(39 of 1970)

&

The Patents Rules, 2003

COMPLETE SPECIFICATION

(See section 10 and rule 13)

1. TITLE OF THE INVENTION

“PET BOTTLE SHREDDER”

2. APPLICANT(S):

a) Name: GEETHA KRISHNAN SUBBAIYAN

b) Nationality: Indian

c) Address: G7, A-BLOCK, BRINDAVAN APARTMENTS,

CHIKOTI GARDENS, BEGUMPET- 500016, INDIA.

3. PREAMBLE TO THE DESCRIPTION

COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed. 4. DESCRIPTION

Technical Field of the Invention

The present invention relates to field of plastic bottle shredders, more particularly relates to a Polyethylene Terephthalate (PET) bottle shredding apparatus used to shred plastic bottles into predefined size.

Background of the Invention

Plastic is very familiar and well-known component that is used by everyone and, the usage now a days has increased drastically. Almost all consumers have these plastic products at their premises which can be used in multiple ways, such as, for liquid storage, toys, consumer electronics, packaging and food wrapping. After the usage, when the life of plastic is over, it is disposed into the landfills and the oceans which is not good for the environment because plastic takes many years to get decomposed.

One of the best solutions is plastic shredders which are very useful to recoup waste plastics. This recycling equipment is helpful to reduce the large plastic parts into small plastic particles and use them for plastic recycling. Shredding is an efficient waste disposal method that reduces the cost of recycling. Bottle shredders reduce the effective volume of the plastic material that can be recycled and, in this way, also reduces the cost of transportation in the recycling process.

Therefore, there are many shredders designed for shredding the plastic bottles. The prior art U.S Patent No. 4,923,126 issued on May.8 1990 to Frank. J. Lodovico, and entitled“Machine for cutting Disposable containers” discloses a machine capable of cutting plastic bottles into small pieces. It has a cutting section with a pair of parallel shafts with plurality of cutters mounted on them. It also has a feeding section which includes two shafts with each shaft having three paddles on them. The cutting unit also has two sets of combers which are supported on two pairs of spacer rods. Every cutting wheel is separated the adjacent wheel by the spacer rings between them on the same shaft. The combers are placed alternatively after each cutting wheel on one shaft. The center to center distance between the two shafts is less than the root diameter of the cutting wheel which gives an overlap on the assembly of the cutting wheels. There are two types of cut which are produced in this machine called as edge cut and the transverse cut. The edge cut produces strips of the input plastic material and the transverse cut cuts these strips to produces smaller pieces. However, the process of shredding disclosed in this invention depends completely on the feeding mechanism to crush and feed the bottle into the cutting unit. If the bottle was dropped in to the cutting unit directly without the feeding device the shredding would not take place since the bottle would not be grabbed. Moreover, the load on the motor is also high due to incorporation of more no. of mechanism involved in shredding.

The other prior art WIPO Patent No: 2008/126086A2 issued on 23 Oct, 2008 to LESHEM, Yoav and entitled“SHREDDER”. This machine consists of plurality of cutters, but unlike other machines which have two rotating shafts with the cutters mounted on them, this machine has one set of stationary cutters and one set of rotating cutters. The stationary cutters are coupled with housing and the rotary cutters are coupled with a rotating shaft. However, in this method of shredding the bottle may not get grabbed on its own without a feeding mechanism. Moreover, the invention employs an expensive manufacturing process for the cutters.

