Precision Screw Research Articles

Three-dimensional printing technique aids screw insertion into the sustentaculum tali of the internal fixation of intra-articular calcaneal fractures

IntroductionTreating complex calcaneus fractures remains challenging. This study evaluated the influence of 3D printing and simulation on precision screw insertion into the calcaneus sustentaculum tali (ST). Hypothesis3D printing and simulation improve the treatment for calcaneal fracture. Patients and methodsThis retrospective cohort study included 85 patients admitted with 93 Sanders type II–IV intra-articular fractures from January 2015 to June 2020. Multi-slice computed tomography (MSCT) images were used in the conventional group, and MSCT data were used to construct a 3D model of the calcaneus to simulate screw insertion and verify parameter accuracy in the 3D group. ResultsThe designed parameters (upward and backward oblique angles and screw-path length) were similar to the actual values in the 3D group (p=0.428,0.287,0.585) but not in the conventional group (p=0.01,0.002,0.023). The Maryland foot functional score, accuracy rate, and average screw number were higher and operative time was shorter in the 3D group (p=0.005,0.007,0.000,0.000). DiscussionPreoperative simulation using the 3D printing model helped guide the screws into the ST more accurately, lending better-quality treatment for Sanders type II–IV calcaneal fractures. Level of proofIII; Retrospective case-control study.

Analytical modeling of material removal mechanism in dry whirling milling process considering geometry, kinematics and mechanics

Whirling milling is a promising machining process that couples the tools and workpiece motions while both conventional turning and milling are carried out, which is widely used for machining precision screw parts made of hard materials, such as titanium alloy, quenched steel, etc. The challenge is due to the complex kinematics can lead to the varying tool-workpiece engagement and undeformed chip geometries which affect significantly the mechanics, quality and productivity. The existing studies are mainly based on the simplification of process mechanism to study the mechanics and quality however, the material removal mechanism and influences of cutting parameters are still not well understood. This paper presents an analytical approach to investigate the material removal mechanism in whirling milling, thus to predict the undeformed chip geometry, material removal rate (MRR), cutting forces and form errors. The varying tool-workpiece engagement geometry along the cutting trajectory is identified to model the varying undeformed chip geometry including instantaneous chip thickness, cross-section area and tool-workpiece contact length. The form errors including circularity error, scallop height and surface roughness are defined and predicted as a function of tools and workpiece motion, position and dimension parameters. The whirling milling experiments were conducted to validate the analytical modeling approach with the largest error 11.3% and average error 13.0% for force and surface roughness prediction, respectively. The influences of cutting parameters on surface roughness and MRR are finally analyzed to explore the potential of productive cutting conditions for whirling milling.

The Design and Analysis of the Actuator with Long Stroke and Micro-Displacement

In this paper, a new actuator with nanoscale micro-displacement is reported. The actuator not only can achieve a large stroke and nanoscale positioning accuracy, but also has the advantages of compact, low cost, high reliability and a single control system. The drive is controlled by a single power, and it consists of stepper motor, harmonic gear reducer, screw and the guide rail. The stepper motor is controlled by the pulse train and the harmonic gear reducer has high precision and small hysteresis. The precision screw converts the rotary motion of the stepper motor into linear displacement, and the plunger pushes the target in nanoscale motion accuracy through the guide rail finally.

Screw Inspection Optimized System Design and Implementation

In machinery and equipment manufacturing industry, screw is an important part. Not only as a precision screw precision transmission components, but also commonly used for precision measuring devices. Precision screw itself directly affects the accuracy of precision machine tools and precision measuring instruments for transmission, positioning precision and accuracy, and thus the processing and inspection of precision screw is higher demanded. Traditionally, screw inspection is usually done by manual and the quality of inspection is not high, with very low inspection efficiency. To solve these problems, optimized system for screw inspection was designed and implemented. Using the Quartile range method in Statistics to remove outliers, and with the help of kalman filter, systemic error is got rid of. With these methods, raw measurement data is analyzed and processed, and inspection report is generated. The efficiency of screw inspection is highly improved.

