Device and method for making concrete expansion joint inserts
An illustrative example embodiment of a method of making a concrete expansion joint insert includes moving a material including a resin having a melt temperature through a die having a flow passage that ends in an exit having a selected geometry, increasing a temperature of only a segment of the die near the exit to an elevated temperature that is at least 1.5 times the melt temperature, and increasing the temperature of a portion of the material to an increased temperature above the melt temperature through contact with the segment having the elevated temperature.
1 . A method of making a concrete expansion joint insert, the method comprising:
moving a first material including a resin having a melt temperature through a die having a flow passage, the flow passage ending in an exit having a selected geometry, wherein the die comprises a ferrous segment formed with ferrous material and a remainder of the die comprises a non-ferrous material;
increasing a temperature of only the ferrous segment of the die to an elevated temperature that is at least 1.5 times the melt temperature, wherein the ferrous segment is near the exit; and
increasing the temperature of a portion of the first material to an increased temperature above the melt temperature through contact with interior sides of the flow passage through the die that correspond with location of the ferrous segment having the elevated temperature, wherein increasing the temperature comprises using induction heating by causing electrical current to flow along at least one conductor situated adjacent the ferrous segment.
2 . The method of claim 1 , wherein
the material includes recycled rubber; and
the elevated temperature is high enough to at least partially melt at least some of the recycled rubber in the portion of the first material.
3 . The method of claim 1 , wherein the selected geometry is rectangular and
(i) the segment includes only two of four sides or
(ii) the segment includes four sides.
4 . The method of claim 1 , comprising introducing a second material into at least one side of the die.
5 . The method of claim 4 , wherein the first material establishes a first surface characteristic of a portion of the insert and the second material establishes a second surface characteristic along at least one lateral edge of the insert.
6 . The method of claim 4 , wherein the material establishes a first color of a portion of the insert and the second material establishes a second color along at least one lateral edge of the insert.
7 . The method of claim 1 , wherein the first material comprises recycled rubber and a resin having a melt flow index that is in a range from 5 to 35 g/10 min.
8 . The method of claim 1 , wherein the elevated temperature is in a range from 1.5 to 3 times the melt temperature.
9 . The method of claim 1 , comprising adding a second material including a second resin to at least some of the portion of the first material having the elevated temperature, wherein the second material has a color that is different than the first material.
10 . The method of claim 9 , comprising heating the second material to a temperature that is lower than the elevated temperature.