High-Pressure Synthesis of industrial diamonds / CBN products are manufactured under extreme conditions: 1400-1500°C and 55-80 kbar pressure in the capsule. These extreme conditions put high demands on the press system including the high-pressure tooling, the HPS capsule itself, process controls, handling system, etc.
In addition to the high-strength prestressing tool system based on the stripwinding technology, STRECON has developed a hydraulic equipment solution for horizontal alignment of the die container (belt). The main purpose is to prevent the die container from tilting, and through that achieve improved process stability, avoidance of blowouts and tool failures, increased yield of high-quality diamonds, and improved press uptime (OEE). The equipment has been named ALS, which is an acronym for Alignment System.
The concept of hydromechanical parallelism is widely used in the industry and for many different industrial applications. The main idea is to ensure perfect parallelism of for example an upper and lower part of tooling and/or machine system in manufacturing processes with high demands for precision and/or process stability.
STRECON has developed a mechanical system for high precision parallelism, which is based on the hydraulic principle of equal displacement of fluid. This means that the hydraulics by itself ensures that the fluid is equally displaced between the cylinders that are built into the overall mechanical system, and consequently it offers a mechanical system in “perfect” alignment defined by a certain system capability.
The ALS technology offers a torque capability up to 1,6 mil. Nm and a very limited misalignment in the mechanical system. The exact misalignment depends on the nature, materials, and physical sizing of the specific mechanical system but practically speaking, the misalignment (or lack of perfect parallelism) can be expected to be very small.
STRECON’s technology does also consist of a sub-hydraulic system that is designed to ensure a precise height positioning of the upper and lower tools or machine parts. The hydraulic force is up to 500T, which is valued to be sufficient for handling possible mechanical inconsistencies or unintended friction issues in the process of aligning the two said elements.
The overall hydromechanical parallel system is set, operated, and monitored with its own controls system.
Manufacturing of industrial diamonds / CBN products is a maturing industry with a key focus on high yield of quality products as well as low costs per carat. Industry has taken different manufacturing systems in use including the belt type system, the multi-anvils system, and the Toroidal 2-anvils system. The belt type system allows in general for larger capsules than the other two HPS press systems and suggests to being a more cost-effective manufacturing system. However, traditional press-tool designs do not effectively support the large die container from tilting as it practically speaking is resting on the nose of the lower carbide anvil. The assembly and insertion of the capsule as well as the mechanical alignment of the die container is crucial when starting up the press cycle, and even a small misalignment of the tool set θ can result in critical tilting of the die container. This mechanical challenge does only become greater with larger HPS capsules and corresponding tool systems as well as with higher process pressure.
STRECON has developed a hydromechanical tool alignment system for the belt type press system. The system technology, called ALS, is based on a 2-string hydraulic system that has been integrated with each anvil tooling. One string focuses on the horizontal alignment of the die container while the second string is designed for controlled vertical movement of the two anvil assemblies into the die container.
The ALS system can deliver a torque up to 1,6 mil. Nm, which would correspond to a maximum tilt of the die container of θ ≤ 0,5°. However, in actual applications the horizontal alignment (read anti-tilt) can be achieved to be less than θ ≤ 0,2°.
The accuracy of the vertical positioning of the anvil assemblies (x-y) can be achieved to max. 1 mm, and the position is supported by a hydraulic force up to 500T.
In addition to the height positioning, the ALS system does also ensure a horizontal tool centering of the anvils to the carbide die with an accuracy of max 0,5 mm after assembly of the tool set, and during the very early stage of system loading.
The ALS system consists of up to eight (8) hydraulic cylinders on each anvil assembly, which are operated and controlled by a separate controls system, which again is I/O controlled by the overall press controls system.
The alignment system technology (ALS) has been developed for the belt type press system but can also be adapted for the Toroidal 2-anvils press system. The value of ALS seems to correspond well to medium to large system sizes and/or extreme pressure levels, for example, hydraulic presses larger than 500T press force, and HPS systems running at pressure levels higher than 60 kbar.
Due to the complexity and different customer needs, the ALS system would be subject to customization in each customer project.