What Is a Hand Lever?

Tie rods are used to pre-tighten the combination. The structure of the tie rod, the selection of the pre-tightening force, and the arrangement of the shoulders, etc., have a large effect on the overall dynamic characteristics of the rotor. There is often a kind of structure on the building materials, and there are many building structures or materials that will be built into the tie rod type. Such as single-layer cylindrical reticulated shell, diffraction grating scribing machine, etc.

In the static state, there is an installation gap between the shoulder of the gas turbine tie rod and the hole of the disk tie rod. When working in a high-speed environment, the tie rod is bent and deformed by the centrifugal force, and the shoulder is in contact with the tie rod hole. At this time, the shoulder is subjected to a large squeeze. The shoulder can be regarded as a fixed hinge. The tie rods in between are regarded as statically indeterminate and simply supported beams. From the deflection curve of the beam in classical material mechanics approximate differential equation mouth 41 and the boundary conditions of the simply supported beam model in this paper, the maximum deflection of the tie rod between the two shoulders is obtained, and the deformation of the tie rod is proportional to the fourth power of the span Z. It is inversely proportional to the fourth power of the diameter d of the tie rod. The improvement of the structure of the tie rod from the perspective of strength is mainly to effectively reduce the deformation of the tie rod and the stress of the tie rod. Because the way to increase the diameter d of the tie rod is limited by the radial and circumferential space of the wheel disk, a reasonable increase in the number of shoulders, thereby reducing the shoulder distance Z of the tie rod, should be to improve the structure of the tie rod, reduce the deformation of the tie rod and Optimal direction of stress. ^[1]

In the low-speed area, the shoulders of the tie rods are not all in contact with the tie rod L on the wheel. At this time, the larger the static installation clearance, the higher the maximum equivalent stress value of the tie rods. After reaching the turning speed, all the shoulders are connected with the tie rod holes. Contact; in the middle speed region, the maximum equivalent stress of the tie rod slowly rises with the increase of the rotation speed, and does not change with the amount of static installation clearance; after entering the high speed region, the shoulder at the end of the tie rod occurs due to the external limitation of the countersunk head The large warpage makes the maximum equivalent stress value of the tie rod increase rapidly with the increase of the rotation speed. The purpose of dividing the speed region is to grasp the change of the tension of the rod in each speed region, and at the same time, it is convenient to set the operating speed of the rotor so that it is in a lower stress state. ^[1]

Before the limit load is reached, the strain of the tie rods is small. The tie rods in the first and third rows are basically in the elastic working stage. The restraining effect of the tie rods on the steel tube wall is relatively small. The strain developed rapidly, and soon reached yield, the curve was curved, and there was a longer horizontal section, indicating that the third and third rows of tie rods have a significant restraint effect on the steel tube wall. Because the first row of tie rods of the specimen are subject to the lateral constraint of the loading plate, its strain Development was slow until the test specimens were completely destroyed, and the first row of rods still did not reach yield. ^[2]

Gas turbine is a high-temperature, high-pressure gas-driven rotary machine with high efficiency, cleanliness, and safety. As the main structural form of the current heavy-duty gas turbine rotor, the combined drawbar rotor has the advantages of light weight, good cooling, easy assembly, and flexible selection of disc materials. Circumferential tie rod rotors are the most commonly used combined tie rod rotors. Each wheel disc needs to be pre-tightened and combined by tie rods. The tie rod structure, pre-tightening force selection, and shoulder arrangement will greatly affect the overall dynamic characteristics of the rotor. . The shoulder is an important structure on the circumferential tie rod of the gas turbine. Its main function is to maintain contact with the disc when the gas turbine rotates to prevent the tie rod from bending or deforming too much or causing excessive vibration. ^[1]

Concrete-filled steel tube structures have been widely used in civil engineering in recent years due to their high bearing capacity, good ductility, and good seismic performance. At present, the experimental and theoretical research of concrete filled steel tubes at home and abroad is mainly concentrated on circular and square concrete filled steel tubes, there are also some studies on rectangular concrete filled steel tubes, and research on other special-shaped concrete filled steel tubes such as L-shaped is still rare. L-shaped concrete-filled steel tubular columns are used for the corner columns, which will not expose the corners of the columns, so as to obtain more effective space for the building; L-shaped concrete-filled steel tubulars are used as the hidden columns of the composite wall to construct first, which is conducive to the construction of the complete reverse method, which can achieve good Comprehensive economic benefits. ^[2]

Diffraction gratings are the core components of spectroscopy instruments and are widely used in astronomy, medicine, biology, energy, materials, physics and chemistry. The middle step grating is a special diffraction grating with low reticle density, large blazing angle, and high diffraction order. It has the advantages of high dispersion, high resolution, full spectrum, and high efficiency. It is widely used in astronomy and ICP fields. And more and more favored by various spectroscopic instruments. At present, as the aperture of astronomical telescopes becomes larger and larger, the resolution requirements of astronomical spectrographs are becoming higher and higher, and the requirements for the area of the stepped grating and the accuracy of the grating scriber are also getting higher and higher.

