First, multiple-choice questions (single choice) (80 points)
1. Tempering is (00). A, quenching+high temperature tempering B, quenching+medium temperature tempering C, quenching+low temperature tempering D, carburizing+quenching
2. When the standard twist drill bit grinds the chip separation groove, it grinds the chip separation groove at (00). A, rake surface b, auxiliary flank c, base surface d and flank.
3. The national standard stipulates that the major diameter of external thread should be drawn (00). A, dotted line b, thick solid line c, thin solid line d, dotted line
4. Mechanical transmission is an energy transmission device (00) composed of pulleys, gears, shafts and other mechanical parts.
A, conversion b, transfer c, transportation d, exchange
5. In the chain drive, the chain and wheel are seriously worn, and the method (00) is used to repair them.
A, wheel repair b, chain repair c, chain and wheel repair d, chain and wheel replacement
6. When tightening the group nut pattern with circular or square arrangement, it must be (00).
A, symmetrically; B, symmetrically proceeding from two sides; C, from outside to inside; D, something is wrong.
7. Incorrect mutual position of pulleys will lead to uneven belt tension and rapid wear. The measurement method of (00) is a long ruler.
A, tension b, friction c, center distance d, none of them.
8. Spheroidizing annealing is generally suitable for (00).
A, high-quality carbon structural steel B, alloy structural steel C, ordinary carbon steel D, bearing steel and alloy tool steel
9. Hydrostatic bearing relies on liquid (00) to balance external load. A, flow b, static pressure c, dynamic pressure d, weight
10. When lifting, the hook should be perpendicular to the center of gravity, and when the rope is perpendicular to the ground, it should generally not exceed (00). A, B, C, D, 50
1 1. The wear caused by the gradual formation of particles on the moving surface metal is called (00).
A, fatigue wear b, sand wear c, friction wear d, consumption wear
12. The assembly sequence of worm drive mechanism should be determined according to the specific situation, which should be (00).
Get an example. Install the worm first, then the worm wheel B, then the worm wheel C, then the bearing, then the worm D, then the worm and then the bearing.
13. When marking the deformed workpiece, it is required that the center of gravity of the workpiece or the combined center of gravity of the workpiece and fixture should fall within the bearing surface, otherwise the corresponding (00) must be added. A, support plate B, support nail C, auxiliary support D and V-shaped block
14. When drilling holes on materials with high plasticity and toughness, it is necessary to strengthen lubrication, and appropriate (00) can be added to the cutting fluid.
A, animal oil and mineral oil b, water c, emulsion d and linseed oil
15. Wires passing through doors and windows and other (00) wires shall be sheathed with magnetic tubes. A, plastic pipe b, wood c, aluminum d, combustible materials
16. Conical interference connection requires that the contact area of fit should be greater than (00) to ensure the stability of fit.
a、75% B、80% C、85% D、90%
17. When choosing a file, the file (00) should be suitable for the shape of the machined surface of the workpiece.
A, size b, thickness c, old and new d, cross-sectional shape
18. Analyze the shape of the part and make sure that the direction of the front view is to draw the part drawing (00).
A, step 1 B, step 2 C, step 3 D and step 4.
19. Draw a circle bisector or an unequal bisector on the workpiece with (00).
A, dividing head b, marking needle c, marking gauge d and three-dimensional marking
20. The method of preparing process specification is (00) first.
A, analyze product B, determine organizational form C, determine assembly sequence D, and divide working procedures.
2 1. In scraping, the flat plate is often produced by positive grinding (00).
A, plane distortion phenomenon B, the research point can not meet the requirements C, one head is high and the other is low D, uneven.
22. In general, in order to simplify the calculation, when r/t≥8, the neutral layer coefficient can be calculated by (00).
a、X0=0.3 B、X0=0.4 C、X0=0.5 D、X0=0.6
23. When choosing the wedge angle, try to take the value of (00) on the premise of ensuring sufficient strength.
A, smaller B, larger C, average D, whatever.
24. The contactor is a kind of (00) electromagnetic switch. A, indirect b, direct c, non-automatic d, automatic
25. After the pulley is installed on the shaft, check its end face runout with measuring tool (00). A, ruler b, dial indicator c, protractor d, ruler or pull rope
26. The parts are biased in radial position, but the inertia force will not pass through the center of gravity of the rotating parts. This imbalance is called (00).