The other prior art U.S Patent No: 5,178,336 issued on Jan. 12, 1993 to Frank J. Lodovico entitled“MACHINE FOR CUTTING DISPOSABLE CONTAINERS” (shown in Fig 8). This patent mainly deals with the spacers and combers which are placed alternatively after every cutting wheel. The cutting wheels are separated by annular spacers. One set of combers partially encircle the annular combers and the other set of spacer combers partially encircle the cutters. The spacer comber and the annular combers prevent the material from getting trapped between the cutting wheels. The spacer design disclosed in this patent, would function very well to overcome the collection of the flakes on the spacer rods. However, this design would increase the overall weight of the machine as the number of spacers have been increased, thereby it increases the overall cost of the machine. Comparing to the prior art our invention is designed with a spacer/comber which reduces or excludes the probability of the shredded material to get jammed between the cutters to a great extent. Along with this our invention also overcomes the collection of the flakes on the spacer rods in a simpler way which is explained in detailed description.

The other prior art U.S Patent No: 7,284,715 B2 issued on Oct. 23, 2007 to Kris D. Dziesinski entitled“SHREDDING MACHINE”. This machine has a plastic loading section and a paper loading section. Cutting section is the same for both plastic and paper. A ram is used in the plastic loading section which pushes the material into the cutting section. The cutting section has plurality of cutters mounted on a pair of shafts. The cutters on one shaft are intermeshed with the cutters on another shaft. The machine has a collection system which may have vacuum that creates negative pressure in the system which also helps in the materials being pulled into the cutting section. However, the machine disclosed in this patent would not be able to carry out the cutting process if the ram and the negative vacuum pressure were not there. These equipments increase the overall power rating of the machine, hence consuming more energy. These additional mechanisms increase the manufacturing cost and may make it uneconomical for public stand-alone units.

Another prior art WTPO Patent No: WO 95/13139 issued on 18th May, 1995 to POWELL entitled“CONTAINER CUTTING ASSEMBLY”. This machine also consists of two shafts with plurality of cutters mounted on them. A paddle made up of planar multiple layer rubber is used to spank the material into the cutting section when the material jumps out of the cutting section when it is not grabbed by the cutters. This machine uses a motor with five horse-power rating. However, the machine disclosed under this patent would not function unless the bottle is spanked by the paddle. Otherwise the bottle would not get grabbed into the cutting unit. The arrangement of the cutters in this invention would impart heavy load on the motor due to lack of progressive cutting.

Another prior art U.S Patent No: 4,703,899 issued on Nov. 3, 1987 to Frank J. Lodovico entitled “FEEDING DEVICE FOR A CONTAINER CUTTING MACHINE”. This patent mainly deals with the feeding device for the shredding machine. The feeding device crushes the containers to enable the teeth to grip them and to draw them. However, this feeding mechanism is compulsory for the bottle to be grabbed into the cutting section without which the bottle would not be grabbed.

Another prior art U.S Patent No: 7,546,965B1 issued to John W. Parkin“DOMESTIC PLASTIC BOTTLE SHREDDER”. This machine has a hydraulic ram located above the cutting wheels which flattens the input material before it is fed into the cutting section. A waste bin is located below the shredding mechanism. The machine is designed to be as small as a garbage bin. However, the machine disclosed under this patent would not cut the plastic material if there is no prior flattening.

Now a days there are many shredding machines available in the market for shredding different materials such as paper, cardboard, plastic, etc. The basic configuration of these machines are similar i.e. they employ a cutting section which includes a pair of parallel shafts with plurality of cutters mounted on them for rotation in opposite direction. Although the basic configuration is similar, the cutter design, spacer design and some of the other aspects differ from each other which results in difference in functionality and output efficiency.

From the above prior arts, there are many shredding devices with different feeding mechanisms and sections which are used to crush, spank or push the bottle into the cutting section, without which they would not work. This feeding section takes power for rotation from the same motor in the machine which increases the overall power consumption of the machine and hence the cost. Hence there is a need to design a shredding machine which does not need a powered feeding section but grabs, crushes and shreds the bottle on its own by the cutters. Another need is that the shredding machine should be compact and user friendly which does not need an operator and can be easily placed in public places. Since, often in public places the bottles are thrown into the rubbish bins where they get dirty and contaminated which make them unsuitable for recycling.

