Designing an electrical clipper-stapler

Project Info

Case:

Our company was asked to design an electrical clipper-stapler device. This idea was first proposed many years ago, but due to technical problems did not receive much of attention and so was forgotten for a long period of time.

The new requested device was supposed to work as a dual purpose device, i.e., working as an already existing electric stapler plus an additional electric clipper. Since such a device could be of extensive use in any office, the client intended to follow a Kickstarter campaign for its prototyping and production and so requested to have the design.

Requirements:

  1. The device had to be unique and designed from scratch.
  2. The design had to have two slots, one for its stapling and the other one for its clipping function.
  3. The clipper, as well as the stapler, was to be capable of clipping 15 sheets of paper.
  4. A mechanism had to be considered for including a bunch of paper clips in a way that they could be easily charged.
  5. The final product was to be working without any falter of cling
  6. The first version was requested to be powered by the mains while the other versions were to be powered by a battery.
  7. The device was supposed to be robust and durable for at least 5 years.
  8. The aestheticism of the device was to be considered.

Solution:

Due to complexities in designing such a device that needed a careful integration of mechanical and electronic work, two teams including a team of mechanical engineers as well as a team of electronic engineers were assigned to do the work. The mechanical engineering team was responsible to offer a solution for the mechanical part including a mechanism that could provide the best solution in compliance with the given requirements while making use of the existing space within the enclosure. The solution also had to use the minimum mechanical including the gears, to increase its robustness. The electronics team had to make its design according to the mechanics for stapling and clipping.

Main features of the design

  1. Two slots were created in the front face of the device with the upper slot providing the clipping function and the lower slot providing the stapling function.
  2. In order to facilitate the charging and discharging the paper clips
  3. On the top of the device, a place for inserting the clipping cartridge was created. The cartridge was designed to be level with the top of the device and had the capacity to contain 70 paper clips.
  4. Some major components of the device were considered to be made of hard plastic. This would make the product robust and durable under any environmental condition.

Main parts of the design

  1. Power Supply: the supply was to convert the mains voltages to 5Vdc for the board
  2. MCU
  3. Clipper Sensor: composed of photodiodes and phototransistors to sense the paper
  4. Paper clips Sensor
  5. Clipper Solenoid: The duty of this part was sending a signal once a paper was inserted in the clipper slot. Upon receiving this signal, the MCU would order the clipper motor to clip the papers.
  6. Paper clips Solenoid
  7. Micro-switches

Performance of the system

The overall performance of the electronic part of the system was as below:

The system made use of a diode light at the openings of both the stapler and the clipper slot. When the light beam was cut by inserting a paper at either of the slots, the electronic circuits activated the corresponding motor and the act of clipping or stapling was initiated. The details were as follows

  1. Once the sensors sensed the diode’s light, both motors (stapler and clipper) were off meaning that there was no paper at either of the slots.
  2. When the clipper sensor did not sense the diode’s light, the clipper motor was turned on and the clipping action was done. It should be mentioned that before the clipping is done, the papers were to be tightly pressed so that all of them could be clipped. In order to resolve this issue, two bumps were added on the two sides of the clipper slot. These two bumps were attached to each other by the force of a vertical spring. Once the papers were pushed into the clipping slot, these two bumps would take them and keep them pressed. The steps taken to do the clipping was as below:
    • The motor forced the lowest clip in the cartridge to the front to take the paper
    • Before getting the paperclip reaching the rim of the papers, a small mechanical pusher was designed to push the front rim of the clip and open it, making it ready to take all the papers.
    • The clip was then further pushed to take all the papers in the slot.
    • The motor was turned off and the bunch of clipped papers was ready.
  3. When the stapler sensor did not sense the diode’s light, the stapler motor was to turn on.
Description

The final design took about 4 months before getting ready for submission to the client for the prototyping. After several design revisions, the final version was prepared in compliance with all requested requirements. It was composed of 44 mechanical pieces and components plus an electronic board. It was finally delivered to the client and met his satisfaction.

Client:
Rueben B
Date:
April 5, 2018
Location:
New York, USA
Category:
Electrical and Electronic Engineering