Negative pressure vacuum equipment: 60° and 90° cones, which one has a stronger resistance to negative pressure?

In negative pressure vacuum devices, a 90° cone has greater resistance to negative pressure. When a negative pressure is created in the vacuum device, the air inside the cone is drawn out, creating a vacuum. The strength ξ of a material can also be defined as \"the ability of a substance to remain intact and maintain its functionality under specific forces in a given environment.\" Therefore, the resistance to negative pressure is actually related to the strength of the material. Compared to a 60° cone, a 90° cone has a larger surface area for the same length of its cone surface, allowing it to hold more air inside. In this way, when a negative pressure is created, more air inside the 90° conical object is drawn out, resulting in a stronger vacuum effect. Therefore, a 90° cone has relatively strong resistance to negative pressure. Furthermore, the shape also has a significant impact. For example, a 90-degree cone has a more secure connection between its side walls and base wall, offering better structural stability and the ability to better withstand the effects of negative pressure. Therefore, from a theoretical analysis perspective, the negative pressure resistance of a 90° cone will be greater than that of a 60° cone. However, in practical engineering applications, it is influenced by various factors such as the material of the cone, its size, the manufacturing process, and the operating environment; therefore, the specific negative pressure resistance must be determined based on the actual conditions. .

Thank you for your guidance; I still have some questions and would like to ask you again: (1) You mentioned that a 90° conical surface has a larger area for the same length. Pressure = pressure intensity * area; since the pressure intensity is -0.1 MPa, a larger area means that the pressure exerted is not greater? At the same vacuum level, a 90° cone withstands greater pressure and has weaker resistance to negative pressure. (2) 90° cone, whose side wall and base wall are more firmly connected, offering better structural stability. Which edges do you mean by the side walls and bottom wall? Also, I couldn’t understand this sentence; could you please explain it further? Thank you again for your help, sir.

90 degrees, because a 90-degree cone can essentially be treated as a flat lid, and flat lids do not have stability issues; therefore, they have a greater resistance to negative pressure.

This post was last edited by FORREST_GUMP on 2023-10-30 at 10:31. Long time no see, Sister GN. I used SW6 for the calculations, and the results showed that cones with a 90° angle have greater resistance to negative pressure. But I’ve always had a question: I once built a small vacuum tank with dimensions of Φ600x1000 and a thickness of 4, using flat lids at both ends (created by cutting 4mm thick sheets into circular shapes). During use, both flat lids sank inwards – they were drawn into the tank. It was remade later, with the end plates made into cones of about 150°, and the cones did not collapse inward. Both the flat cover and the cone have a thickness of 4. Can this fact be used to conclude that the flat cover has a weaker resistance to negative pressure than the cone?

The 2nd floor seems to be AI. 150.3 states that for those with a half-apex angle ≤ 60°, calculation shall be done using an equivalent cylinder. Therefore, the 90° cone in the diagram has strong load-bearing capacity

Oh, it’s the book on engineer training tutorials

The topics and replies posted by Haiyou on the 2nd floor also seem like they were generated by AI to me. But his reply was quite targeted; he hit the right point – technology is indeed amazing. Sir, let me get more specific: cones with different angles – 60°, 90°, 120°, 150°, 180° (which becomes a flat surface). Only the angle varies; all other parameters remain the same. What is their resistance to negative pressure in order?

If a flat cover is used, the calculation model changes, so it’s not possible to make a direct judgment; calculations are necessary. The compressive resistance (not just negative pressure) is much weaker, and the calculation methods for internal and external pressures on flat covers are the same

Similarly, by calculating the equivalent cylinder length, we can determine it; thus, an angle of 120 degrees is the strongest among angles up to 120 degrees, while for larger angles, it’s impossible to know (this is according to the standard method; in practice, within the range of 120–180 degrees, perhaps an angle of 133 degrees or some other higher value could be the strongest), and calculations are needed to determine this. It seems the tablet’s performance isn’t good enough

Am I understanding this correctly: within the range of 0~120° (with the half-apex angle ranging from 0~60°), as the angle α increases, the average radius of curvature R increases, the critical pressure of the shell decreases, and thus its resistance to negative pressure improves.