Brief Summary of the Invention

It is therefore an object of the present invention to provide a machine for shredding plastic bottles into smaller pieces with no powered feeding section.

It is also an object of the present invention to provide a machine which is relatively easy to assemble during the production process.

A further object of the present invention is to provide a machine which is safe, compact and user friendly which can be installed in public places, shopping malls, railway stations where an operator is not needed.

In accordance with the aspect of the present invention, the PET bottle shredder comprises a cutter block, an inline helical gear box, a gear drive, a chain sprocket drive, a single-phase motor and a control unit.

In accordance with the aspect of the present invention, wherein the cutter block constitutes a plurality of components such as cutters, spacers, cutter shafts, housing and spacer rods. In accordance with the aspect of the present invention, the shredder is provided with a plurality of sensors, one is IR sensor that senses the dropped pet bottle and switches on the motor through a relay and another sensor that senses the bin full status and stops the machine with an indication.

In accordance with the aspect of the present invention, wherein a bin is incorporated beneath the apparatus that collects the shredded bottle pieces and indicates the status when it is full.

The machine includes a feeding section, which consist of a chute and inner mouth. When the plastic bottle is fed into the chute, the inner mouth guides the bottle towards the cutting unit. The cutting unit includes a pair of hexagonal shafts which have parallel central axis. The cutters which have hexagonal inner diameter which are mounted on the hexagonal shafts and hence the power is transmitted to them for the rotation. The central axes of the hexagonal shafts are parallel to each other in such a way that the distance between them is less than the root diameter of the cutters; hence it results in an overlap between the cutters which would be discussed in detail further on. Each cutter is axially placed from each other on the shaft. After every alternate cutter, spacer ring is mounted on the shaft between the cutters. The shafts are supported on deep groove ball bearings which are further fitted into the housings by interference fit. The housing also supports four spacer rods on which the spacers are hanging. The overhanging spacers are assembled on the spacer rod such that their concave cylindrical surface is facing the convex cylindrical surface of the spacer rings.

The machine starts automatically as the proximity sensor senses the bottle when it is put into the chute. The control unit is configured in such a way that the machine starts automatically when the bottle is put into the chute and stops when the bottle shredding has finished. There is also a master on/off switch at the rear of the machine with reverse rotation option. The control system also includes sensors to sense when the collection bin is full under the cutting unit. The bin is easily accessible and can be taken out of the machine.

The present invention provides an efficient shredding machine which is cost effective due to is low power consumption. The design of the cutters and their assembly which would be explained further serves in reducing the power required for the shredding process. The reduction in power required for the machine results in many advantages like low noise, low generation of heat. Other advantages like insignificant vibration is gained due to slow speed and high torque cutting operation.

From a reading of the description above of the preferred embodiments of the present invention, modifications and variations thereto may occur to those skilled in the art. Therefore, the scope of the present invention is to be limited only by the claims of this invention.

Brief Description of the Drawings

The present invention is illustrated by accompanying drawings, wherein.

Figure. 1 illustrates a perspective view depicting the whole machine including various features of the invention.

Figure. 2 illustrates a left elevation view depicting the machine including various features of the invention.

Figure. 3 illustrates a perspective view depicting the cutting unit of the machine according to the present invention.

Figure. 4 illustrates an exploded view depicting the components of a single shaft of the cutting unit according to the present invention.

Figure. 5 illustrates a cutter section depicting a stepwise explanation of the transverse cut and the edge cut taking place during the shredding operation according to the present invention.

Figure. 6 illustrates a front elevation view of the cutter design according to the present invention.

Figure. 7 illustrates a perspective view depicting the assembly of plurality of cutters showing the helical profile of the apex’s teeth according to the present invention.

Figure. 8 illustrates a perspective view depicting the assembly of the plurality of cutters with a bottle resting on the root diameter of the cutters according to the present invention.

