The duplex pneumatic riveter in Hiscox 671 is an impact tool with nested moving parts. An inner hammer piston A and its surrounding striking cylinder C deliver alternate blows to one tool T. The cylinder strikes the tool socket H. The two moving strikers act successively on the same riveting tool.
Duplex Impact Riveter · Ideal Pressure Force and Work
An inner hammer and moving cylinder strike one tool in succession. Compare ideal pressure force and work for declared central and annular effective areas; this is not a squeeze-force or impact-peak calculation.
Equation Used
- Inner hammer and surrounding cylinder act on one tool.
- Central disk and annular pressure areas are selected modeling assumptions.
- Net pressure is constant over each entered driving travel.
- Pressure work is not delivered impact energy.
- Motion sequence is prescribed and slowed for inspection.
Use actual tool data for delivered energy, air demand and riveting capacity. This animation explains the historical arrangement.
Two strikers, one tool
The fixed outer casing carries the handle. Inside it, hammer piston A runs within striking cylinder C. A advances to the central rear face of tool T while C withdraws. On the next part of the sequence, C advances to the annular shoulder of socket H while A withdraws. The socket transfers that second blow to the same tool.
The animation distinguishes the gold hammer from the blue moving cylinder. The gray casing, socket and supported work remain fixed in this explanatory section. Orange contact lines identify the central and annular contacts in turn.
Hiscox attributes the operation to differential piston areas and describes reduced jar at the hand. The sketch does not supply a full port schedule, dimensions, masses or a quantitative vibration measurement. The animation shows the alternating contact sequence with brief inspection holds; it does not calculate the pressure switching or impact transient.
Explore the two ideal driving areas
The calculator uses a selected central disk area for A and an annular area for C. Enter the inner effective diameter, outer-to-inner diameter ratio, net driving pressure and the two driving travels. These effective areas and travels are inputs for an ideal pressure-work comparison, rather than dimensions supplied by the historical illustration.
The drawing changes diameter and travel with those inputs. Every frame retains the nested arrangement and the same tool-contact plane. Increasing a stroke increases its travel and ideal pressure work; it does not multiply pressure force.
There is no toggle multiplier or paired squeeze load. The two pressure-force values are not added to claim a simultaneous forming force.
Force and work under stated pressure assumptions
For inner diameter d and outer effective diameter D, Aₐ=πd²/4 and A꜀=π(D²−d²)/4 in mm². The ratio control sets D=d×ratio/100.
Convert pressure from psi to N/mm² using p=P×0.006894757293168. Ideal pressure forces are Fₐ=pAₐ and F꜀=pA꜀.
At constant net pressure, pressure work over each driving travel is Wₐ=Fₐsₐ/1000 and W꜀=F꜀s꜀/1000 joules when travel is in millimetres. Their sum is a work total over two successive driving travels, not a peak force or simultaneous blow.
This estimate excludes pressure variation, exhaust losses, return-stroke work, seal friction, moving masses, rebound and impact-transfer efficiency. Actual delivered blow energy and impact force cannot be obtained from pressure and bore alone.
Example: 30 mm inner diameter and 45 mm outer diameter
At 100 psi assumed net driving pressure, the central area is about 706.86 mm² and the annular area 883.57 mm². The ideal pressure forces are about 487.36 N on A and 609.20 N on C.
With 30 mm hammer travel and 15 mm cylinder travel, the corresponding pressure-work estimates are 14.62 J and 9.14 J, totaling 23.76 J over the two driving travels. These values are not measured energy delivered to a rivet.
Doubling A travel doubles its work estimate while leaving both areas and both pressure forces unchanged. Changing outer diameter changes C’s annular area, without changing A’s central area.
What this model can and cannot establish
The nested strikers alternate their contact with one tool. This illustration explains that motion; it does not determine port timing, pressure histories, impact speed or actual recoil.
The pressure-force and work estimates do not determine a suitable rivet material or diameter, forming quality or production rate.
The short contact holds make the sequence readable. Real hammer contact is brief and involves elastic and plastic deformation, which the illustrated rigid tool and work stack do not simulate.
Duplex riveter questions
Does duplex mean two rivets at once here?
No. In this source it refers to the alternating action of the hammer and its moving cylinder on one tool.
Is pressure force the impact force?
No. Pressure accelerates the moving parts. Impact force depends on velocity, mass, contact stiffness and deformation over a short contact time.
Why use an annular area for C?
It is the explicitly selected differential-area model used for this calculator. The exact effective areas of a real tool must come from its construction and pressure surfaces.
Does the animation predict recoil reduction?
No. It illustrates the source’s alternating motion, but does not solve momentum exchange or hand-transmitted vibration.
Primary references
Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, device 671, printed page 180: nested hammer A, cylinder C, socket H and tool T.
Engineering News, March 3, 1898, discussion of pneumatic riveting tools, describes a counterbalancing arrangement in which cylinder and piston strike alternately. The calculated pressure work is an ideal estimate, not a tool performance rating.
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