冲压是塑性成形加工方法之一以板料(金属

冲压是塑性成形加工方法之一以板料(金属

Chapter 1 Introduction

1.Definition of stamping ----a plastic forming method

Raw material----sheet metal or non-metal

Tool ----die

Equipment----press

Result----separate or deform, workpiece with shape, dimension and property.

冲压是塑性成形加工方法之一。以板料（金属、非金属）为原料，利用模具在压力机上对板料施加压力使其分离或变形获得所需零件。所需零件具有一定形状、尺寸和性能。

2.Basic requirement used in sheet forming Formability, surface quality, tolerance in thickness, and economy

3.Basic processes

(1)cutting processes（分离工序）: shearing, blanking, punching, parting, lancing, shaving (2)plastic deformation processes（成形工序）: bending, deep drawing, spinning, bulging, flanging

Chapter 2 Shearing, Blanking and Punching

1. Shearing

Equipment: straight parallel cutters t↑B↓

straight inclined cutters t↓B↑

2. Blanking and punching mechanism

(1) 3 deformation stages

(2) Features of sheared edges of the sheet metal

4 parts----rollover, burnish zone, fracture, burr (reason); main affecting factors (3 aspects)

3. Blanking and punching clearance

The effect of the amount of clearance between the punch and die on the operation process

(3)features of sheared edges

(4)dimensional precision

(5)force and power

(6)die life

4. The calculating of punch and die blade size

(1) Principles of calculation: benchmarks, limit dimension

(2) Methods of calculation: separately, coordinately

(3) Steps

5.Punch force

(1) k =1.1~1.3 (why? 3 reasons: c, t and property, cutting edges)

(2) Affecting factors (4, material, c, t, shape)

(3) Method to reduce the punch force (3, heat, staggered punches, bevel-cut edges)

a)Stripping force, Knock-out force, Ejecting force

6.Material economy

a)Layout: definitions: layout, technical scrap, structural scrap

classification: type of scrap (3),

b)Scraps: definition

functions (3, compensation,

rigid sheet, protect dies)

affecting factors (4, material,

shape and dimension, t, guide and stop way)

7.Shaving

a)Definition

b)Purpose

τ⋅⋅⋅=t L k F

1.Deformation feature

(1)Deformation zone

(2)Stress and strain in deformation zone: wide plate and narrow plate

2.Neutral curvature of strain

(1)Definition

(2)Usages: blank length of bends

the minimum bending radius

(3)Feature: inward

3.The minimum bending radius

(1)Definition

(2)Affecting factors: 4, material, bending axis, edge state of plate, bending angle

4.Spring back

(1)Definition: ↓r ↑,(2)Affecting factor: 6--material, r/t, , shape, bending method,

(3)Method to reduce spring back: 4—workpiece, bending way, compensation, stretch bending

αK

∆∆,ααμ