A, static imbalance B, dynamic imbalance C, static balance D, dynamic balance
27. The belt drive is driven by (00) between the drive belt and pulley.
A, force b, tension c, friction d, elasticity
28. The part not included in the dividing head structure is (00).
A, a shell b, a spindle c, an indexing mechanism, an indexing disc d and a gear.
29. Atomize the fuel into finer particles and distribute them in the combustion chamber. This device is called (00).
A, fuel injection pump b, fuel injector c, filter d and governor
30. The interference connection depends on the (00) after the container is mated with the container to realize the fastening connection.
A, pressure b, tension c, interference value d, friction force
3 1. In chain drive, 2%L is suitable for chain (00). A, sag b, deflection c, tension d, tension
32. According to the fuel used, internal combustion engines are divided into (00) gasoline engines, gas engines and biogas engines.
A, kerosene engine b, diesel engine c, reciprocating piston d and rotary piston
33. The positioning of rectangular workpieces should be distributed on the support points of the guide datum (00) and should be on the same plane.
A, a b, two c, three d and four.
34. When bending a pipe, the minimum bending radius must be greater than (00) times the diameter of the pipe. a、2 B、3 C、4 D、5
35. The main specifications of the dividing head are indicated by (00).
A, length b, height c, height d from the center line of the top (spindle) to the bottom surface, and the maximum diameter of the clamped workpiece.
36. In order to improve the machinability of low carbon steel, (00) treatment is usually adopted.
A, complete annealing B, spheroidizing annealing C, stress relieving annealing D and normalizing
37. There are two types of pin connection: cylindrical pin connection and (00) connection. A, taper pin b, round pin c, flat pin d, taper pin
38. The fine file must use (00) to make the file mark straight and the texture consistent. A, cross file b, rotary file c, cutting file d and advancing file
39. When sawing hard materials or workpieces with small cross sections, a (00) saw blade should be used. A, hard teeth b, soft teeth c, coarse teeth d, fine teeth
40. Using (00) to make the preload reach a given value is the control torque method.
A, socket wrench b, dynamometer wrench c, universal wrench d, professional wrench
4 1.(00) is not only used for connection under impact vibration or variable load, but also used for adjusting mechanism because of its small pitch, small helix angle and good self-locking.
A, coarse thread b, pipe thread c, fine thread d, rectangular thread
42. The tap structure consists of (00).
A, cutting part and handle part b, cutting part and calibration part c, working part and calibration part d, working part and handle part
43. The main working face of the document refers to (00).
A, upper and lower surfaces b, two side surfaces c, all surfaces d and a top surface with a file.
44. Flat files, square files, round files, semi-circular files and triangular files belong to category (0). A, special file b, assorted file c, ordinary file d, plastic file
45. The pin connection in machinery is mainly used for positioning, connecting into a locking piece, and sometimes it can also be used as a (00) piece of safety device.
A, transmission B, fixing C, positioning D, and overload cutting
46. Induction heating surface quenching, the higher the current frequency, the greater the depth of hardened layer (00). A, deeper B, shallower C, constant D, bigger.
47. Draw a hexagon on the disk, and the graduation formula should be (00). a、20/Z B、30/Z C、40/Z D、50/Z
48. The internal combustion engine is a heat engine that converts thermal energy into (00). A, mechanical energy b, kinetic energy c, motion d, potential energy
49. The main movement of grinding is (00). A, grinding wheel circular motion b, workpiece rotation motion c, table motion d, grinding wheel rack motion
50. The algebraic difference between the maximum limit size of the hole and the minimum limit size of the shaft is a positive value called (00).
A, clearance value b, minimum clearance c, maximum clearance d and minimum interference.
Cams made of 5 1. 15 steel require high surface hardness and high center toughness, so (00) heat treatment process should be adopted.
A, carburizing+quenching+low temperature tempering B, annealing C, tempering D and surface quenching
52. The spindle axis of the indexing head can be upward (0) and downward 10 relative to the table plane. a、 10 B、45 C、90 D、 120
53. When the workpiece positioning datum and the positioning hole are long, the positioning of the outer cylindrical workpiece in the sleeve hole can be limited to (00) degrees of freedom.
A, two actions b, two rotations c, two actions two rotations d, one action and one rotation.