A precision translation stage for reproducing measured target volume motions

The development of four‐dimensional (4D) imaging, treatment planning, and treatment delivery methods for radiation therapy requires a quality assurance device that can reproduce clinical motions. Here, we present a high‐precision translation stage for testing and validating 4D techniques. These techniques may require spatial resolutions of 1 mm and temporal resolutions of 2 – 30 Hz for computed tomography imaging, electromagnetic tracking, and fluoroscopic imaging. A one‐dimensional programmable translation stage capable of reproducing idealized and measured anatomic motions common to the thorax and providing support for phantoms weighing up to 27 kg was designed and built to meet the foregoing spatial and temporal resolution requirements. The stage consists of a polycarbonate base and table, driven by an ac servo motor with encoder feedback by means of a belt‐coupled precision screw. Complex motions are made possible by a programmable motion controller that can run multiple independent control and monitoring programs concurrently on independent motion axes. Programmable input and output ports allow motion to be synchronized with beam delivery and other imaging and treatment delivery devices to within 2.0 ms. Average deviations from the programmed positions are typically 0.2 mm or less, and the average maximum positional errors are typically 0.5 mm for an indefinite number of parameterized breathing motion cycles during reproduction of measured target volume motions for several minutes.PACS number: 87.66.Xa

高精度ファンリブ型メッシュ展開鏡面

This paper describes the performance of fan rib type highly accurate, highly reproducible mesh deployable reflector with precision screw type adjustment element for surface drawing and motor and link type deployment system. Surface error and its reproducibility for repeated deployment decreased less than 1/2 of previously developed fan rib type mesh reflector with spring type deployment system. No periodic distortion which corresponds to rib arrangements can be seen and thus mesh reflector with very low gore lobe and side lobe characteristics, which is very useful for frequency reuse, is achieved in C band. This paper also presents measured higher order passive intermodulation (PIM) products of mesh developed and used for this deployable reflector with the mesh tension as a parameter.

A Multifunction Thermomechanical Analyzer for Fibers—Its Constructional Features and Applications

The construction of an improved model of TMA for fibers is briefly described. Two special features are: use of an electronic balance for measuring force and use of a precision screw driven by a servo-step motor for measuring length. Besides the usual thermomechanical measurements, the use of the instrument as a research tool for a number of purposes like fiber texture, orientation, heat treatment, and so on has been amply illustrated.

A computer-controlled multichannel micropipetter

A multichannel micropipetter was developed capable of pipetting as little as 1 μl with a reproducibility of better than ±2% and an accuracy of ±0.5%. The micropipetter consists of a precision syringe to which 13 individually valved fluid channels are connected as a bundle of segments spreading out radially from the tip of the syringe to pinch valves and further to fluid interfaces consisting of steel tubing sections for uptake or dispensing of fluid. A stepping motor drives the piston of the measuring syringe by means of a precision screw. Motor and valves are under computer control. Low dead volume (internal volume, ca. 1 μl/channel; external volume, 0.3 μl/cm of tubing), and the absence of internal valving parts ensure low cross-conamination (ca. 0.1%). These features together with the versatility provided by the large number of independent channels and the automatic operation make the instrument suitable for pipetting multicomponent mixtures in the general biochemistry laboratory (for enzyme kinetics and complex reactions) as well as in specialized routine applications (clinical diagnostics and radioimmunoassay).

Pumping systems for use with flow calorimeters

Six liquid flow generators of different types are described. They have been developed principally for use with liquid flow calorimeters which require a continuous supply of liquid over the space of an hour at an optimum flow rate of 1.5 cm3 min-1 which is constant to at least 1%. Three simple pressure-driven generators which meet with this requirement are described. A precision hydrostatic flow generator which will supply 900 cm3 of liquid at a rate which is constant to better than 0.1% is also described. Details of the design of a precision screw- driven piston and cylinder pump are given. This pump will supply two liquids simultaneously, each at a flow rate which is constant to better than 0.1%. Alternative piston and cylinder assemblies which allow very small quantities of liquid to be pumped at very slow flow rates are also described.

Application of holography to detect precision screw errors and its associated problems

Application of holography to detect precision screw errors and its associated problems

親ねじを用いる歯形測定機

The tester reported in this paper employs the permanent base-circle disk method and is designed for fine pitch gears. In making the linear travel of the feeler carrier equal to the circular travel at the base circle of the measured gear, the feeler carrier is linearly moved by a precision screw. The straight edge which rolls on the base-circle disk is separated from the feeler carrier and is driven by another precision screw. A gear train connects these precision screws having a speed ratio of dg/Ds where dg is the base diameter of the work gear and Ds is the diameter of permanent base disk.The deviations from the true involute are registered by an electrical recording system.Some of fine pitch gears are measured by this tester.

Remote balance for accurate weighing in high radiation environment

This balance is used at Experimental Breeder Reactor II to weigh radioactive fuel pieces. The weighing and handling must be done in a shielded cave by remote control. A commercial balance was modified for this use and outfitted with electronic controls and digital readout. The beam balance has a poise weight positioned by a precision screw which is driven by a stepping motor. The remote readout is coupled to a mechanical counter driven by another stepping motor which operates synchronously with the balance motor. The balance is accurate to ± 2 g over a range from 100 to 18000 g and has been in operation for over a year at gamma radiation levels as high as 10 6 R/h.

