FAQs for Machinery and Mold Machining

Q: What is drawing?

A: Can accurately express the shape size of the object and technical requirements.

Q: What is a projection?

A: A method by which a set of rays passes through an object to a figure on a predetermined plane

Q: Types of projection methods?

A: It can be divided into central projection method and parallel projection method. The parallel projection method is also divided into forward projection and oblique projection

Q: What is a sectional view?

A: The image obtained by a set of parallel rays of light passing through the object on the projection surface

Q: What are the three basic views of an object’s projection?

A: Main view, top view, left view

Q: What is the projection rule of three basic views?

A: Main view, top view: length aligning front; main view, left view: align height; top view, left view: equal width.

Q: What are the physical properties of metals?

A: Density, melting point, thermal expansion, electrical conductivity and thermal conductivity

Q: What is a melting point?

A: The temperature at which a metal changes from a solid state to a liquid state.

Q: What is the chemical property of metals?

A: The ability of a metal material to resist corrosion by its surrounding chemical medium at room temperature or high temperature.

Q: What are the chemical properties?

A: This includes oxidation resistance and corrosion resistance.

Q: What is antioxidant?

A: The ability to resist oxidation at room temperature or high temperature.

Q: What is corrosion resistance?

A: The ability to resist corrosion by substances such as water vapor at high temperatures.

Q: What is mechanical property?

A: The ability of metal materials to resist external forces.

Q: What are the mechanical properties?

A: Including strength, hardness, plasticity, toughness, fatigue strength and so on.

Q: What is deformation?

A: Changes in the shape and size of metal materials under external forces.

Q: Types of the deformation of metal materials?

A: Can be divided into stretch, compression, bending, distortion and shear.

Q: What is the elastic limit?

A: The maximum strength a material can withstand at the elastic stage.

Q: What is yield strength?

A: The maximum stress a material can withstand under the condition of yield.

Q: What is tensile strength?

A: The maximum stress a material can withstand before breaking.

Q: What is plasticity?

A: The property of a material that tends to deform without breaking.

Q: What is material hardness?

A: The ability of a material to resist pressure from other objects into its surface.

Q: Ways to describe hardness?

A: Brinell hardness, Rockwell hardness, Vickers hardness

Q: What is the technical performance of metal materials?

A: Refers to whether the performance of metal materials is easy to be processed and shaped.

Q: What are the technological properties of metals?

A: Including casting, welding, forging press, cutting and heat treatment.

Q: What is alloy steel?

A: In order to improve some mechanical properties of steel on the basis of carbon steel, some alloy elements are added.

Q: What does alloy steel can be divided into?

A: Can be divided into alloy structural steel, alloy tool steel, special purpose steel.

Q: What is cast iron?

A: Iron alloys with a carbon content greater than 2.11% are called cast iron.

Q: What does cast iron can be divided into?

A: White cast iron, gray cast iron, ductile iron, alloy cast iron, malleable cast iron

Q: What are the simple ways to identify steel

A: Spark identification, fracture identification, color marking identification.

Q: What is the structure of the alloy?

A: Solid solution, metal compound, mechanical mixture.

Q: What is a critical point?

A: The temperature at which a metal changes its structure.

Q: What is hardening?

A: The martensite structure is obtained by heating steel to an appropriate temperature above the critical temperature and cooling it rapidly after heat preservation.

Q: What is anneal?

A: Heat the steel to a certain temperature, keep it warm for a certain time and then slowly cool to room temperature.

Q: What is hardenability?

A: The ability of steel to obtain a quenching layer at a certain temperature after quenching under certain conditions.

Q: What is tempering?

A: A method of heating steel to a certain temperature below Ac1 and cooling it to room temperature after tissue transformation for a certain period of time.

Q: What is thermal refining?

A: A heat treatment method combining quenching and high-temperature tempering.

Q: What is the purpose of carburizing?

A: The activated carbon atoms infiltrate into the surface of the steel to increase its surface carbon content.

Q: What is thermorigidity?

A: The ability of steel to maintain hardness at high temperature.

Q: What does aluminum alloy can be divided into?

A: It can be divided into deformed aluminum alloy and cast aluminum alloy

Q: What does copper alloys can be divided into?

A: Can be divided into bronze, copper, brass.

Q: What are the three types of sparks in spark identification?

A: Straight tail sparks, pointed tail sparks, fox tail sparks.

Q: What are the functions of welding rod?