54. The rake angle of a standard twist drill is the included angle between the rake face and the (00) cutting plane.
A, base surface b, main section c, column section d, auxiliary side surface
55. Check the backlash of worm drive. The demanding method (00) is used for measurement.
A, feeler gauge B, dial indicator C, pressure lead D and vernier caliper
56. In order to reduce vibration, the tapered countersunk hole modified with twist drill is generally ground to double rake angle (00).
a、αο=0 ~5 B、αο=6 ~ 10 C、αο= 10 ~ 15 D、αο= 15 ~20
57. The basic principle of disassembly is that the disassembly sequence is opposite to (00).
A. assembly sequence b, installation sequence c, assembly sequence d and adjustment sequence.
58. After the high-speed gear is installed on the shaft, check the balance to avoid working (00).
A, loose b, fall off c, vibration d, aggravating wear.
59. The partial cross-sectional view uses wavy lines as the dividing line between the cut and uncut parts, and the thickness of wavy lines is the thickness of thick solid lines (00).
A, 1/3 B, 2/3 C, same d, 1/2.
60. In the contact area, the method of removing the convex part of the tooth surface by pulse discharge to gradually expand the contact area is called (00).
A, load running-in b, electric spark running-in c, grinding d and scraping.
6 1. The executive part in the hydraulic system refers to (00).
A, hydraulic pump b, hydraulic cylinder c, various control valves d, oil pipeline, oil tank, etc.
62. The mating surface of interference connection is mostly cylindrical, and there are also conical surfaces or (00).
A, square b, rectangle c, cube d, other shapes
63. According to the specified technical requirements, the process of combining several parts into parts or combining several parts and parts into a machine is called (00).
A, component assembly B, general assembly C, component assembly D, assembly
64. The factors that affect the accuracy of gear transmission are gear machining accuracy, gear accuracy grade, gear pair backlash requirements and (00).
A, tooth profile accuracy B, whether the installation is correct C, transmission smoothness D, gear pair contact spot requirements
65. The symbol of the position tolerance item is (00). a 、- B、○ C 、= D、⊥
66. The working medium of hydraulic transmission has a certain pressure (00). A, gas b, liquid c, mechanical energy d and electric energy
67. The hydraulic oil commonly used in hydraulic transmission is (00). A, gasoline b, diesel c, mineral oil d, vegetable oil.
68. Use the starting equipment to start the motor stator winding with appropriate voltage (00), and then restore the voltage to the rated value after starting. This is called step-down starting. A, increase B, decrease or increase C, decrease D, and adjust.
69.(00) When the coupling is working, a small amount of radial deviation and skew are allowed for the two shafts.
A, flange type B, universal joint C, slider type D and cross groove type
70. The metal plate is wavy around, and the hammering point should be (00) when using the extension method to find peace.
A, from one side to the other side b, from the middle to all sides c, from one angle d, from all sides to the middle.
7 1. The commonly used methods of product assembly include complete interchange assembly method, selective assembly method, repair assembly method and (00).
A. adjustment assembly method b, direct matching method c, grouping matching method d and interchange assembly method.
72.Ry is the symbol of (00) in surface roughness evaluation parameters.
A, contour arithmetic mean deviation b, microscopic roughness+point height c, contour maximum height d, contour roughness.
73. The level is usually used to test the surface of a workpiece or the installation of equipment (00). A, vertical b, parallel c, horizontal d, tilt
74. In order to ensure the safety of machine tool operators, the voltage of machine tool lighting lamp should be selected as (0). A, 380V B, 220V C, 1 10V D and below 36V.
75. Mainly used for grinding carbon tool steel, alloy tool steel and high-speed steel workpieces, and the abrasive is (00).
A, oxide abrasive B, carbide abrasive C, diamond abrasive D and chromium oxide abrasive
76.(00) The assembly requirements of the coupling should strictly ensure the coaxiality of the two shafts under normal circumstances.
A, slider type B, flange type C, universal joint D and cross groove type
77. A complete assembly drawing includes: (1) a set of drawings; ⑵(00); (3) Necessary technical requirements; (4) Part serial number and detailed list; 5] Title bar. A, correct size b, complete size c, reasonable size d, necessary size
78. The assembly accuracy depends entirely on the assembly method of the part (00), which is completely interchangeable.
A, machining accuracy b, manufacturing accuracy c, machining error d, accuracy
79.(00) has a great influence on the roughness of holes. A, cutting speed b, bit stiffness c, bit vertex angle d, feed speed
80. The following (00) does not belong to the assembly process.
A, the assembly process is divided into working steps; B, assembly work; C, adjustment, precision maintenance and trial operation; D, painting, oiling and packaging.
