实用机械制造考研题库答案曝光——针对非圆柱形工件加工部分

Homework 11

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5.1 试比较铣削加工方法与车削、钻削加工方法的特点。

Milling:
Milling operation involves using multi-point rotary cutters to remove material from workpiece.
Turning:
Turning involves rotation of the workpiece while the cutting tool moves in a linear motion. This results in a cylindrical shape. A lathe is the machine of choice for all turning operations.
Drilling:
Drilling creates a round hole in a workpiece. A drill press or tapping machine is designed for drilling, but the process can also be performed using a milling machine. Chips are bit of waste metal produced when machining a workpiece.

5.2 铣削用量要素与车削用量要素有何不同？铣削层参数有什么特点?

It is clear that turning cutter just is single point tool, instead, milling cutter is multipoint tool. So that milling has one more cutting parameter, feed speed per tooth f_z.
铣削用量要素包括：铣削速度、铣削深度、铣削宽度、进给量，而其中进给量还有每齿进给量；而车削用量要素只有切削速度，进给量，切削深度。
Characteristics of parameters of milling layer:
Milling layer is used for cut-out on the board, usually the dimension layer can be utilized for that. That involves three parameters:
Chip thickness $h_D$
Chip with $b_D$
Total area of milling layer $A_D$

5.3 试比较铣刀与车刀的几何角度标注参考平面和标注角度。周铣刀与端铣刀的几何角度标注参考平面和标注角度有什么差别？

The definition of geometrical angle and reference surface of milling cutter and turning cutter are the same, but milling cutter’s cutting edge is curved and dimensioning the geometrical angle is much more difficult.
Differences of reference surface and angles between peripheral and end milling:
The base surface is perpendicular to shaft axis in peripheral milling, and it is parallel to shaft axis in end milling. Other reference surface is similar, if it is the same name of reference surface, they are perpendicular to each other.
For peripheral milling, cutters’ cutting edge is three dimensions, so that dimensioning the angle is in the contact area. For end milling, cutters are multipoint cutters, so that dimensioning the angle would be in all of these points.

5.4 周铣与端铣、顺铣与逆铣各有什么特点？如何应用？

Characteristics:
Peripheral milling, whose cutter is placed parallel to the workpiece. End milling’s cutter is placed perpendicular to the workpiece. Both of them have two types of machining methods down milling and up milling.
Direction of cutter rotation the same as work feed is down milling, whose rake angle of cutter decreases, by contrast, it is up milling, whose rake angle of cutter increases.
Application:
Peripheral milling: cut deep slots, threads and gear teeth
End milling: cut flat surfaces into the workpiece and flat-bottomed cavities
Down milling: stainless steel, heat resistant alloy steel
Up milling: carbon steel, alloy steel

5.5 铣刀有哪些主要类型？各主要有何用途？

1. Profile sharpened cutters
   The geometry of the machined surfaces is not related with the tool shape.
   Applications: slab or plain milling, side milling, slotting, slitting or parting, end milling, face milling.
2. Form relieved cutters
   The job profile becomes the replica of the tool-form
   Applications: forming, gear (teeth) milling, splining shaft, tool forming, T-slotting, thread-milling.
   1）端面铣刀；2）圆柱铣刀；3）立铣刀；4）槽铣刀；5）成形铣刀

5.6 铣床有哪些主要类型？各主要有何用途？

Horizonal milling machine

Machining small or middle size of workpiece.
Vertical milling machine
Machining small or middle size of workpiece.
Planner-type milling machine
Machining big size workpiece.
卧式升降台铣床、万能卧式升降台铣床、立式升降台铣床、龙门铣床

5.7 试述刨削加工方法的特点以及主要应用范围。插削加工方法和机床与刨削加工方法和机床有何相同与不同？

In planning and shaping, cutters can make a horizontal and relatively linear reciprocating motion on the workpiece.
Characteristics: Main sport is a relatively linear reciprocation motion without cutting in return stroke and with single point cutter. As a result of it, cutting speed is limited, efficiency is low and there are impact and shake during cutting. However, the workpiece and cutting can be thoroughly cooled without lubricant.
Application: Shaper is usually utilized in maintenance and assemble industry. With low speed and large width cutter, planner can be used to produced product with high machining precision and comparatively low surface roughness.

Slotting vs shaping and planning
Similarities: Cutters make intermittent linear motion.
Differences: Cutters is set up in different ways and the types of cutters are different between them.
Slotting is a machining process that cutter make a vertical linear reciprocating motion on the workpiece. It is considered as vertical shaping or planning essentially.
插削主要用于单件、小批生产中加工内孔中的键槽等内表面，也可加工某些外表面；刨削主要用于外表面。

5.8 刨刀与车刀有何相同和差异？

Similarities:
The definition of cutting parameters are the same. The principle of cutting are the same.
Differences:
The ways to set up their cutters are different, so as to the sizes of cutters. Usually, planning cutter is longer than turning’s, and planning cutter’s cross-section is larger than turning’s.
与外圆车刀类似，其切削部分几何角度标注和换算方法相同，但刀体横截面一般比车刀大1.25~1.5倍，两者的安装结构有所不同。

5.9 牛头刨床上刨削与龙门刨床上刨削有什么不同？指出各自的适用场合。

Differences: In shaping process, the workpiece is static, and the cutter make a motion on the workpiece. By contrast, in planning process, the workpiece make a motion on the cutter, and the cutter is static.
Applications:
Shaper is usually utilized in maintenance and assemble industry.
With low speed and large width cutter, planner can be used to produced product with high machining precision and comparatively low surface roughness.

5.10 拉削加工方法有何特点？其主要应用范围和限制？

Characteristics:
Broaching is the machining process that cutter make a low speed linear motion on the workpiece. Its efficiency is third to eighth as milling’s. IT8~IT7 can be attained.
Broaching machine is structure-simple, and easy to be utilized. The cutting speed is slow so that tool life is long. However, the structure of cutter is complex and expensive.
Applications:
Machining hole, plain, forming surface. Usually used in large production and product with specific shape and strict precision requirement.
Limits:
For machining hole, through hole must be pre-machined so that the cutter can be moved in. Moreover, it cannot be applied in machining blind hole, deep hole, step hole or other hole with block in profile.

5.11 说明拉刀各组成部分的结构特点和作用，标注拉刀切削部分的主要几何参数。

Broaching cutter consists of pull end, neck, front pilot, roughening teeth, semi-finishing teeth, finishing teeth, rear pilot and follower diameter.
Characteristics and applications:
Pull end clamps the cutter and can transfer pull force.
Neck is a connector and convenient for pull end move through broaching machine’s block wall.
Front pilot can prevent cutter form skewing.
The cutting part involves roughening teeth, semi-finishing teeth, finishing teeth, which roughening, semi-finishing and finishing machine the workpiece separately.
Rear pilot is utilized to ensure cutter would not skew and then damage the worked surface as well as cutter’s teeth after broaching.
Follower diameter is used to assist for clamping when the cutter is long and heavy.
Dimensioning the parameters of broaching can be seen in the following figure.