A digitized microphotometer and automatic reduction of spectroscopic data

The Jarrell-Ash precision screw microphotometer (Model 23–500) has been equipped with digitized output. The microphotometer itself has a David W. Mann 20 cm lead-screw, accurate to 1 micron. The digitizer is a product of Wang Laboratories.

A computer program for the transformation of lunar observations from celestial to selenographic coordinates

A program has been devised which is suitable for mapping observations onto the nighttime surface of the Moon. It can be extracted from the present paper without being understood in detail, and familiarity with computer programming is not required. The basic data used in the program are the universal times, right ascensions, and declinations of points of interest on the Moon which are recorded from the telescope's coordinate circles and a Greenwich clock. Focal plane precision screw coordinates may be substituted if desired. In addition, for part of these points, selenographic coordinates are input. This subset, necessarily contained on the sunlit portion of the Moon, is used as a set of standards from which to derive a function describing the translation of the center of the Moon on the celestial sphere relative to the vernal equinox. The balance of input data are limiting conditions which may be read directly without interpolation from the ephemeris. Results are presented from test data which show an average geodesic residual of 0.5 degrees fairly independently of which of several versions of the computer program are used. The error is thus random gear train error in the telescope, which can be expected to decrease in future applications inasmuch as the test data were gathered when the telescope installation was new and not yet tightly adjusted.

Six-Meter Focal Length Ebert-Type Infrared Spectrograph Part II Precision of Measurements

A semi-empirical procedure for determining spectral positions to an accuracy of ±0.005 cm−1 in the near infrared region is discussed. The infrared spectra have been scanned by rotating the grating with the help of a precision screw. It is believed that the techniques discussed enable the measurement, with the above precision, of many infrared lines in one day.

A Study on Precision Screw Cutting by Using Feedback Control

In conventional precision screw cutting, the pitch accuracy of cut screw mainly depends on the lead screw of the screw cutting lathe. The lead screw serves as the accurate feeder of a cutting tool, on the other hand it is worn out by the heavy load of the carriage. Accordingly, the pitch accuracy of the lead screw will be degraded rapidly. While, by additional installing a precision master screw and a feedback controller besides the ordinary lead screw, the error caused by the driving screw will be eliminated and the high accuracy will be held for a long time. This paper is the report of the control effect in our screw cutting lathe, which is equipped with the control system based on the above mentioned principle. The screw cutting accuracy of our lathe being degraded to 80μ/300mm, was improved to 17μ/300mm by using the feedback controller, and further it attained to 4μ/300mm by using the compensation cam at the same time.

A High Resolving Power, Curved-Crystal Focusing Spectrometer for Short Wave-Length X-Rays and Gamma-Rays

Description is given of a transmission-type, curved-crystal focusing spectrometer for short wave-length x-rays, and gamma-rays having a dispersion of 1.186 x.u. per mm at short wave-lengths. The spectrometer utilizes the (310) planes of quartz in a crystalline plate of dimensions 80×70×1.0 mm curved cylindrically to a radius of two meters. High luminosity is obtained since the useful aperture in the crystal holder has an area of 10 cm2 and subtends 0.00025 stereradians at the focus. It also affords high resolution since by photographic tests with x-rays the curved plate has been shown to focus a specified x-ray wave-length to within 0.06 mm of the same position on the focal circle for all parts of its useful aperture and over the entire operating wave-length range. The geometry of the mechanism permits absolute measurements with a precision screw of the sine of the Bragg angle on both sides of the reflecting planes, affording a wave-length range which includes at longest wave-lengths the K-spectrum of silver and goes down to zero wave-lengths. For short wave-length gamma-rays the source is placed at the focus. A multiple-slit collimator of tapering die-cast lead partitions spaced apart with tapering separators, is used at short wave-lengths to transmit the monochromatic diffracted beam and absorb the directly transmitted and scattered heterogeneous beam. The present collimator limits the spectrum that can be studied to a shortest wave-length of 7. x.u. corresponding to 1.75 Mev. The intensity of the diffracted beam is to be measured with a special multi-cellular G. M. counting tube of high efficiency, provided with a number of thin lead partitions through which the beam passes successively. In photographic spectra made with this instrument the tungsten and also the silver Kβ1β3 doublet is completely and clearly resolved. Reproductions of such photographic x-ray spectra are shown in which the line breadths have substantially the natural breadth. Fluorescence spectra of silver have been made in 10-minute exposures. A companion paper gives the all-important precision technique of generating the curved cylindrical stainless steel clamping blocks for the crystal.