22-09-2014, 10:06 AM
USE OF HOEKEN’S AND PANTOGRAPH MECHANISMS FOR CARPET SCRAPPING
OPERATIONS
USE OF HOEKEN’S.pdf (Size: 178.21 KB / Downloads: 130)
ABSTRACT
For washing of carpets, scrapping is done using a wooden plank. The edge of the plank
gives pressure on the carpet to remove dirt particles and water from the carpet surface.
The plank follows a straight-line path on the carpet surface. In this paper Hoeken’s and
Pantograph mechanisms are used to obtain a straight-line path for carpet scrapping.
Hoeken’s four-bar mechanism can produce the same desired path, but the length is very
small. The Pantograph mechanism is attached to magnify the length so that the scrapping
length per stroke is same as that by the human operator. Combining these two
mechanisms a carpet scrapping machine is developed for carpet cleaning purposes. The
machine has been designed according to the force required to remove water and dirt
particles from the carpet. It is driven by an electric motor and can move in any direction
on the carpet
INTRODUCTION
India is one of the biggest exporter of carpets in the world. Carpet processing involves
several steps e.g., weaving (hand knotted), washing, drying, trimming, etc. Here the
focus is carpet washing, which is done using a wooden scrapper (Fig. 1) by a human
being. It is a laborious and hazardous step, as several chemicals like caustic soda, etc. are
used. A carpet cleaning machine by the name “Carpet Scrapping Machine” that can
perform the same job as the human washer is developed for carpet cleaning processes.
For manual washing a wooden plank is used which has an extended wooden handle as
shown in Fig. 1. Pressure is applied on the wet carpet through the edge of plank to
remove excess wool and water from the carpet surface. The edge of plank follows a
closed path containing a straight-line and a parabolic curve as shown in Fig. 2. In order
to generate the path for manual scrapping, Hoeken’s four-bar mechanism is suitable
PREVIOUS WORK
The purpose of washing of carpet is to remove water, dust particles, excess piles and
chemical from the carpet surface. It needs a massage to open the piles and to provide
shininess of the carpet. For this purpose, the first machine was developed to copy the
action of the human washer called washerman. The machine used slider crank
mechanism where the slider was the scrapper pad. The machine hit the carpet and
removed water from the carpet surface. However, the machine was drawing back some
dirty water on the already cleaned surface during the return stroke. So a modification was
desired to exactly copy the washerman’s action i.e. move the scrapper straight in the
forward stroke and in a parabolic curve in the return stroke, as shown in Fig. 2.
To copy the profile made by the edge of wooden plank the Hoeken’s mechanism
[2] is proposed. This type of profile allows to throw water and dust particles in one
direction and returns without touching the carpet like the washerman’s scrapper.
TEST RESULTS
From A.C. supply power come to the 3 hp motor, running at 1440 rpm. Motor is
connected with a reduction gearbox (ratio 1:30) through a belt drive. From the output
shaft of gearbox power comes to the crankshaft through a chain drive. The speed of the
crankshaft is fixed at 45 rpm. On both end of the crankshaft, two cranks are rotated
which cause oscillation of the rockers. While crank rotates and rocker moves, coupler
point makes the desired profile. Pantograph linkages magnify this profile and washes the
carpet. The machine frame is constructed with angles, channels and square section. There
are five wheels in the machine. Four of them are used for forward running. Two front
wheels are power driven for easy movement. One small size caster wheel is provided at
the back for tilting the machine and turning it. To guide the machine two set handles are
included.
The machine has been sent to different carpet cleaning places in India, like Bhadohi,
Mirzapur, Srinagar, Jaipur, Gwalior and Valsad for testing and to get feedback. Even
though general functionality and performance are acceptable, the handling of the
machine is difficult particularly during turning, as it has to be done manually. The steps
will be taken in the next phase of this work.
CONCLUSIONS
A mechanized scrapping is introduced using two mechanism namely, Hoeken’s and
Pantograph mechanisms. The machine is expected to ease the manual scrapping process
in less time, thus, removing the drudgery of the washerman. Alternatively washermen
will be able to clean more carpets in a day using these machines, thus, improving their
daily income.