Figure. 9 illustrates a left side elevation view depicting the cutting unit describing the way in which the jamming of the shredded particles on to the spacer rod does not take place according to the present invention. Figure 10 is a left side elevation view of a prior art showing the spanking of the bottle into the cutting unit.

Figure 11 is a perspective view depicting the cutter assembly of a prior art.

Figure 12 is a collection of different types of cutters and spacers of some prior arts.

Figure 13 is a detailed step involved in the cutting process of a prior art describing the transverse cut.

Detailed Description of the Invention

The following description is merely exemplary in nature and is not intended to limit the present invention, applications, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

The shredding machine in accordance with the preferred embodiment is shown in Fig. 1. The machine (10) is suited for shredding plastic bottles up to 2000 ml.

Referring from now on to Fig. 1, the machine (10) has body covers (11) made of sheet metal all around the mild steel cold rolled tube structure of the machine. The machine is fitted with castors (13) which make it movable. The collecting section (14) is easily accessible with a door which also has a provision to lock.

A. FEEDING SECTION

The Feeding section mainly consists of a chute (12) and an inner mouth (15) as shown in Fig. 2. The chute is designed with its position calculated in such a way that any 500ml to 2000ml PET bottle can be sensed by the (IR) infrared sensor. The opening of the chute (42) in Fig. 1 is also designed in such a way that it permits bottles only up to 2000ml. If there was no such chute (12) the smaller pet bottles like 500ml bottles would very easily miss getting sensed by the sensor and the machine would not start on its own. The inner mouth (15) ensures that the pet bottle is directed dropped towards the center of the cutting unit. When the bottle is dropped the IR sensor senses the bottle and sends signal to the control unit. The control unit in turn switches on the motor thereby starting the shredding process. The feeding section in the present invention is unique since there is no external force or push required as it is in the patents namely US Pat No. 4,923,126; 4,703,899; 4,729,515; WO 95/13139 . These patents take the power from the motor through a chain and sprocket mechanism to run the paddle shafts. This would require a motor with higher capacity.US 7,284,715 B2 has a pneumatic actuated ram in the embodiment that helps to push and force the plastic products into the cutting section. All these above- mentioned different kinds of feeding mechanism is not needed in the present invention. The grabbing, pulling and the shredding process is taken care of by the cutting unit itself which would be described in detail further on.

B. MOTOR AND GEAR BOX

The improved design of the present invention employs a motor of a very low power of 1 HP (i.e. one horsepower). The prior arts relatively use a motor with greater power since the motor also supplies its power to the feeding unit as shown in prior art Fig. 10. A significant amount of load on the motor can also be reduced with optimal design of the cutters and their assembly on the shafts which will be explained further on. The progressive cutting caused due to arrangement of the cutters on the shaft can also be seen in the prior arts. Fig. 11 shows the cutter assembly in WIPO Pat No: WO 95/13139. The motor that is used in this prior art is 5 HP (i.e. five horsepower). This is due to the lack of progressive cutting which imparts heavy load on the motor. The motor also drives the feeding paddle through chain and sprocket mechanism. Hence it requires a motor of higher power rating.

The motor placement in the present invention can be seen in Fig. 3 (The motor shown here is for representation purpose only). The motor is coupled to an inline helical gear box (17) with gear ratio 1:25.75. This gear box enables the cutting operation to be a slow speed and high torque operation. This in turn reduces the noise level and the vibration produced while the shredding is taking place. The gear box is foot mounted onto two motor fixing angles (18). The size of the F- angles are 40 mm width and 6 mm in thickness. The motor fixing angles (18) are bolted on to the housings (19).