A: This includes conducting current and providing the filler metal to the molten pool.

Q: What are the forces on the molten drop?

A: There are gravity, surface tension, electromagnetic compression force, spot pressure, plasma flow force, arc gas force.

Q: What defects are easy to produce when welding cast iron?

A: There are mainly white spots, cracks, stomatal refractory oxides and so on.

Q: What is weldability?

A: Refers to the adaptability of metal materials to welding. It mainly refers to the difficulty of obtaining high quality welded joints under certain welding conditions.

Q: What are the main causes of stress and deformation during welding?

A: Uneven heating and cooling

Q: What is crystallization?

A: The process of converting metal from liquid to solid in a weld pool.

Q: What kinds of steel have common special properties?

A: Stainless steel, heat resistant steel, corrosion resistant steel.

Q: What kinds of titanium alloys are there?

A: a-type, b-type, a+b-type.

Q: How many kinds of riveting are there?

A: There are mainly lap joints, angle joints, docking.

Q: What is the operation process of hot riveting?

A: Riveted fastening and finishing nail holes, rivet heating, riveting and piercing, top stitching, riveting.

Q: What is threaded connection?

A: A removable fixed connection made of threaded parts.

Q: What kinds of thread connections are commonly used?

A: Bolt connection, double head bolt connection, and screw connection

Q: How many washers are there? What does it do?

A: It can be divided into three types of gaskets for general liner, preventing looseness and special purpose gaskets. The function is to increase the support surface, cover the larger holes, prevent damage to the parts surface and cushion.

Q: What are the washers to prevent loose?

A: Spring washer, round nut check washer, single ear stop washer, double ear stop washer.

Q: What are the important features of the tangent plane?

A: Each point on the same prime line has the same tangent plane.

Q: What is an expandable surface?

A: If a solid surface can be completely flat on a flat surface without tearing or creasing, it is called an expandable surface.

Q: What is an unexpandable surface?

A: If a solid surface cannot be naturally flat on a flat surface it is called a non-expandable surface.

Q: What are the features of the expansion method?

A: According to the property of solid surface, the surface of parts is divided into many small planes, which are used to approximate the surface of solid.

Q: What is the principle of parallel line expansion?

A: Recognize the surface of the solid as consisting of many parallel plain line, take the small area formed by connecting two prime lines and their terminal lines as the plane, just draw the real size of each small plane in sequence on the plane and you get the expansion drawing.

Q: What is the principle of radiation rays unfolding?

A: The surface of the cone is radiated into a number of conterminal triangles. After figuring out the actual size of the cone and draw them in the form of emission lines on the same plane in turn, you get the expansion diagram of the surface of the cone.

Q: What are the steps to expand a triangle?

A: Draw the necessary view of the artifacts. The real length of each side of a triangle is obtained by dividing the surface of the object with a triangle. Draw the expansion diagram in triangle order.

Q: What is the neutral layer?

A: When the plate is bent, the outer material is stretched long and the inner material is compressed and shortened. Between elongation and shortening there exists a layer of fibers called the neutral layer whose length remains constant.

Q: Why do we need plate thickness treatment?

A: When the plate thickness is greater than 1.5mm and the dimensions of the parts need to be accurate, the plate thickness treatment must be carried out. Otherwise, it will result in improper size, poor quality and even waste products.

Q: What is the principle of plate thickness treatment?

A: The expansion length shall be subject to the size of the neutral layer of the component, which is obtained by calculation. The height of the curve in the expansion diagram is based on the height of the component contact area.

Q: What is the main content of plate thickness treatment?

A: Determine the neutral layer of the bending part and eliminate the interference of plate thickness.

Q: What is blanking? What are the methods?

A: Blanking is the process of separating parts or blank from raw materials. Methods include hydraulic cutting and gas cutting.

Q: What are the features of shear machining?

A: High productivity, smooth section, able to cut metal plate and various kinds of profile steels.

Q: What is the essence of cutting?

A: By applying shear force to the material with upper and lower cutting blades, the material will undergo shear deformation and finally break and separate.

Q: What are the main measures to improve the quality of shear sections?

A: Increase the strength of the cutting blade, take reasonable clearance of the cutting blade and press the material to the lower cutting edge tightly.

Q: How does the pre-shear angle affect the shear?

A: The size of the front angle not only affects the shear force and shear quality, but also affects the shear strength directly.

Q: Types and effects of post-shear angles?

