What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Anchor bolts are also known as stiffened anchor plate anchor bolts, welded anchor bolts, anchor claw anchor bolts, rib plate anchor bolts, anchor bolts, anchor screws, anchor wires, etc. It is specially designed to be buried in the concrete foundation and used as the base for fixing various machines and equipment. Figure 7 anchor bolts are the most commonly used anchor bolts. It is generally made of Q235 steel, with high strength using Q345B or 16Mn material, and also using 40Cr material to process 8.8-strength products, and occasionally using secondary or tertiary rebar. Anchor bolts are divided into wool, thick rod and thin rod. The wool material is the raw material steel, which is directly processed from round steel or wire without modification; thick rods or called A-type, thin rods or B-type, are processed from steel modified into the corresponding required rod diameter. Welded anchor bolts are made of single-headed bolts welded with stiffened iron plates. Its anti-pulling ability is strong. According to the different conditions of use, it can reach 3.6, 4.8, 6.8, 8.8 and other grades respectively. The tensile capacity of 3.6 grade 7-shaped anchor bolts is the tensile capacity of the steel itself. The tensile strength of anchor bolts directly processed from Q345B or 16Mn raw materials can reach a tensile strength of 5.8. The tensile strength of grades 4.8, 5.8, 6.8 and 8.8 refer to the provisions on mechanical properties in GB/T3098.1.
In specific implementation, the axial three-dimensional shape of the nut and the screw head is in the shape of a pentagonal frustum, the elastic surface of the screw is parallel to the center line of the bolt, and the upper contour line is arc-shaped; the screw can be full or partial thread; the top of the screw head The shape is round.
Rivets are widely used in the fixing of product components, and the process of inserting rivets into products is currently mostly done by manpower. However, relying on manpower to insert rivets has low automation and low efficiency, which is not conducive to large-scale Production.
Existing wood screws are composed of a threaded portion with a tapered angle and arranged along a tapered stem and a screw head. The head of the screw can be a countersunk head, hemispherical, or other shapes, and the head of the screw has a groove that fits with the tool, a word groove, and a concave cross groove. The taper angle of existing wood screws is either 45 degrees or 60 degrees, and the front end of the taper angle is a pointed point formed by a rotating thread. The existing wood screws have the following three deficiencies in use. Because the taper angle is 45 degrees or 60 degrees, and the thread angle is 71 degrees, the resistance when entering the material is relatively large, so the existing wood screws are manually screwed. It is difficult to screw in, especially when it is used for hardwood materials, and it often happens that the groove of the screw head is screwed out; A large lateral moment will be formed when the screw is screwed, which is prone to the problem of deviation from the position; in addition, because the existing screw is tapered, it will be subjected to both radial force and axial force when entering the material, and its stress state It is more complicated, so it is easy to cause the cracked wood material to burst, and even cause the material to have longitudinal cracks and be unusable.
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