Claims:WE CLAIM:
1. A die block assembly, comprising:
die block [P]; and
die insert [I],
wherein the die block has slot [M] to removably engage the die inserts into the slot that extends along the length of the die block [P], and
wherein the die block held to the extruder head and a slot [M], configured to engage the removable die insert [I] comprising a die profile [R’] for the extrusion of rubber, and the die profile is customized for different shapes and sizes.

2. The die block assembly as claimed in claim 1, wherein with a through opening, and with lipped runner grooves on two sides of the opening on the external face, to accept the die-insert.

3. The die block assembly as claimed in claim 1, wherein the die insert is configured to have a step profile which is configured to engage with the lipped runner grooves curved outer edge of the die block.

4. The die block assembly as claimed in claim 1, wherein the die profile [E] comprises of a profile cut into the die insert [R’] which is configured to comprises of one or more shapes to extrude the rubber.
5. The die block assembly as claimed in claim 1, wherein the assembly is configured to enable strip winding of tire treads

6. The die block assembly as claimed in claim 1, wherein the die block [P] is held to the extruder head.

7. The die block assembly as claimed in claim1, wherein insert [I] with different strip profiles [R’] can be engaged based on strip shapes and sizes required.

8. The die block assembly as claimed in claim 1, wherein the profile R’ has a length of [E] about 20-80 mm, width of about 1.5 mm to 15 mm [F].

9. The die block assembly as claimed in claim 1, wherein the profile R’ has a length [E] of 67mm and width of 9 mm.

10. The die block assembly as claimed in claim 1, whereinthe profile R’ is cut or made in a die insert of length about 90 mm.

11. The die block assembly as claimed in claim 1, wherein the die insert is configured to be inserted across the face of a die-block of about 130 mm length with a through opening, and a lipped runner groove to engage the die-insert. , Description:FIELD OF INVENTION
The present invention relates to the field of rubber. More importantly it relates to quick change die inserts for small extruded rubber profiles by making changes in the die block. It relates to insertable die inserts of variable profiles for ease of rubber extrusion of various desired shapes.

BACKGROUND ART:
Frequently, it is desired to form amorphous masses of material into end products of predetermined shape and thickness, utilizing machinery which affords substantial uniformity, speed and ease. Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed through a die to obtain the desired extruded cross-section. In rubber extrusion the die is a precise and specific tool made by cutting an opening through a blank of steel. Extrusion dies can be made to form a virtually limitless array of shapes and sizes.

US Publication No. 20160176096 relates to a cross-head die assembly for use with an extruder. The cross-head die assembly includes: an inlet section having an inlet for communicating flow from the extruder to one or more flow channels formed in a support block; and an outlet, a removably mounted die located at the outlet and in fluid communication with the one or more flow channels; said support block further comprising an interior slot extending from a first side of the support block to an outlet passageway; a removable cassette positioned in the interior slot, wherein the front end of the removable cassette is positioned to seal the outlet passageway of the slot so that the slot is isolated from the flow.

Publication No. US2005147702 (A1) relates to a die insert for an extruder, which can suppress the motions of cords at a rubber topping time to improve the disturbance of the cord array pitch of a topping sheet drastically thereby to improve the homogeneity and quality of the topping sheet. In the die insert for the extruder, cord slots are provided at their exit portions with flat faces having channels leading to the cord slots at die insert leading end portion, and the channels for passing a cord array are formed open in the flat faces. The channels in the flat faces preferably have a ratio of L/D of 1 to 20 between their open length (L) and diameter (D), and the flat faces are preferably formed to have a step S between the surface side and the back side of the cord array.

Publication No. CN203994630 (U) relates to a machine head of a rubber extruder. The machine head comprises insert plates, a machine head die body, an extrusion frame plate and an extrusion plate; sizing material flow passages are arranged inside the machine head die body, and a groove is formed in the middle part of the machine head die body; the insert plates are arranged on the outer sides of the machine head die body, and are connected with the machine head die body in a sliding manner; the extrusion frame plate is arranged in the groove, and a pre-extrusion plate is arranged on the side, close to the sizing material flow passage, of the extrusion frame plate; the extrusion plate is arranged on an outer side of the extrusion frame plate; a pair of surfaces which are oppositely arranged and can lock the extrusion frame plate by moving the insertplates are arranged on the insert plates and the extrusion frame plate; a pair of surfaces which are arranged oppositely and can lock the extrusion plate by moving the insert plates are arranged on the insert plates and the extrusion plate.