A: The function is to reduce the friction between materials and cutting blade. Usually taking 1.5 ~ 3°.

Q: How does shear affect material properties?

A: It can cause material deformation and cold hardening at the edge of the material.

Q: What are the features of gas cutting?

A: The equipment is simple, low cost and high production efficiency, which can realize the cutting of various positions in space.

Q: What are the stages of the oxy-acetylene cutting process?

A: It consists of three stages: preheating of metal, burning and blowing off of oxide.

Q: What are the requirements for metal gas cutting?

A: (1) The fuel point of a metal must be lower than its melting point. (2) The melting point of the oxide produced by combustion should be lower than the melting point of the metal itself (3) Metal burns to release a lot of heat and the metal itself has a low thermal conductivity.

Q: Why can’t cast iron adopt gas cut?

A: Because the fuel point is higher than the melting point, and the SiO2 with high melting point is generated, and the oxide has high viscosity and poor mobility, it is not easy to be blown away by the high-speed air flow.

Q: What should be noticed when using oxygen bottle?

A: It must be stable and reliable when placed; 5 meters away from other fire sources; no impact; summer sun protection; no fire in winter, apply hot water thawing.

Q: Function of tempering safety device?

A: Stop the temper flow to ensure the safety of the acetylene generator.

Q: What does a decompression device do?

A: Reduce pressure and stabilize pressure.

Q: What are the preparations before gas cutting?

A: Site preparation, check cutting oxygen streamline

Q: What is the preheating flame energy rate?

A: A unit of consumption per hour of combustible gas.

Q: Types of preheating flame?

A: Neutral flame, carbonization flame, oxidation flame.

Q: What is tempering?

A: When cutting, due to the overheat of the nozzle or iron oxide slag splash, the nozzle blocked or acetylene supply is not in time, the nozzle produced a detonation and temper.

Q: What method should be adopted when tempering occurs?

A: Close the preheated oxygen and cut the oxygen valve quickly to prevent the oxygen from pouring into the acetylene tube to extinguish the tempering.

Q: What is plasma arc cutting?

A: The process of using high temperature and high speed plasma arc as heat source to melt the cut metal or non-metal partially, at the same time blowing away melted metal or non-metal with high-speed air to form a narrow incision

Q: What are the advantages of plasma arc cutting?

A: Capable of cutting stainless steel, aluminum, cast iron, and other refractory or non-metallic materials; fast cutting speed and small deformation; low cost.

Q: What is included in the prefabrication of parts?

A: This includes riveting, welding, and drilling, tapping, threading, filling, chipping, trimming, and beveling for the preparation of assembly.

Q: What is drilling?

A: Drill holes into solid materials.

Q: What kinds of drills are there?

A: There are twist drill, flat drill, center drill etc.

Q: What is the function of the drill shank?

A: Grip and transfer the torque and axial force required for drilling.

Q: What is the role of the flat tail in a taper shank drill?

A: Increase the transfer torque to avoid the drill out in the main shaft hole or drill sleeve.

Q: What role does the guide part play in the drill?

A: It keeps the drill straight during cutting. It also has the function of repairing the hole wall and is the backup part of the cutting part.

Q: What will happen when the hole is about to be drilled?

A: The axial resistance decreases suddenly when the drill has just drilled through the workpiece. Due to the sudden recovery of mechanical clearance and elastic deformation caused by the drilling machine, the bit will automatically cut in with a large amount of feed, resulting in the breaking of the bit or the reduction of drilling quality.

Q: What is the function of cutting fluid when drilling a hole?

A: Reduce friction, reduce bit resistance and cutting temperature, improve bit cutting ability and surface quality of hole wall.

Q: What is the cutting amount?

A: The general term for cutting speed and cutting depth.

Q: What is grinding?

A: The method of machining workpiece surface by grinding wheel.

Q: What is expansion?

A: The process of spreading a surface or part of a metal structure out on a plane in turn according to its actual shape or size is called expansion.

Q: Methods to draw expansion diagram?

A: Parallel line method, triangle method, radiation method

Q: What is the expansion condition of parallel line method?

A: The element lines on the surface of the component are parallel to each other and reflect the real length on the projection surface.

Q: What is included in plate thickness processing?

A: Determine the neutral layer of the bending part and eliminate the interference of plate thickness.

Q: The change of position of plate neutral layer is related to which factors?

A: It is related to bending radius and thickness of sheet metal.

Q: What are the general principles of intersecting plate thickness treatment?

