Wood screws, one of which is a polished rod, the angle and pitch of the teeth of the wood screws and self-tapping are different. Self-tapping screws have high hardness, wide thread spacing, deep threads, and uneven surface, while wood screws are the opposite. Another difference is more obvious. Wood screws have no threads at the rear. Self-tapping screws are generally subject to heat treatment, and wood screws are not required. The concept of self-tapping screws is actually very general, because there are many kinds of them according to different head types. Use of wood screws: Similar to machine screws, but the thread on the screw is a special rib for wood screws, which can be directly screwed into wooden components (or parts).
In the prior art, the beams used for installing the curtain wall are mainly divided into two types: closed-cavity structure and open structure, and angle aluminum connection is mainly used for the connection between the beam and the column. As far as the beam of the closed-cavity structure is concerned, after the angle aluminum is used to connect, there are open bolts on both ends of the upper surface of the beam, and the aesthetic performance is extremely poor. As far as the beam of the open structure is concerned, in the actual connection, first fix one corner of the angle aluminum to the beam, and then connect the other corner of the angle aluminum to the column; due to the limited operating space in the beam of the open structure, the angle aluminum is not It is easy and accurate to install, and it takes a lot of time to install; and when the curtain wall panel is heavy, the beam will be twisted, causing the gusset of the opening part of the beam to fall. In addition, due to the limitation of the opening structure itself (an additional gusset or clasp), the aluminum content of the beam is relatively heavy, and the manufacturing cost is high.
With the development of the economy, automobiles have become an indispensable means of transportation in people's lives, and the production, sales and after-sales services of automobiles have also developed rapidly. Automobile wheels and steel rings are an important part of auto parts and are also related to The use of the car is safe. The connection between the car wheel and the steel ring is realized by bolts, so the bolts and nuts need to have good fixation.
This clearance determines how much the bone fragment fixed by means of the locking screw in the corresponding locking hole can move relative to the nail and thus also relative to other bone fragments fixed by the same nail due to the rigidity of the nail. Together with the flexibility of the material and the overall device this can build up to a size that prevents or decisively delays effective healing. In order to ensure the applicability of the locking device to the surgeon, this gap, although unavoidable, is clinically undesirable in some indications (eg in the case of metaphyseal fragments). Even a screw with a full cross-section, which can have an internal thread in the locking hole, is not gapless. This internal thread only prevents possible axial movement of the screw on the locking screw.
The earless retaining ring for the hole is mostly installed in the annular groove on the inner wall of the pipe fitting. The outer diameter of this kind of retaining ring is slightly larger than the diameter of the assembly round hole. When assembling, the earless retaining ring needs to be pressed into the pipe fitting. Since the inner wall of the pipe fitting is relatively smooth, the earless retaining ring is easily skewed in the pipe fitting. It needs to be adjusted several times before entering the annular groove, and the assembly efficiency is low.
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