Bài giảng Nhập môn điểu khiển quá trình công nghiệp

Chapter 16

Công nghệ uốn tấm

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Sheet-Metal Parts

(a)

(b)

Figure 16.1 Examples of sheet-metal parts. (a) Die-formed and cut stamped parts.

(b) Parts produced by spinning. Source: (a) Courtesy of Aphase II, Inc. (b)

Courtesy of Hialeah Metal Spinning, Inc.

Uốn là làm thay đổi hình dạng từ tấm phẳng ra hình dạng chi

tiết theo yêu cầu.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Characteristics of Sheet-Metal Forming Processes

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Cắt bằng chày và cối

Punch force, F  0.7TL UTS

 

Figure 16.2 (a) Schematic illustration of

shearing with a punch and die, indicating

some of the process variables.

Characteristic features of (b) a punched

hole and (c) the slug. (Note: The scales

of the two figures are different.)

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Shearing

Figure 16.3 (a) Effect of the clearance, c, between punch and die on the deformation zone

in shearing. As the clearance increases, the material tends to be pulled into the die rather

than be sheared. In practice, clearances usually range between 2 and 10% of the thickness

of the sheet. (b) Microhardness (HV) contours for a 6.4-mm (0.25-in.) thick AISI 1020 hot-

rolled steel in the sheared region. Source: After H.P Weaver and K.J. Weinmann.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Die-Cutting Operations

Figure 16.4 (a) Punching (piercing) and blanking.

(b) Examples of various die-cutting operations on

sheet metal.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Conventional Versus Fine-Blanking

Cấu trúc của khuôn cắt

Figure 16.5 (a) Comparison of sheared edges produced by conventional (left) and

by fine-blanking (right) techniques. (b) Schematic illustration of one setup for fine

blanking. Source: Courtesy of Feintool U.S. Operations.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Cắt xả băng bằng dao quay.

Figure 16.6 Slitting with rotary knives. This process is similar to opening cans.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Tailor-Welded Blanks

Figure 16.7 Production of an outer side panel of a car body by laser butt-

welding and stamping. Source: After M. Geiger and T. Nakagawa.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Examples of Automotive Components

Produced from Tailor-Welded Blanks

Figure 16.8 Examples of laser butt-welded and stamped automotive-body components.

Source: After M. Geiger and T. Nakagawa.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

The Shaving Process

cắt phẳng

Figure 16.9 Schematic illustrations of the shaving process. (a) Shaving a sheared

edge. (b) Shearing and shaving combined in one stroke.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Khuôn liên

hợp

Figure 16.11 Schematic illustrations: (a) before and (b) after blanking a common washer in a

compound die. Note the separate movements of the die (for blanking) and the punch (for

punching the hole in the washer). (c) Schematic illustration of making a washer in a

progressive die. (d) Forming of the top piece of an aerosol spray can in a progressive die.

Note that the part is attached to the strip until the last operation is completed.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Bending Terminology

uốn tấm

Figure 16.16 Bending terminology. Note that the bend

radius is measured to the inner surface of the bent part.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Effect of Elongated Inclusions

Figure 16.17 (a) and (b) The effect of elongated inclusions stringers) on

cracking as a function of the direction of bending with respect to the original

rolling direction of the sheet. (c) Cracks on the outer surface of an aluminum

strip bent to an angle of 90 degrees. Note also the narrowing of the top surface

in the bend area (due to Poisson effect).

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Minimum Bend Radius

Figure 16.18 Relationship between R/T ratio and tensile reduction of area for sheet metals.

Note that sheet metal with 50% tensile reduction of area can be bent over itself in a process

like the folding of a piece of paper without cracking. Source: After J. Datsko and C. T.

Yang.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Springback in Bending

Sự đàn hồi khi uốn

3

   

RY RY

R

i

 4

 3

1

   

   

ET ET

R_f

Figure 16.19 Springback in bending. The part tends to recover elastically after bending,

and its bend radius becomes larger. Under certain conditions, it is possible for the final

bend angle to be smaller than the original angle (negative springback).

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Methods of Reducing or Eliminating Springback

phương pháp để giảm sự đàn hồi

Figure 16.20 Methods of reducing or eliminating springback in bending

operations. Source: After V. Cupka, T. Nakagawa, and H. Tyamoto.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Common Die-Bending Operations

Bending Force

kYLT²

W

P 

where

k = 0.3 for wiping die,

k = 0.7 for a U-die,

k

=

1

.3 for a

V

-

d

ie

Figure 16.21 Common die-bending operations

showing the die-opening dimension, W, used in

calculating bending forces.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Bending Operations

uốn tròn

Figure 16.22 Examples of various bending operations.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Press Brake

Dập tấm

Figure 16.23 (a) through (e) Schematic illustrations of various bending operations in a

press brake. (f) Schematic illustration of a press brake. Source: Courtesy of Verson

Allsteel Company.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.

Bài giảng Nhập môn điểu khiển quá trình công nghiệp - Chương 16: Công nghệ uốn tấm