Die Design Fundamentals. Vukota Boljanovic
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Figure 1.19 The stripper plate.
1.2.11 Fasteners
Fasteners hold the various components of the die together. Figure 1.20 shows the commonly used socket cap screw. These fasteners are available from various suppliers, and all have a threaded portion and a larger round head provided with an internal hexagon for wrenching. As you have been doing for previous illustrations, pick out the fasteners shown in the die drawing, Figure 1.2. Note that in section views, screws are shown on one side and dowels on the other.
Figure 1.20 Socket head cap screw for use as a fastener.
Let us now consider the steps taken in designing, building, and inspecting a representative die. At the same time, you will gain an insight into the operation of press shops, tool rooms, and manufacturing plants so that your understanding of tooling and manufacturing will be better than average.
1.3.1 The Product
First, we will consider the product to be manufactured. The product engineering department designs the product. In most plants, the work consists in improving the product from year to year to meet changing styles and changing requirements of customers.
After management has decided upon the final form of the new or improved product, a directive is sent to the process planning department to route the various parts through the appropriate manufacturing departments. The process or methods engineers then plan the order of manufacturing operations and decide what operations will be used. They request that the tool design department produce designs of all jigs, fixtures, cutting tools, and dies needed for efficient production of the parts.
After a product designer has prepared layouts and assembly drawings of the product to be manufactured, the engineering department prepares detail drawings of each component the shop has to produce. These drawings contain all required views, dimensions, and explanatory notes to represent all detail features of the objects.
The part which is to be machined, formed, pressed, or inspected is called by one of the following terms:
•Part
•Work
•Workpiece
Part is the preferred term, but workpiece or, simply, work are often employed as alternate names; all three terms will be used interchangeably throughout this book.
The print on which this part, work, or work-piece is represented is called a part print. In designing a die for producing a stamping, the die designer works from a part print.
1.3.2 Process Planning
Prints of detail drawings are sent to the process planning department. When stampings are required, it is the function of this department’s employees to determine how the stampings are to be made. They decide how many operations will be required and what presses will be employed to make them. This department thus assumes the responsibility of determining the sequence of manufacturing operations. The information is noted on a series of forms:
a) Route Sheet
The route sheet (Figure 1.21) is designed to suit the requirements of the individual plant and, therefore, the information route sheets contain will vary. However, the following elements are usually included:
1.The heading. This is located at the top of the sheet and contains information such as:
•Part name
•Part number
•Drawing number
•Number of parts required
•Name of product engineer
•Date
In addition, the product name and model number may be included.
2.The number of each operation required to make and inspect the part. Numbers are most frequently listed in increments of 5, such as 5, 10, 15, 20, etc., to provide numbers in sequence for additional operations which may be found necessary in manufacture or when changes are made in the design of the product.
3.The name of each operation.
4.The name and number of the machine on which the operation is to be performed.
5.Estimates of the number of parts that will be completed per hour for every operation. These estimates are altered after production rates have been measured accurately by the time study department. Route sheets are supplied to the following departments:
•Tool design department
•Production department
•Inspection department
Of course, any machine or product will contain many components, which have been standardized and which can be purchased from outside suppliers or vendors. Such items would include screws and dowels, bearings, clutches, motors, and many others. The purchasing department would be supplied with a bill of material, and purchase orders would be issued for all parts to be bought.
Figure 1.21 A typical route sheet.
Figure 1.22 A typical tool operation sheet.
b) Tool Operation Sheet
The tool operation sheet (Figure 1.22) is prepared from the route sheet and it usually lists the following:
•Number of each operation
•Name of each operation
•Machine data
•List of all standard and special tools required for the job
•Names and numbers of all special tools that are to be designed and built. These numbers are marked on tool drawings and later stamped or marked on the actual tools for identification.
Tool operations sheets are helpful in planning and developing a tooling program. Copies go to the tool designers and to the tool purchasing department. Before proceeding further, study carefully the tool operation sheet illustrated.
c) Design Order
The design order (Figure 1.23) authorizes work on an actual design. An order is prepared for each die or special tool required and the information is taken from the route sheet. In addition, the design order may give instructions regarding the type of die preferred. The following lists the information usually given on a design order:
Figure 1.23 A typical design order.
•Department name
•Tool name
•Date
•Tool number
•Part name
•Part number
•Operation
•Machine in which tool is to be used.
1.3.3 Designing the Die
Before