A: The expansion length shall be subject to the size of the neutral layer of the component. The curve height in the expansion diagram is subject to the height at the contact point.

Q: What is the main content of lofting?

A: Plate thickness processing, expansion drawing, and make the marking sample according to the developed component expansion drawing.

Q: What kinds of shear equipment are commonly used by riveters?

A: Gantry shears, bevel shears, disk shears, punch shears, ironworker machines.

Q: Which types of plate rolls can be divided into according to the number and layout of the rollers, ?

A: It is divided into two-roll plate rolling machine, three-roll plate rolling machine and four-roll plate rolling machine.

Q: What does blanking die can be divided into according to the structure?

A: It is divided into simple die, guide column die and composite die.

Q: What are the structural characteristics of compound blanking die?

A: It has a convex and concave die which can be used as both punch and die.

Q: What is blanking force?

A: The maximum resistance of the material to mold during blanking.

Q: What stages of the deformation process of sheet separation during blanking?

A: It is divided into elastic deformation stage, plastic deformation stage and shear cracking stage.

Q: What is the minimum bending radius?

A: The minimum bending radius that can be bent without damage to the material.

Q: What are the common ways to reduce the springback of bending parts

A: Mold correction method and pressure-adding correction method.

Q: What is the purpose of using a flanging ring when stretching?

A: It is mainly to prevent the edge of the tensile parts from wrinkling.

Q: What is the function of crank-connecting rod mechanism of the crank press?

A: It can not only make the rotary motion into reciprocating linear motion but also play a role in amplifying the force.

Q: What does sheet metal worker manual forming include?

A: This includes bending, arc bending, flanging, seam closing, and correction.

Q: What’s the function of a stretch pattern?

A: Can be used for marking materials, manufacturing separation mold and manufacturing milling cutting sample.

Q: What is edge thinning? What are the formation methods?

A: The operation of extending and thinning the edge material of the deformed part in the forming process is called edge thinning. The formation methods include press thin and pull thin.

Q: What is edge pulling?

A: The edge of sheet material is processed into curved workpiece by means of edge-pulling and edge-closing.

Q: What is edge cuiling?

A: The curling of the edge of the workpiece in order to increase the rigidity and strength of the workpiece edge.

Q: What is seam closing?

A: The edge of two plates or the two sides of a plate are folded and pressed together.

Q: What are the general steps to calculate the expansion length of the bending parts?

A: The bending parts are divided into straight section and arc section. Calculate the length of each section separately, then add up the calculated length.

Q: Under what circumstances should the cutting blanking of section steel be applied?

A: Angle bending of angle steel, channel, I-beam.

Q: What stages are the whole blanking process divided into?

A: Elastic deformation stage; plastic deformation stage; shearing stage.

Q: What is blanking?

A: A stamping process in which one part of a sheet material is separated from another part along a certain closed line using a set of punching die.

Q: Types of bolt connection?

A: There are two types: connection under axial tensile load; a connection that is subjected to lateral action.

Q: What are the anti-loose measures of bolted connection?

A: Increase friction; Mechanical anti-loose.

Q: What are the ways to prevent mechanical looseness?

A: Cotter pin; Check washer; Stop washer; Wire in series.

Q: What is welding arc?

A: A strong and lasting discharge occurs in a gas medium between two electrodes.

Q: What are the components of a welding arc?

A: It consists of cathode area, anode area and arc column.

Q: What three directions does the electrode move in?

A: Moving in the direction of the molten pool; Moving in the welding direction; Make a lateral swing.

Q: Types of welding seam based on spatial position?

A: It is divided into flat welding, vertical welding, horizontal welding and overhead welding.

Q: What are the properties of intersecting lines?

A: It is both the common line on the surface of two bodies and the boundary line. It’s always closed in space.

Q: What is the intersecting line?

A: A component consisting of two or more geometries intersecting.

Q: What are the factors that affect the quality of blanking?

A: Die gap; The center line of convex and concave dies do not coincide; The working edge of the mold is blunted by wear.

Q: What are the general principles of mold design?

A: Under the precondition of ensuring the quality of stamping, the die designed should be easy to manufacture, simple to process, low cost and convenient to use.

Q: The purpose of calculating the rolling force?

A: For proper selection of rolling equipment

Q: What is free bending?

A: When the bending is over, the impact will not occur after the punch, sheet and dies are in accordance with each other.

Q: What is a correction bend?

