PROGRAM FOR SEGMENTED HEAD LAYOUT

I wish I could remember the CAD program which advertises the ability to do sheet metal cutting layouts from developed shapes (quasi-compound shapes formed from single curvature panels). I have a simple boat design program which does this for multi-chine boat shapes. Using your orange peel analogy, as the bow curves to a point in the front, there could be, for instance, 8 panels, each orange-peel-shaped near the front end. In a boat, the bow can approximate about half of a hemisphere. Take two such boats, stand them on end, and the bows, if joined, would form a shape like a tank head.

If you're interested, I can give you a link for that software, which might work for you, but not as smoothly as you'd hope, perhaps. It's free, and was developed by a company which sells a CNC panel cutter. In fact... it's coming back to me .... here's a link.

I imagine you'd like to be able to input the basic shape (a hemisphere 30 feet in diameter, for example) and have the program draw the 3d shape as well as the panels that would approximate that shape in whatever number of panels you want. The hull design program does not so that easily: you'd have to put in coordinates of points on that hemisphere. But once you had a few shapes, you could scale up and down easily. It might be worth playing around with, anyway, to give you some ideas. Also a call to Carlson might help -- they may be aware of software that does just what you want.

I am sure there is a product that is closer to what you want, but I can't think of one. Most CAD programs, as you have probably found, can easily output a file to cut a shape (like a hemisphere) from a block of material, but few give you the flat panel shapes required to approximate that shape in 6, 10, 12, 20, or however many sides.

I'd be almost certain that the large companies making tank heads and tank head covers use software to layout the panels. You could call around and see if they will divulge their software vendor.

"Lofting" is the term used to describe getting from a shape like your tank head to the drawings for the panels. A search on that might turn up something.

Try Rhino software program.

Thanks for the ideas.

I have attached a sample of some line code from and old gwbasic program. As you will notice some of the line code is missing just after the input part of the program. If anyone has any ideas as to how to fill in the blank code it would be appreciated.

4000 CLS : PRINT

PRINT TAB(20); "DOME HEAD LAYOUT DIMENSIONS REVISED 5/25/89"

4005 PRINT : PRINT : PRINT "ENTER THE JOB NAME"; : INPUT N$

4010 PRINT "ENTER THE JOB LOCATION"; : INPUT L$

4020 PRINT : PRINT "ENTER THE HORIZ. DIA. IN FT. ID="; TAB(35); : INPUT ID

4025 PRINT "ENTER THE THICKNESS IN IN. TK="; TAB(35); : INPUT TK

4030 PRINT "ENTER THE DOME RADIUS IN FT DR="; TAB(35); : INPUT DR

4035 PRINT "ENTER THE WELD GAP IN IN. WG="; TAB(35); : INPUT WG

4040 PRINT "ENTER DEGREE INCREMENTS DESIRED I="; TAB(35); : INPUT I

4045 PRINT "ENTER THE NUMBER OF SEGMENTS NS= "; TAB(35); : INPUT NS

4075 LET R1 = ID / 2

4080 LET R2 = SQR(DR * DR - R1 * R1)

4085 LET R3 = DR - R2

4090 LET A1 = ATN(R1 / R2)

4095 LET A1A = A1 * 180 / PI

4100 LET T = A1A

4105 PRINT "DOME ANGLE= "; TAB(36); T; " DEGS"

4110 LET LDC = (DR + TK / 24) * (ATN(R1 / R2))

4115 LET TANRAD = (DR * 12 + TK / 2) * (TAN(A1))

4120 D1 = (12 * 2 * PI * R1 - (NS * WG)) / (2 * NS)

4125 Q1 = 2 * PI * TANRAD

4130 P1 = D1 / Q1 * 2 * PI

4135 VS = TANRAD - TANRAD * COS(P1)

4140 PRINT

PRINT "LENGTH DOWN FROM CENTER LDC="; TAB(36);

A = LDC: GOSUB 9000

4145 PRINT : PRINT "OUTSIDE TANGENT RAD.="; TAB(36); : A = TANRAD / 12

GOSUB 9000

4150 LPRINT TAB(15); N$; TAB(50); DATE$: LPRINT : LPRINT

4155 LPRINT TAB(25); "DOME HEAD DIMENSIONS": LPRINT : LPRINT

4160 LPRINT TAB(5); "THE HORIZ. DIA.OF THE HEAD="; TAB(40);

4165 A = ID: GOSUB 9110

4170 LPRINT TAB(5); "THE HEAD PLATE THICKNESS="; TAB(40); TK; " IN."

4175 LPRINT TAB(5); "THE DOME RADIUS OF THE HEAD="; TAB(40);

4180 A = DR: : GOSUB 9110

4185 LPRINT TAB(5); "THE WELD GAP ="; TAB(40); WG; " IN."

4190 LPRINT TAB(5); "THE INCREMENTS FOR CALCULATIONS="; TAB(40); I; "

DEG."