8 1. The inhomogeneity of the micro-geometric shape composed of the smaller spacing and peaks and valleys of the part (00) is called surface roughness.
A, inner surface b, outer surface c, machined surface d and non-machined surface
82. The task of the coupling is to transmit torque, and sometimes (00) can be used.
A, positioning function b, changing movement direction c, safety device d, support function
83. When tapping M 10× 1.5 screw hole on medium carbon steel, the bottom hole diameter should be (00). A,10mm b, 9mm c, 8.5mm d, 7mm
84. The tooth profile angle of common thread is (00). A, 55 b, 60 c, 55 or 60 d, 75
85. Replacing the key is a common repair method for (00) wear. A, spline b, Ping Jian c, wedge key d, key
86. Maintenance of the vertical drilling motor (00) requires disassembly and cleaning of the motor as required, and replacement of 1 calcium-based grease.
A, 1 Grade B, Grade 2 C, Grade 3 D and Grade 4
87. When the stress exceeds a certain limit, the clutch that slips automatically is called (00).
A. side gear clutch b, internal gear clutch c, friction clutch d and pin clutch.
88. The gear is fixed on the shaft. When a large amount of interference is needed, the combination of (00) should be adopted.
A, tapping method b, pressing method c, hydraulic sleeve method d, impact method
89. The loose key is assembled along the length direction of the key, and the clearance between the key and the shaft groove is (00) mm..a, 1 B, 0.5 C, 0.2 D, 0. 1
90. The valve mechanism opens or closes the intake valve or exhaust valve according to the (00) timing of the internal combustion engine, so that air or combustible mixture can enter the cylinder or exhaust the exhaust gas from the cylinder. A, piston reciprocating times b, working sequence c, stroke times d, structure
9 1.(00) clearance directly affects the transmission accuracy of lead screw nut pair. A, axial direction b, normal direction c, radial direction d, tooth tip
92. Thread assembly includes (00) assembly. A, common thread b, special thread c, stud d, stud and nut, screw
93. Artificial respiration method is suitable for those who get an electric shock (0). A, there is a heartbeat without breathing B, there is no heartbeat without breathing C, there is breathing without heartbeat D, and the brain is not dead
94. When V-belt transmission is adopted, the friction force is (00) times that of flat belt. a、5 B、6 C、2 D、3
95. The steel of carburized parts is (00). a、20Cr B、45 C、T 10 D、T4
96. Wear when using electric drill (00). A, thread gloves b, canvas gloves c, rubber gloves d, cotton gloves
97. Equipment maintenance and disassembly should generally be (00).
A, first remove the inner upper part B, the outer lower part C, the outer upper part D and the inner lower part.
98. To specify the pre-tightening force of threaded connection, torque control method, twist angle control method and (00) are commonly used to ensure the accuracy of pre-tightening.
A, method of controlling workpiece deformation B, method of controlling bolt elongation C, method of controlling bolt deformation D, method of controlling nut deformation
99. When repairing equipment, you should first (00). A, prepare B, prepare repair tools C, cut off power supply D, and prepare to replace spare parts.
100. When straightening the bar, the warping caused by elastic deformation can be eliminated (00).
A, appropriately press B less, C less and D more, so as to make it reverse bending plastic deformation.
10 1. Assemblers are only allowed to wear (00) when on duty. A, sandals b, shoes c, high heels d, work shoes.
102. Basic principle of disassembly, disassembly sequence and assembly sequence (00).
A, same B, opposite C, same but different D, basically opposite.
103. When the bit diameter is greater than 13mm, the handle is generally made of (0). A, straight shank B, Morse taper shank C, square shank D and straight shank taper shank are all available.
104. cuboid workpiece positioning, with support points distributed above (00).
