxygen and / or boron can be added to the gas phase. The gas pressure during the coating process is 8 to 12 mbar, preferably 10 mbar.

[0026] Fig. Figure 2 shows Raman spectra of various diamond layers deposited onto a Ti-6Al-4V substrate using HF-CVD technology. The deposition pressure was 10 mbar in each case. The hydrogen flow rate was 1000 ml / min and the methane flow rate was 10 ml / min. The in Fig. The two Raman spectra shown were each recorded for diamond layers produced with increasing heating wire power and substrate temperature.

[0027] As from Fig.As can be seen in Figure 2, the produced diamond layers do not show a peak at 1332.5 1 / cm, which would indicate an unstrained diamond lattice. In contrast, all CVD diamond layers show a first peak in the range of 1335 to 1345 1 / cm and a second peak in the range of 1345 to 1355 1 / cm. The first peak corresponds to the singlet phonon vibration, and the second peak to the doublet phonon vibration. The first and second peaks arise from a peak splitting of the peak at 1332.5 1 / cm, which indicates an unstrained diamond lattice. This peak splitting is caused by residual stresses in the diamond layer. From the position of the first and second peaks, it can be concluded that the produced CVD diamond layers exhibit residual stresses σ in the range of 1 to 6 GPa. It has proven advantageous to use CVD diamond coatings for tools for ultrasonic welding devices, which have residual stresses in the range of 1 to 4 GPa.

[0028] With regard to the coating of a tool for ultrasonic welding devices, it has proven particularly advantageous if a quotient of the second thickness D2 and the residual stress σ has a value K in the range of 0.2 to 15 µm / GPa, preferably 0.8 to 10 µm / GPa, particularly preferably 1 to 4 µm / GPa: K=D2 / σ=0.2…15 μm / GPa

[0029] Diamond coatings with the aforementioned value K are characterized by particularly high durability when used in conjunction with tools for ultrasonic welding devices. Reference symbol list 1 Carrier body 2 Intermediate layer 3 diamond layers 4 diamond crystals d diameter D1 first thickness D2 second thickness Surface

Claims

[1] Tool for ultrasonic welding device, comprising a carrier body (1) made of metal with a contact surface facing a component to be welded, which is provided with a diamond layer (3), wherein the diamond layer (3) is produced by CVD process and has a thickness (D2) in the range of 0.5 to 20 µm, characterized by , that - the support body (1) is made of titanium or a titanium alloy and a TiC layer (2) with a further thickness (D1) in the range of 10 nm to 2.0 µm, preferably 0.5 to 2.0 µm, is inserted between the support body (1) and the diamond layer (3). or - the carrier body (1) is made of steel and an intermediate layer (2) of chromium carbide or TiN is inserted between the carrier body (1) and the diamond layer (3), which has a further thickness (D2) in the range of 1 to 50 µm, preferably 1 to 5 µm, wherein the diamond layer (3) exhibits a first peak in the range of 1335 to 1345 1 / cm and a second peak in the range of 1345 to 1355 1 / cm in the Raman spectrum. [2] Tool according to claim 1, wherein the diamond layer (3) has a thickness (D2) in the range of 1 to 15 µm, preferably 1.5 to 5.0 µm. [3] Tool according to one of the preceding claims, wherein the thickness (D2) of the diamond layer (3) deviates from an average thickness of the diamond layer (D3) by a maximum of 10%. [4] Tool according to one of the preceding claims, wherein the mean diameter of the diamond crystals (4) forming the diamond layer (3) at a surface (O) of the diamond layer (3) is 0.05 to 20 µm, preferably 0.5 to 3.0 µm. [5] Tool according to one of the preceding claims, wherein the thermal conductivity of the diamond layer (3) is 2 to 2000 W / mK. [6] Tool according to any of the preceding claims, wherein the diamond crystals (4) contain 50 to 100000 ppm of boron. [7] Tool according to one of the preceding claims, wherein a specific resistance of the diamond layer (3) 10 -3 up to 10 4 S / m is. [8] Tool according to any of the preceding claims, comprising at least one of the following elements: sonotrode, anvil, side slider. [9] Tool according to one of the preceding claims, wherein the carrier body (1) is designed as an insert for insertion into a corresponding recess on the anvil.

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