US Publication No. 20130037987 relates to a profiled extrusion replication process is disclosed that includes steps of (a) extruding a molten material through an extrusion die having at least one profiled die lip to form a molten extrudate having first and second major extrudate surfaces and having a first structural feature in the first major extrudate surface; (b) bringing the molten extrudate into contact with a tool surface comprising one or more second structural features so as to cause a portion of the first structural feature in the first major extrudate surface to contact the one or more second structural features on the tool surface; and (c) cooling the molten extrudate to provide the structured film. Generally, the various embodiments of the method of the present invention include extruding an initial melt stream through a profiled extrusion die insert. In some exemplary configurations, profiled extrusion die insert has at least one profiled die lip having die lip profile features. Profiled die exit opening is non-rectilinear, meaning that exit opening as a whole is in a form other than a rectangular shape; however, portions of profile die exit opening could be rectilinear in form. Features on profiled die lip can be made by milling, machining, grinding, electron discharge machining or any other suitable method. Die insert may be removed and replaced by a die insert of a different profile, if desired. It will be understood that the profiled die exit opening may have a variety of shapes, to accommodate extrudate profiles of different configurations. The die lip is similar to the die lip discussed above, wherein dielip has a profile that is a combination of non-rectilinear portions and rectilinear portions. The profiles are generated by a set of die inserts put together, one of which has profile cut into it.

Publication No. JP2012152914 (A) relates to attachment and detachment of a strainer in a rubber extruder. The rubber extruder includes: a supply part for supplying a rubber material; a screw for transferring the rubber material supplied to the supply part to a head while kneading; a cylinder housing the screw; the head fitted to the end of the screw in the cylinder; and a die holder attached to the head freely detachably. The die holder is provided with: a nozzle for molding the rubber material supplied from the head; a nozzle holding part holding the nozzle; and an insert introducing the rubber material supplied from the head to the nozzle. The insert is provided with a recess to hold the strainer freely detachably around a passage of the rubber material supplied from the head.

US Patent No. 4,124,346 relates to a die clamp fixing an extruder final product profile die secured relative to an extruder die head vertical front face and conveniently removed or interchanged. The die clamp swings about a horizontal pin to a horizontal position where the final die can be lifted freely from or placed on the clamp. The arrangement provides for a flow distributing insert readily removed or interchanged in like manner.

US Patent No. 4,316,710 relates to a duplex extruder head for receiving extrudate from each of two extruders to deliver a composite unitary extrudate such as tire tread stock has a cavity plug or vee-block insert secured in an open top channel-shaped receiver without bolts or hinges by a pair of slidable clamps. The head also has a transverse slot for slidably receiving a die assembly endwise into the slot. The die assembly is then elevated to operating position and securely clamped by a pair of wedge-like gibs. Clamping of either the insert or the die assembly is effected by hydraulic cylinder or equivalent means. The referred patent discusses about the duplex extruder head & the slot mentioned here is to receive the whole die assembly containing a separate performer and a die which is then securely clamped by gibs which is a common technology followed in Duplex extruders. Whereas the TVS invention has a die-block with a slot into which the profile insert is placed.

US Patent No. 5,061,166 relates to an extruder head for producing profiles of rubber and/or plastic mixtures has a stationary main part which has a forward face in which the discharge ends of at least two extruders, rigid with the stationary main part open. The stationary main part has a transverse pivot shaft at one side of the forward face and, at the side opposite the pivot shaft, an abutment which projects forwardly of the forward face. A movable main part is pivoted, with play, on the pivot shaft and is swingable between a closed position in which it overlies the forward face and an open position. An extrusion die unit is disposed between the outboard end of the movable main part and the abutment. Flow channels between the movable main part and the stationary main part lead from the extruders to the extrusion die unit. Hydraulically operated clamps hold the movable main part in closed position and a hydraulic servo motor exerts on the movable main part a force parallel to the forward face of the stationary main part and directed toward the abutment. In one embodiment, there are two movable main parts pivoted at opposite sides of the stationary main part and having an extrusion die unit between them.

US Patent No. 5,221,541 relates to an extruder head made up of several segments including a first section made up of at least two plates bolted together. At least one plate is hingeably mounted to another plate in the first section to provide access to an extrudate passage defined by the plates. Downstream of the first section is a pair of mating blocks bolted to the first section further defining the extrudate passage. Inserts of hardened steel are provided and held by the plates and blocks forming the extruder head and the inserts define parts of the extrudate passage. A cooling liquid chamber is provided in at least one insert to cool the wall forming the passage. Although the passage is continuously restricted in the downstream direction, to increase the pressure of the elastomeric melt, intermittent portions of a slightly greater cross-sectional area are provided to allow expansion and thus intermittent lower pressure of the melt as it passes through the passage.

The Prior art has a single die block [P] for each and every different profile that has to be extruded at a process called strip winding of continuous rubber strips. For every profile change, extruder needs to be stopped, and die block [P] to be removed with the help of Allen keys and leftover rubber to be cleaned throughout.

In view the of above prior arts it is clear that in the available die block [P], with one die profile [R] cut in, only single strip/profile can be extruded. For each strip profile set up change, the die block needs to be changed thus consuming much time, and involving high cost of die.