A, thrust datum b, guide datum c, main positioning datum d, large plane
105. When drilling with a drilling machine, the rotation of the drill bit is (00) movement. A, main B, feeding C, cutting D and working
106. The main components of vertical drilling machine include spindle gear box, feed gear box, (00) and feed handle.
A, feed mechanism b, control mechanism c, frame d and spindle
107. The main components of vertical drilling machine include spindle gearbox, feed gearbox, spindle and (00).
A, feed handle b, control structure c, rack d and steel ball joint
108. The inner dial gauge is equipped with a hairspring, and its function is (00) mm. ..
A, control the measuring force b, drive the long pointer to rotate c, drive the short pointer to rotate d, and eliminate the gear gap.
109.(00) Roundness errors usually occur in parts processed by grinding machines. A, centerless excircle b, excircle c, ordinary d, plane
1 10. The assembly dimension chain has at least (00) reduction rings and closed rings. A, ring b, increasing ring c, decreasing ring d, ring
1 1 1. When assembling the key, check the contact between the upper and lower surfaces of the key and (0) by coloring method. A, shaft b, hub groove c, shaft and hub groove d and groove bottom
1 12. When the saw blade is manufactured, the saw teeth are staggered left and right according to certain rules and arranged in a certain shape, which is called (00).
A, cutting angle b, sawing path c, sawtooth thickness d, sawing.
1 13. The purpose of directional assembly is to offset a matching size (00).
A, machining error b, assembly error c, upper deviation d and lower deviation
1 14. When the piston reaches the top dead center, the pressure in the cylinder (00) is still higher than the atmospheric pressure, and the exhaust valve is closed later, so that the exhaust gas can be discharged more cleanly.
A, air b, waste gas c, combustible gas d and carbon dioxide
1 15. When using files, you cannot (00). A, shift B, double-hand shift C, shift D and single-hand shift
1 16. Any assembly work that combines two or more parts or several parts into an assembly unit is called (00). A, component assembly B, general assembly C, component assembly D and clearance adjustment
1 17. A key point of conical friction clutch assembly is that there is enough pressure at (00) to compress the two cones.
A, B at disconnection, C at assembly, D at assembly and D at work.
1 18. There are (00) precision classes for ordinary cylindrical worm drive. a、 18 B、 15 C、 12 D、 10
1 19. When writing the limit deviation in the part drawing, the decimal points of the upper and lower deviations are aligned, and the digits after the decimal point are the same as zero deviation (00).
A, B must be marked, C is not needed, D is written, and it is represented by symbols.
120. (00) of gear teeth should be checked by coloring method. A, meshing mass b, contact point c, backlash d and contact accuracy
12 1. A motor that converts DC energy into mechanical energy and outputs mechanical torque is called (00).
A, DC motor b, synchronous motor c, asynchronous motor d, squirrel-cage motor
122. A complete assembly drawing includes: (1) a set of graphics; (2) the necessary scale; ⑶(00); (4) Part serial number and detailed list; 5] Title bar. A, technical requirements B, necessary technical requirements C, technical requirements D of all parts, roughness and form and position tolerance
123. The algebraic difference between the minimum limit size of the hole and the maximum limit size of the shaft is a positive value called (00).
A, clearance value b, minimum clearance c, maximum clearance d and maximum allowance
124. Radial sliding bearing and thrust sliding bearing are classified according to bearing (00).
A, structural form b, bearing direction c, lubrication state d, and method of obtaining liquid friction.
125. When the gasoline engine is working, each cylinder is ignited once every revolution of the crankshaft. a、 1 B、2 C、4 D、8
The worm and worm wheel of 126.(00) are perpendicular to each other. A, center of gravity line B, center line C, axis D, connecting line
127. The function of fuse is (00). A. Connection and disconnection of protection circuit B, power supply C, transformer D and control current
128. The solution of the assembly dimension chain is (00). A, look-up table method B, statistical method C, calculation method D, formula method
129. Spiral transmission machinery converts spiral motion into (0). A, two-axis speed vertical motion b, linear motion c, spiral motion d, curve motion
130. The stable operation of the shaft and its parts after assembly is the assembly requirement of (00). A, shaft group b, machine c, bearing d and gear shaft
13 1. The factors affecting gear (00) include gear machining accuracy, gear accuracy grade, gear pair backlash requirement and gear pair contact point requirement. A, motion accuracy b, transmission accuracy c, contact accuracy d, and working stability.
132. When cutting a workpiece, the higher the cutting speed, the longer the tool life (00). A, the longer B, the shorter C, the same D, it doesn't matter.
