What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Yueluo relates to a self-tapping screw according to the preamble of claim 1. A self-tapping screw is known from EP0623759B1, the ratio of the outer diameter to the smaller diameter of the self-tapping screw is about 1.25-1.5, the ratio of the outer diameter to the pitch lead is about 1.5-1.6 and the thread The flank angles of , are < 50° and ≥ 35°. EP0433484B1 proposes a self-tapping screw whose thread is provided with cutting teeth of approximately arcuate design, and the cutting edge and the thread crest are at the same horizontal position and are set in opposite directions. One purpose of Yueluo is to realize a general type of self-tapping screw so that it can be screwed particularly easily into holes drilled in concrete or other materials such as bricks and the like. According to Yueluo, this object is achieved by the features in the characterizing part of claim 1, and surprisingly, it has been found that the parallel arrangement of the flanks, ie with a flank angle of about 0°, will make screwing particularly easy when screwing in , especially if the diameter of the hole varies within an allowable tolerance. One reason may be due to the fact that there is no lateral pressure on the material screwed into the thread, even if threads of different depths are cut in concrete or other materials such as brick, chipped plywood, or hardwood. The thread cuts into the material over its entire width by cutting grooves. In particular according to the embodiment of claim 3 the material cut out when screwing in the screw can be discharged without any accumulation, the dependent claims reflecting many advantages of further embodiments.
Screws and bolts are common connecting fasteners. The diameter of the thread is as small as less than one millimeter and as large as several hundred millimeters or even larger. The vast majority of threaded connections are pre-tightened during assembly in order to enhance the rigidity, tightness, anti-loosening ability of the connection and prevent the sliding of the bolted connection under lateral load. The pre-tightening force is determined according to the force of the bolt group and the working requirements of the connection. For important threaded connections, the preload must be measured and controlled.
At present, in the power industry, for the fixing of terminals, most of the terminals are directly locked to the fixing screws using U-shaped clips. However, since the contact surface often cannot reach the level of flatness, it will cause difficulties in locking, and it will take a long time. Easy to loose and fall off. Although the use of spring clips is effective, due to the influence of its own width, the use of spring clips is not very extensive. Contents of the utility model The purpose of Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. is to provide an automatic locking screw for fixing the U-shaped clip. In order to achieve the above purpose, Yueluo adopts the following technical solutions: an automatic locking screw. From bottom to top, there are screw head, screw rod and nut with external thread. The screw rod is a hollow screw rod, and the hollow screw rod is on both sides. Long holes are respectively provided, the width of the long holes is smaller than the inner diameter of the hollow screw rod, a spring is arranged in the inner cavity of the hollow screw rod, the upper end of the spring is provided with a plug, and the two wings of the plug protrude out of the hollow screw rod through the long hole. The spring described by Yueluo is not less than the length of the hollow screw rod in the free extension state. The distance between the two wings of the plug described by Yueluo is greater than the diameter of the nut. Yueluo adopts Guangdong Yueluo Hardware Industry Co., Ltd., which can easily realize the automatic locking of the U-shaped clamp, and can be adjusted according to the thickness of the U-shaped clamp to ensure the close contact between the U-shaped clamp and the connecting screw.
Yueluo Guangdong Yueluo Hardware Industry Co., Ltd. provides a rivet-oriented positioning riveting tool to overcome the shortcomings of the existing technology. The rivet is placed on the tool, and then placed in the riveting machine together with the product for riveting. In the same way, the scrap rate is reduced and the production efficiency is greatly improved. In order to achieve the above purpose, a rivet guide positioning riveting tool is designed, which includes a riveting positioning block and a riveting lower die, which is characterized in that a riveting positioning block is arranged above the riveting lower die. The riveting positioning block includes a positioning pin and a rivet yielding hole, a through hole is arranged in the center of the riveting positioning block, a rivet hole is arranged on one side of the through hole, and a number of positioning pins are arranged on the riveting positioning block around the through hole. . There are five positioning pins. The riveting lower die includes a countersunk head screw hole, a rivet guide block and a positioning hole. The riveting lower die is a stepped module. The left side of the riveting lower die is provided with a countersunk head screw hole, and the right side of the riveting lower die is provided with a countersunk head screw hole. The guide block is provided with several positioning holes on the riveting lower die located in front of the guide block. There are two positioning holes. The center of the guide block is provided with an escape hole. Compared with the existing technology, Guangdong Yueluo Hardware Industry Co., Ltd. has a rivet-oriented positioning riveting tooling. The rivets are placed on the tooling, and then placed in the riveting machine together with the product for riveting, which solves the problem of manual knock-in. The efficiency is low, and the riveting can be riveted without deviation without manual righting during riveting, so that the quality of the products produced is the same, the scrap rate is reduced, and the production efficiency is greatly improved.
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