A: After the conformation of the punch, sheet and dies, there is another impact, which can correct the bending parts.

Q: What defects are likely to occur when pressing the end enclosure?

A: Wrinkling and swelling; straight edge indentation pit; outer surface microcrack; longitudinal tearing; deviate; an ellipse; the diameter are not the same.

Q: What is an expansion joint?

A: Pipe and plate deformation is used to achieve the sealing and fastening connection.

Q: What is the purpose of calculating the blanking force

A: In order to select equipment capability and design mold reasonably.

Q: What method be used to reduce the cutting force?

A: Inclined blade; step punch; heat the punch die.

Q: What is the purpose of calculating bending forces

A: To select the bent press and design the mold.

Q: What is included in the degree of pull deformation?

A: Including degree of mold sticking; the allowable deformation of the material stretch.

Q: How to determine the number of stretching deformation of workpiece?

A: According to the maximum deformation and material elongation of the pulled workpiece.

Q: How to determine the tensile coefficient?

A: It depends on the properties of the material, the angle of the drawing, the friction coefficient and whether the tensile deformation is made in advance.

Q: What materials are not suitable for cold working correction?

A: High carbon steel, high alloy steel, cast iron and other brittle materials.

Q: What is the correct sequence of angle steel when complex deformation occurs?

A: First correct the distortion, then correct the bending, and finally correct the angle distortion.

Q: What causes the deformation of steel structure?

A: One is caused by external forces, the other by internal stress.

Q: What are the methods to eliminate welding residual stress?

A: Integral high-temperature tempering; local high-temperature tempering; temperature difference stretching method; mechanical stretching; the vibration method.

Q: What is welding overall deformation?

A: The change in shape and size of an entire structure.

Q: What is hammering expansion method?

A: The fiber structure of the metal sheet is elongated by hammering.

Q: How to determine the length of rivet rod?

A: Determined according to the total thickness of the connected parts, the diameter gap between the nail hole and the nail rod, the riveting technology etc.

Q: What is the reason that rivet head is too small after riveting?

A: Because the nail rod is short or the hole diameter is too large.

Q: What types of metal can be divided into according to the state during the welding process?

A: It is divided into three types: fusion welding, pressure welding and brazing.

Q: What is fusion welding?

A: A method of using local heating to melt a welded joint.

Q: What is clamping?

A: With the help of external forces, the positioning parts are fixed, so that they remain in the same position in the process of machining.

Q: What is the six-point positioning rule?

A: Six locating points are used to restrict the freedom of parts in space, so as to obtain the space position of parts.

Q: What is the relative parallelism?

A: Refers to the parallelism of lines or faces measured on the part to the measuring datum line or face.

Q: What is relative perpendicularity?

A: Refers to the vertical degree of lines or surfaces measured on a part relative to the measurement datum line or surface.

Q: What kinds of clamps are used in assembly?

A: Assembly tools; Mounting fixture; Assemble hanger.

Q: What are the commonly used assembly hangers?

A: Wire rope, chain, hand hoist and special hangers.

Q: Types of guidance of blanking die?

A: Guide post, guide sleeve and guide plate

Q: How many parts are the blanking die made of?

A: It consists of a working part, material positioning part, discharging part and die base.

Q: What is the role of the stretch gap?

A: Reduce friction between the material and die and control material flow in the die cavity.

Q: What does the lock seam can be divided into according to its structure?

A: Can be divided into vertical single lock seam; Vertical double lock seam; Horizontal flat lock seam and various corner lock seams.

Q: When the external force is removed, what is the reason that the bending part bounces back?

A: Because when bending by hand, the outer surface of the sheet material is compressed by the inner surface of the tensile material, so the rebound occurs.

Q: How to get cold arch and hot arch?

A: The cold arch is obtained by shrinking the edge of the sheet material into the middle of the sheet material; the hot arch is made by heating the plate to contract.

Q: How many ways to pull out the edge?

A: There are two ways, one is to use the universal tool to pull out the edge, the other is to use the model tire to pull out the edge.

Q: What is closing edge?

A: First make the sheet material wrinkle, press the wrinkles down again to prevent stretch recovery. In this way, the length of the sheet material is reduced and the thickness is increased.

Q: What is the basic principle of edge closing?

A: The forming of the workpiece with convex curved edge is mainly caused by the contraction of the material at the outer edge of the curved plane, which increases the thickness and shortens the workpiece, forcing the vertical edge to be curved.