4195 LPRINT TAB(5); "THE DOME ANGLE OF THE HEAD="; TAB(40); T; " DEG."

4200 LPRINT TAB(5); "THE LENGTH DOWN FROM CENTER="; TAB(40);

4205 A = LDC: GOSUB 9110

4210 LPRINT TAB(5); "THE OUTSIDE TANGENT RADIUS="; TAB(40);

LPRINT TANRAD

4220 LPRINT TAB(5); "THE NUMBER OF SEGMENTS NS= "; TAB(40); NS

4225 LPRINT TAB(5); "THE OUTER VERSINE VS="; TAB(40);

LPRINT VS

CLS : LPRINT : LPRINT : LPRINT

4240 PRINT "ANGLE(DEG)"; TAB(18); "LENGTH(C2)"; TAB(32); "1/2 CHD (C1)"

4245 LET N = I

4250 REM WG= WELD GAP

4255 LPRINT "ANGLE(DEG)"; TAB(20); "LENGTH(C2)"; TAB(43); "1/2 CHD (C1)"

LPRINT

4260 LET SP = (INT(T / I)) + 1

4265 DIM L(SP): DIM C(SP)

4270 LET Z = 1

4275 FOR N = I TO T STEP I

4280 GOSUB 4320

4285 LET Z = Z + 1

4290 NEXT N

4295 LET N = T

4300 GOSUB 4320

4305 GOTO 4455

4310 STOP

4315 REM A=ANGLE IN RADIANS T0 DIM. POINT

4320 LET A = N * PI / 180

4325 REM TANGENT RADIUS

4330 LET TR = (DR * 12 + TK / 2) * TAN(A)

4335 REM R=HORIZONAL OUTSIDE RADIUS AT DIM. POINT

4340 LET R = (DR * 12 + TK / 2) * SIN(A)

4345 REM D=HORIZONZAL CIRCUMFERENCE OF ONE-HALF OF ONE

SEGMENT AT DIM. POINT

4350 LET D = ((R * 2 * PI) - (NS * WG)) / NS / 2

4352 REM HC=HORIZONTAL CHORD OF 1/2 SEGMENT

4353 HC = R * SIN(D / R)

4355 REM RA=ARC LENGTH DOWN FROM CENTER ON OUTSIDE SURFACE

TO DIM. POINT

4360 LET RA = (DR * 12 + TK / 2) * 2 * PI * N / 360

4365 REM Q=TOTAL CIRCUMFERENCE AT DIM. POINT WITH RADIUS R

4370 LET Q = TR * 2 * PI

4375 REM P=ANGLE IN RADIANS OF 1/2 CHORD OF 1 SEGMENT

4380 LET P = D / Q * 360 * PI / 180

4385 REM C1= 1/2 CHORD IN INCHES

4390 C1 = (ATN(HC / ((DR * 12 + TK / 2) ^ 2 - HC ^ 2) ^ .5)) * (DR * 12 + TK / 2)

4395 REM C2=TEMPLATE LAYOUT DISTANCE FROM CENTER TO CHORD C

4400 LET C2 = RA - (TR - TR * COS(P))

4405 LET C(Z) = C1

4410 LET L(Z) = C2

4415 PRINT N; TAB(15); C2; " IN"; TAB(32); C1; " IN"

4420 LPRINT N; TAB(15);

LPRINT C2;

LPRINT TAB(40); : LPRINT C1

4450 RETURN

The lines after the input section may not be missing -- there is no need to number lines in even increments. Subroutine 9000 is definitely missing.

With the code you have and a description of what you want, you could get a high school intern to put this together for you. My son is in his senior year and will be doing his internship this term, and this would be right up his alley -- I think his internship has to be local, however. If you have a local science and technology magnet school near you , you could probably find someone who would love to help.

Ken,

Thanks for the idea. I will look into a few of our local schools.

Tank Guy

UPDATE TO AN OLD POST REGARDING PRESSING SEGEMENTED HEADS

WE FOUND THE PROGRAM. NOW TRYING TO FIGURE SPRING BACK. SEE BELOW.

Does anyone have a formula for spring back. We are pressing .25 inch thick A-36 plates into knuckle pieces for large diameter tank heads. The blank is 6' long and pie shaped with a 5' width in back and 3' width in front. The longitude's radius is 5.5' and the horizontal varies from 15' on large end to 22' on small end. We have made a die with ribs that have the compound radius. The dies are about 6 inches wider than the blank. The dies are also 1" larger than the blanks. We intend to start by over pressing by .25 inches and continue hoping to find our way the hard way. We are wondering if there is a formula to calculate the spring back.