133. The requirement for the clutch is (00), which is stable and can transmit enough torque.
A, can change the movement direction b, open and close sensitively c, transmit torque d, and make the two shafts run synchronously.
134. foam extinguisher should not be placed in the (00) position. A, indoor B, warehouse C, high temperature place D, fire equipment rack
135. Yes, (00) plays the role of blending abrasive, cooling and lubrication in grinding. A, grinding liquid b, grinding agent c, grinding agent d and grinding tool
136. Common brands of high-speed steel are: (00). a、CrWMn B、W 18Cr4V C、9siCr D、Cr 12M0V
137. Large-diameter steel bars or shafts are usually straightened with (00). A, press B, hammer C, vice D, adjustable wrench
138. Includes: (1) a set of graphs; (2) the necessary scale; (3) Necessary technical requirements; (4) Part serial number and detailed list; 5] The mode of five items in the title bar is (00). A, part drawing b, assembly drawing c, development drawing d and schematic diagram
139. The loose key is assembled in the longitudinal direction, and the gap between the key and (00) is 0.1mm.. A, shaft groove b, groove bottom c, hub d, shaft and hub groove
140. Do not wear gloves when operating (00). A, drilling machine B, lathe C, milling machine D, machine tool
14 1. When calibrating the nut pair (0) with the inspection rod, in order to eliminate the installation error of the inspection rod in each supporting hole, the rotation of the inspection rod180 can be measured once and the average value can be taken. A, coaxiality b, verticality c, parallelism d, and jumping.
142. When positioning a rectangular workpiece, (00) support points should be distributed on the main datum plane and on the same plane.
A, a b, two c, three d and four.
143. The longitudinal feed and transverse feed movements of the lathe (00) are screw drives. A, polished rod b, rotation c, vertical shaft d and lead screw
144. The longitudinal feed and transverse feed movements of the lathe lead screw are (00).
A, gear transmission b, liquefaction transmission c, screw transmission d and worm pair transmission
145. The minimum rotation speed of vertical drilling Z525 spindle is (00). a、97r/min B、 1360r/min C、 1420r/min D、50r/min
146. The flatness requirement of the flat plate for inspection is 0.03, and the method (0) should be selected for processing. A, grinding B, fine planing C, scraping D and filing.
147. The main moving part of diesel engine is (00). A, cylinder b, fuel injector c, crankshaft d, thermostat
148. The drilling dies are: fixed, movable, flat, turnover and (0). A, rotate b, move c, rocker d, vertical
149. When grinding narrow plane, use metal block as "guide" and adopt (00) grinding trajectory.
A, figure 8 B, spiral c, straight line d, circle
150.(00) connection is mainly used for positioning and connecting into locking parts in machinery, and sometimes it can also be used as overload cut-off parts of safety devices.
A, key b, pin c, sliding key d, cylindrical pin
15 1. The rightmost letter K of the internal combustion engine model indicates (00). A and B are automobiles, C is construction machinery, and D is ships and airplanes.
152. The grinding disc is mainly used for grinding (00). A, an outer cylindrical surface b, an inner cylindrical surface c, a plane d and a cylindrical hole
153. In the grinding process, the oxide film is formed rapidly, which is the (00) effect. A, physics b, chemistry c, machinery d, science
154. When the workpiece material is soft and plastic, apply (00) grinding wheel. A, coarse granularity b, fine granularity c, hard granularity d and soft granularity
155. After machining, the machine tool guide rail and sliding surface are usually machined by method (0). A, file B, scrape C, grind D and chisel
156. The contact point of fine scraping should reach (00).
A, 2 ~ 3 points /25×25 B, 12 ~ 15 points /25×25 C, 20 points /25×25 D and 25 points /25×25.
157. The higher the hardness and wear resistance of tool materials, the higher the toughness (00). A, the worse B, the better C, the same D, disappear.
158. For shaft parts with high precision, (00) should be used to check and correct.
A, steel ruler b, platform c, vernier caliper d and dial indicator
159. During rough scraping, the blade of the rough scraper was ground to (00). A, slightly curved B, straight line C, diagonal D, curved shape
160. (00) deformation will occur when the rod and shaft parts are calibrated. A, plasticity B, elasticity C, plasticity and elasticity D, torsion