Hence, the present invention aims to provide quick change die inserts for small extruded rubber profiles by making changes in the die block.

OBJECTS OF THE INVENTION:
Principal object of the present invention is to provide quick change die inserts for small extruded rubber profiles.

Another object of the present invention is to take profiles of different strip size with single die block, with only inserts changed.

Yet another object of the present invention is to add/ remove insert of different strip profiles from die block based on requirement.

Another object of the present invention is to provide insert of different strip profiles of variable shapes and sizes with the same die block.

Still another object of the present invention is to eliminate additional cost and reduce die change time.

SUMMARY OF THE INVENTION
One or more problems of the conventional prior arts may be overcome by various embodiments of the present invention.

It is the primary aspect of the present invention to provide a die block assembly, comprising:
die block; and
die insert,
wherein the die block has slot to removably engage the die inserts into the slot that extends along the length of the die block, and
wherein the die block held to the extruder head and a slot, configured to engage the removable die insert comprising a die profile for the extrusion of rubber, and the die profile is customized for different shapes and sizes.

It is another aspect of the present invention to provide a die block assembly, wherein with a through opening, and with lipped runner grooves on two sides of the opening on the external face, to accept the die-insert.

It is another aspect of the present invention to provide a die block assembly, wherein the die insert is configured to have a step profile which is configured to engage with the lipped runner grooves curved outer edge of the die block.

It is another aspect of the present invention to provide a die block assembly, wherein the die profile comprises of a profile cut into the die insert which is configured to comprise of one or more shapes to extrude the rubber.

It is another aspect of the present invention to provide a die block assembly, wherein the assembly is configured to enable strip winding of tire treads

It is another aspect of the present invention to provide a die block assembly, wherein the die block is held to the extruder head.
It is another aspect of the present invention to provide a die block assembly, wherein insert with different strip profiles can be engaged based on strip shapes and sizes required.

It is another aspect of the present invention to provide a die block assembly, wherein the profile has a length of about 20-80 mm, width of about 1.5 mm to 15 mm.

It is another aspect of the present invention to provide a die block assembly, wherein the profile has a length of 67mm and width of 9 mm.

It is another aspect of the present invention to provide a die block assembly, wherein the profile is cut or made in a die insert of length about 90 mm.

It is another aspect of the present invention to provide a die block assembly, wherein the die insert is configured to be inserted across the face of a die-block of about 130 mm length with a through opening, and a lipped runner groove to engage the die-insert.

BRIEF DESCRIPTION OF DRAWINGS
Figure 1: Top view of the die block [P] with the cut profile R of conventional die blocks.
Figure 2: Top view of the die block [P] with the die insert [I] depicting the cut profile R’of embodiments of the present invention.
Figure 3: Top view and side view of the die insert [I] and the die block [P].
Figure 4: Top view and Lateral view of the conventional die block assembly.
Figure 5: Top view and Lateral view of the die block assembly of embodiments of the present invention.
Figure 6: Top view of the die insert [I] with profile [R’].

DETAILED DESCRIPTION OF THE INVENTION:
The present invention relates to quick change die inserts [I] for small extruded rubber profiles by making changes in the die block [P]. The invention provides use of different insert [I] dimensions in a single die for tread extrusion at a different process called strip winding of rubber strips.

In present invention of extruding small rubber strips, in particular for a process called strip winding of tire treads, a single die, with different profiled inserts [I] is used within the die block itself by just replacing the required profiled inserts [I].

The die assembly of the present invention is for the purpose of strip winding of tire treads. In reference to Figure 2, 3 and 5 illustrating the die assembly of embodiments of the present invention, the die assembly comprises of a die block [P] that holds to the extruder head and a slot [M] opening at the front face end of the die with a provision where different profiled inserts [I] can be easily placed / removed without removing die block [P] itself from the extruder die head. The slot [M] works like a lock for die insert during extrusion and retains the insert in position. Wherein the die block [P] has the slot [M] as a through opening, and with lipped runner grooves [G] on two sides of the opening on the external face, to accept the die-insert. Since the block [P] is unchanged and only insert [I] changed, heat is also retained and extrusion can recommence smoothly. Also left over rubber from the die during every die set up change is greatly reduced. Die insert [I] is configured to have a L shaped groove that engages with the lipped runner grooves [G] of the die block [P]. The die insert [I] has a cut profile [R’] configured to comprise of one or more shapes to extrude the rubber. Depending on the use, different shapes and sizes ranging from trapezoid, rectangle, spherical or any other shape also can be designed. The cut profile R’ has a length of [E] about 20-80 mm and preferably about 67 mm, width of about 1.5 mm to 15 mm and preferably 9 mm [F]. wherein the profile R’ is cut or made in a die insert of length about 90 mm [D]. The die insert of the die block assembly is configured to be inserted across the face of a die-block of about 130mm length [B] with a through opening, and a lipped runner groove to engage the die-insert.