The grating scriber consists of a scribe system and an indexing system. Scribing grating is a parallel, periodic relief structure extruded and polished by the diamond cutter on the grating aluminum film under the coordinated motion of the two systems of the scriber. The three-dimensional model of the double-rod structure scoring system is shown in Figure 1. It is mainly composed of a constant velocity cam, a lower push rod, a tension spring, an adjustment knob, a swing lever, an upper push rod, a double-rod system, a saddle slider, a glass guide and a knife. Bridge base and other components. The constant velocity cam is connected to the scoring motor. The lower push rod converts the rotary motion of the motor into the reciprocating linear uniform motion of the lower push rod under the action of the constant velocity cam and the tension spring, and then the upper push rod is driven by the swing rod to push up. The rod is connected to the saddle-shaped slider through a pulling rod structure, and drives the knife holder mounted on the saddle-shaped slider to carry the reciprocating uniform speed along the quartz guide rail. By adjusting the position of the knob, the stroke of the push-pull rod can be changed, and then gratings with different groove lengths can be scribed. The design index of the scriber is to scribe large-area mid-step gratings. The design index of the scriber system is: the groove length is 400mm, and the accuracy of the scriber system in the indexing direction is 5-10 nm. ^[3]

China's greenhouse structure generally adopts the light steel structure frame form. If the long span is excessively pursued and the traditional method is used to calculate the stability of this light steel structure, it will easily lead to excessive steel consumption, which is not economical and practical. In recent years, single-layer reticulated shells have been widely used in greenhouse construction due to their relatively reasonable stresses, large structural rigidity, and large spanning capacity, as well as their non-pillarized space and attractive appearance. The most common grid forms of single-layer reticulated shells include two-way grids and three-way grids. From the perspective of structural weight and daylighting, two-way grid-type reticles are better than three-way grid-type reticles, but two-way grids The in-plane and out-of-plane stiffness of the reticulated shell is relatively low. How to enhance the stiffness of the two-way grid-type reticulated shell has become a concern of scholars. Previous studies have mostly used rods at the two diagonals of the two-way grid to enhance its surface. Internal rigidity, or to improve the overall stability performance through the cable method, but the design of single-layer cylindrical reticulated shells with rods outside the surface is rare, and currently there is no such rod-type single-layer cylindrical reticulated shells used in greenhouse construction Engineering example. ^[4]

Trolley introduction

Tie is a special term for basketball. It is the action after jumping to avoid the block. ^[5] This action combines both difficulty and aesthetics, and is an advanced basketball technique.

The drawbar jumps with a jumper, and then someone blocks it, and then changes the action in the air. For example, the ball is brought back to the chest, and then changes to a layup. The change of the opponent of the block is generally less than the change of the action. A good way to avoid blocks.

Trick Action Skills

The drawbar requires extremely strong waist strength and at least a relatively strong bounce

Kobe draws a layup

(You can also do the drawbar without bouncing, but because of the short air time, the drawbar action must be completed faster and in a shorter period of time. The action looks awkward and not ornamental!)

The rod can avoid the block, but don't pull the rod all the time because:

First, as long as you are not playing streetball, basketball goals are fine. Do nt try to be handsome and keep pulling. Others will think that you are pretentious and also waste your physical strength. No one defends, it's a shame if you don't pull the bar alone.

Second, the twisting movement in the air is more dangerous, especially easy to be injured in fierce physical confrontation!

Trolley development process

The earliest drawbar shot was Chamberlain. He could do this action, but it was not real. Later, Iceman George Gwen improved the action and beautified the action. Later, Dr. J also used the drawbar to lay the basket from the distance. Both the upper and the flying heights have been substantially improved, giving a gliding visual impact. Since then, more and more players who can master this movement have been promoted by Jordan. The difference between Jordan and Jordan is that distance and The flying height is not much different than that of Dr. J, but the fake action in front of Jordan makes the opponent not expect him to pull the rod, so from the screen it appears that Jordan's pull rod is even more shocking. He used to have four defenders on the left side of the basket Take off from the wall of people to fly to the right side of the basket to complete the lever action, which is a classic!

The NBA's draw masters are: Michael Jordan Allen Iverson Tracy McGrady Kobe Bryant Derrick Rowans Carter and others.