When the torque output of the motor is multiplied by the gear box due to speed reduction, a huge amount of torque is transmitted to the machine. If an appropriate structure is not given for this transmission it may or will lead to damage of the machine. This problem is overcome by the support structure provided by the bolting of the motor fixing angles (18) and the housings (19). If the gear box and the motor had been mounted on the steel frame (20) shown in Fig. 2) of the machine, the frame would tend to bend being unable to bear the high torque. This force is borne by the housing (19) since it is strong enough having a thickness of 16 mm. The position of the gear box (17) is also calculated in a way to get the right center distance for chain and sprocket mechanism. The chain and sprocket mechanism transfer power to one of the shafts. Further the power is transmitted to the two shafts in the same speed and torque by two spur gears (22) intermeshed with each other.

C. CUTTING UNIT

As seen in Fig. 4, an exploded view of the assembly of one shaft is shown for better understanding. The hexagonal shafts can also be seen in other prior arts like EP 0736327 B l; US 8091819. In the present invention, on the hexagonal shaft (23), plurality of cutters (24) are mounted. After every cutter a spacer ring (26) is kept alternately. In order to lock the assembly of the cutters and spacer rings, lock nut (28) with its washer (27) is fastened on one side and stopper ring (29) is mounted on the other side with a circlip (not shown). The shaft on either side is supported on bearing (not shown) which is fitted in to the housing (19). The housing also supports four spacer rods (30) on which a plurality of spacers are hanging. The reason for such a position of the spacer rods would be explained in the design of the spacers.

CUTTER DESIGN

Cutter design is an important novelty of the present invention. The prior arts mentioned before do not employ such a design. The reason why most of the prior arts need a feeding mechanism is that the cutting unit is not able on its own to grab and pull the bottle into the cutting unit for the shredding process. The teeth design and the assembly of the cutters on the two shafts of the present invention exclude the necessity of a feeding mechanism or a pushing mechanism for the bottle to be grabbed into the cutting unit. The present invention grabs, pulls and shreds the bottle in one action itself. Fig. 12 shows a comparison of cutters from different prior arts in which the plastic bottle would not be grabbed by the cutting unit unless pushed in by an external force. There are two aspects in the present invention which permit the bottle to be grabbed on its own by the cutting unit. One is the cutter teeth design and the other is the cutter assembly. The cutter teeth design can be seen in Fig. 6.

Comparing with some of the prior designs shown in Fig. 12 the cutter of the present invention has five teeth. The size of the teeth is designed in such a way that it grabs the bottle by itself and does not need a feeding mechanism. The number of teeth has been decided by considering two aspects i.e. the load on the motor and the bottle grabbing capability. The fewer number of teeth, the lesser the load on the motor. However, as the number of the teeth decreases, the size of the shredded particle also increases. The size of the shredded flakes produced according to the cutter design of the present invention is 6x80mm. Even though this size is bigger than the final shredded size of the prior arts, this size is acceptable for recycling and in this way, it makes the machine also very economical. Since the size of the teeth are larger comparatively the teeth can grab the bottle on their own. The radial height of the teeth is 16 mm.

The cutter is arranged in such a way that the apex (36) of the cutters forms a helical profile. The helical profile of the apex can be seen in Fig. 7. This helical profile plays two roles. It reduces the load on the motor since all the apexes are not engaged at the same time while shredding the plastic material. The helical profile is achieved by rotating every pair of cutters 60° along the hexagonal shaft. Additionally, the cutters of one shaft and the other shaft do not engage at the same time, there is a lag of 36° between the cutters of the two shafts at the time of engaging. This means that at a point of cutting, the cutter of the first shaft and the cutter of the other shaft do not engage at the same time due to the 36° lag. This lag can be seen in step 1 of Fig 5. This also ensure that the load on the motor is less.

The assembly is made easy by having a semicircular cut out (37) as a reference point in the hexagonal inner diameter (38) of the cutter The helical profile also ensures that when the bottle is dropped, it can completely rest on the surface of the root diameter (R) of the cutters of both the shafts as shown in Fig 8. If the number of teeth would have been more, the bottle would never rest on the root diameter and always some or the other teeth would hinder it from resting on the root diameter thereby hindering it from getting grabbed. Hence the shredding would never start unless it is pushed in by an external force like the different feeding mechanism mentioned before in the prior arts.

