Vacuum mixer
Vacuum mixers represent a special design of mostly heated mixers , which are characterized by a vacuum- resistant vessel. In this way, parallel to the actual mixing of solid or liquid mixtures, further basic procedural operations can be carried out in negative pressure, such as for example
- Venting, degassing, for example, of ( ultra-high-strength ) concrete or cast resin
- dry
- Vacuum contact drying ,
- Vacuum convection drying or
- Vacuum hot steam drying
- Evaporative cooling
be performed.
Types
A distinction can be made between two types of vacuum mixers:
1. Mixer with a fixed mixing container, such as a pipe mixer . With these mixer types, the wall thickness of the mixing container is increased to the required level of vacuum resistance and the shaft feedthroughs for the mixing tools as well as the feed and discharge openings are made vacuum-tight. Since with these types of construction the product usually comes into direct contact with the shaft feedthroughs of the mixing tools or the emptying opening, the wear and tear requires complex seals.
2. Mixers with rotating mixing containers, such as pan mixers . With these mixer types, the rotating mixing container is installed in a vacuum-tight housing that tightly encloses the mixing container. The shaft feed-through and the feed and discharge openings are vacuum-tight. Since in this design neither the shaft feed-through for the overhung mixer tool nor the sealing of the emptying opening in the vacuum-proof housing comes into contact with the product, the seals can be made relatively simple.
If degassing is to take place in the mixer, it often also has cone-like built -in components through which the material to be mixed is conveyed in order to enable the largest possible surface and thus effective degassing (so-called thin-film degassing).
Individual evidence
- ↑ Gottfried W. Ehrenstein: Fiber composite plastics. Materials - processing - properties . 2nd, completely revised edition. Hanser, Munich et al. 2006, ISBN 3-446-22716-4 , p. 189: Chapter 5: Processing ( limited preview in Google Book Search).