Q: What is the purpose of correction?

A: By applying external force or local heating, the longer fibers are shortened and the shorter fibers are elongated. Finally, the layers of fibers tend to be the same to achieve the purpose of correction.

Q: What is the principle of flame correction?

A: The deformation caused by partial heating of metal is used to offset the original deformation to achieve the purpose of correction.

Q: What are the factors that influence the effect of flame correction?

A: Rigidity of workpiece; Heating position; Heat of flame; Heating area and cooling method.

Q: What are the heating methods of flame correction?

A: There are point, line and triangle heating

Q: What are the factors that determine the process allowance?

A: Influence of lofting error; Influence of error in parts processing; Influence of assembly error; Influence of welding deformation; Effects of flame correction.

Q: What kind of sample can be divided into according to its use?

A: Can be divided into a marking-off sample, forming sample, positioning sample and rod.

Q: What are the drawing methods?

A: Direct drawing and transition drawing.

Q: How to select the sampling datum?

A: With two perpendicular lines or planes, take two center lines as the baseline or take a plane and a central Line as the baseline.

Q: What is the allowable error of lofting?

A: In the process of lofting, there will be a certain size deviation in the real sample drawing due to the influence of Lofting measuring tool, tool precision and operation skills.

Q: What is included in the structure lofting?

A: Determine the combined position and connection form of each part; Make necessary changes according to the actual production and processing capacity; Calculate or measure the material length of parts and the actual shape of flat parts; Design the mold or molding bed.

Q: What are the ways to find the real length of a line segment?

A: Rotation method; Right triangle method; Change surface method; Branch line method.

Q: What is the graph rule of the right triangle method for the real length of a line segment?

A: The projection of a line segment on any projection surface is used as a right angle side of a right triangle, the length of the corresponding projection onto the vertical axis of the plane is used as the other angular edge, the hypotenuse is the real length of the line segment.

Q: What is the method of rotation for calculating real length?

A: Rotate the general position of space around a fixed axis into parallel lines, the projection of the line on the projection surface parallel to it reflects the real length.

Q: What are the ways to find the real length of a curve?

A: Changing surface method; Expansion method

Q: What is the surface-changing method?

A: In addition, a new projection surface is designed to be parallel to the curve, so that the projection of the curve on the surface reflects the real length.

Q: What is the expansion method?

A: The expansion line obtained by straightening one length in the curve view and keeping the height of the other view constant.

Q: What are the basic features of the intersection line?

A: A transversal must be a plane figure enclosed by a closed line or curve. The transversal is the common line between the transversal plane and the solid surface. It’s a collection of points on both the transversal plane and the solid surface.

Q: What are the ways to find the intersecting line?

A: Prism method; Ridge method.

Q: What are the methods for finding the 3D intersecting line of the curved surface?

A: Tessellation lines method; latitude line method.

Q: What are the features of intersecting lines?

A: The first is the common line that intersects the surface of two bodies, which is also the boundary between two bodies. Second, the intersecting lines are closed.

Q: What is the essence of finding intersecting lines?

A: Find a certain number of common points on the surfaces of the two bodies and connect them in turn

Q: What is the selection principle of calculating the intersecting line?

A: At least one projection of the intersecting line should be known by prime line method. The intersecting line should be the simplest geometric figure by using the auxiliary plane method. The spherical method is only applicable to components with intersecting rotating body and intersecting axis.

Q: Under what conditions are the intersecting line a plane curve? Is the front projection of the curve intersecting two lines?

A: The intersecting line is a plane curve when two arbitrarily rotating bodies tangent from the same sphere intersect. At this point, when the axis of the two rotating bodies is parallel to its basic projection surface, the projection of the intersecting line on this surface is the intersection of two lines

Q: What is a straight surface?

A: A surface formed from a straight line.

Q: What are the features of the cylinder?

A: All the prime lines are parallel to each other; When using the parallel plane to cut the cylinder surface, the cross-section graph is the same.

Q: What are the features of the conical surface?

A: All prime lines intersect at one point; When using the parallel plane to cut the cone surface, its section shape is similar; The cross-line across the top of the cone is a triangle.

Q: What are the stages of plastic deformation during tensile deformation?

A: Material bending; material stretching deformation; added tension.

Q: What is tensile deformation?

A: It’s a kind of forming method to make sheet materials generate plastic deformation according to an ideal curved surface under tensile state and overcome resilience.