Figure 5 illustrates an exemplary embodiment.

Example 1
A die insert [I] is trapezoidal in shape. It has a cut profile R’ which has:
Base height [A] of die block [P] is 60 mm
Base width [B] of die block [P] is 130 mm
[D] as die block front face end width is 90 mm
[E] as profile [R’] width is 67 mm
[F] is profile [R’] height is 9 mm
[G] as insert slot height is 11.0 mm

The die insert [I] has a profile cut R’ of above dimensions which is inserted into the slot [M] of the extruder head.

After insert is added to die block [P], extrusion is done and profiled rubber strips are taken through a cooling drum and a conveyor to a drum where rubber strips is applied over a tyre casing. Once the process is over required Die inserts [I] are changed & same process continues. In that case only E & F dimension are changed, rest remains the same.

PROOF OF CONCEPT
Time Savings, Increased Production
In the present invention, the amount of time saved by adopting quick die change procedures plays a major role. Therefore, this comparison will examine a conventional die block setup and a die block with quick die insert arrangement.

A typical conventional setup involves:
Taking the die block [P] to the extruder using a die cart & keep it ready to fix.
Opening the extruder head assembly unit by unscrewing the clamp bolt.
Cleaning the compound in the head assembly & die block [P] area.
Removing the die block [P] from head assembly by unscrewing 5 bolts with the help of Allen keys.
Positioning the new die block [P] in the head assembly and selecting the right bolt holes for the clamping bolts.
Clamping the die block [P] to head assembly with the help of Allen keys & finally fitting mouth with the clamp bolt.
This sequence of activities usually takes 20 to 25 minutes. A well-equipped quick die insert change with skilled manpower can achieve this sequence of activity in 5 minutes.

As setup times are reduced, more productive time becomes available.

Table 1
Time taken for set-up change Conventional – Die block [P] change Innovation - Die insert [I] change
20-25 minutes 5 minutes
Cost Justification
The present invention relates to the cost benefit of replacing a new die block [P] for every profile change. Die block [P] making cost, die inventory & handling can be greatly reduced with the die insert [I] as it requires very smaller space for storage & ease for handling.

Table 2: Cost difference between conventional die block and present invention.
Cost Conventional-Die block [P] change Innovation-Die insert [I] change
Die block cost:
Rs 11000.00 Die insert cost:
Rs 4300.00

Heat retention & other benefits
The present invention relates to benefit of temperature retention in die block was as achieved by changing the profile inserts alone instead of changing the whole die block.

For smooth extrusion, the temperatures at the die block [P] have to be at certain levels. Typically, die block [P] temperature in the range of 80- 85°C is observed during profile extrusion. To resume smooth extrusion this temperature range needs to be reached. It is noted that after every die block change which is at room temperature it takes approx. 15 minutes to reach 80-85°c, whereas in the case of changing only die insert it takes only 5 minutes to reach the said temperature as die block is not removed.

Table 3
Time taken to attain 80-85°c after set-up change Conventional- Die block [P] change Innovation- Die insert [I] change
15 minutes 5 minutes

Die block [P] being a heavy piece, and being in hot condition at the time of removal is difficult to handle and may have safety issues. Use of die inserts obviates such safety issues.

Frequent removal and re-fitment of die block [P] to the main extruder body can cause wear and tear of fixing area in both parts, resulting in a much larger and costlier maintenance action to be undertaken.

Reference is drawnt to the figure 4 depicting the die block assembly of the conventional method, and figure 5 depicting the die assembly of the present invention. Figure 4 shows and Table 4 (in mm)
A- base height of die block
B-base width of die block
C- die block front face end height
D- die block front face end width
E- profile width
F-profile height
G- insert slot height

Table 4: Conventional Regular Die.
REGULAR DIE BLOCK DIMENSION IN mm
A BASE HEIGHT OF DIE BLOCK 60
B BASE WIDTH OF DIE BLOCK 130
C DIE BLOCK FRONT FACE END HEIGHT 20
D DIE BLOCK FRONT FACE END WIDTH 90
E PROFILE WIDTH 67
F PROFILE HEIGHT 9

Figure 5 illustrates the embodiment of the present invention and as an example in Table 5.

Table 5: Details of Die block assembly of the Present Invention.
PRESENT INVENTION DIE BLOCK DIMENSION IN mm
A BASE HEIGHT OF DIE BLOCK 60
B BASE WIDTH OF DIE BLOCK 130
C DIE BLOCK FRONT FACE END HEIGHT 20
D DIE BLOCK FRONT FACE END WIDTH 90
E PROFILE WIDTH 67
F PROFILE HEIGHT 9
G INSERT SLOT HEIGHT 11