The axial distance between both the shafts is less than the root diameter of the cutters, this results in an overlap between the cutters. The overlap of the cutters can be seen in Fig. 5. After a few experiments it is seen that the edge cut does not take place if the overlap is less than 8mm, unlike the paper shredders which have an overlap of approximately of 2mm.

The Cutters are manufactured by laser cutting process after which they are hardened, surface ground and electroplated. This ensures the cutters to have a long life. STEP BY STEP CUTTING PROCESS

This section explains the cutting process of the present invention is three steps and its comparison with the prior arts also. The shredded flakes are formed mainly because of two types of cuts. One is the edge cut which is cut at the overlap of the cutters. It results in cut pieces of the plastic which are in strip form like“Noodles”. The second is the transverse cut which is cut at the apex (36) of each cutting tooth. US Pat No: 4,923,126 explains the process of transverse cut taking place by entrapping the plastic material between the teeth as shown in the Fig. 13. In this way it overcomes the propagation of edge cut. In this method the transverse cut takes place since the material reaches the yield point of elasticity and it gets cut. Basically, this method would work very well as far as there is an external feeding paddle or device.

Referring now to Fig. 5, which explains the cutting process of the present invention stepwise. As the plastic material (35) reaches the cutters, it is grabbed by teeth (31) and (33). The material (35) rests on the root diameter of the cutters as shown by the letter (R) which gives the support for the transverse cut. The apex of the teeth (33) hooks the material (35) and does not allow it to slip upwards when the transverse cut is taking place. In STEP - 1, the first transverse cut takes place. After the transverse cut (in STEP-2) the teeth (31) pulls the material (35) down between the cutter overlap which results in the edge cut. This results in the formation of a strip. In STEP-3 as the edge cut is going to finish, teeth (31 A) comes for the next transverse cut. It is important to note here, that the strip does not experience a complete edge cut, as it is shown by letter (T). This portion which does not experience an edge cut gives additional support for the transverse cut to take place, otherwise the material (35) would simply bend away when the teeth engages for the second transverse cut. Hence due to these two mentioned reasons the transverse cut takes place without the propagation of edge cut and without any entrapping of material as it is in the prior arts.

SPACER DESIGN

The spacer design is also an important novelty of the present invention. Some of the prior designs of spacers can be seen in Fig. 12 C, D. US Pat No: 5,178,336 i,e prior art C in Fig. 12 mainly deals with the design of combers. The spacer or comber designs in this prior art C functions well and protects the cutters and spacer rods from jamming of the shredded flakes. In prior art D in Fig. 12, the flakes (which if not in strip form) that do not fall down after cutting may be taken for a second rotation by the cutters and in this way they may get collected on the spacer rods, eventually leading to a greater jam of the flakes on the spacer rods. The problem in art D is solved by masking the spacer rods by one more set of small combers in art C. The present invention effectively overcomes this problem by positioning the rods much above the height to which the flakes can reach.

Fig 9 explains how the shredded particles do not get entangled in the spacer rods of the present invention. Most of the shredded particles fall down vertically into the collection bin. However, some of the shredded particles (40) are carried by the cutters for a second rotation since they do not fall down after getting shredded. Since there is no spacer rod positioned as it is in the prior arts the shredded particles do not have any place to get jammed because the spacer rods (30) are placed far above. By the time the shredded particles reach the spacer rods (30), they fall down by gravity and hence do not lead to any jamming.

D. COLLECTING SECTION

A plastic collecting bin is provided below the cutting unit. It is denoted by (14) in Fig. 1. It is fully covered by sheet metal covers and can also be locked (41). A sensor is placed below the cutting unit to sense when the collection bin is full and gives a bin full indication.

From the description above it is clear that various changes could be done to the preferred machine without departing from the scope of the invention.