Coffee bean grinding system for coffee machine

1. A coffee bean grinding system for a coffee machine, comprising: a coffee bean grinding box, and a gear box, wherein the coffee bean grinding box further comprising a bottom wall and a side wall, wherein a bearing housing is disposed on the bottom wall, and the bottom of the bearing housing is provided with an opening, a bearing disposed within the bearing housing, a transmission joint connected to the bearing, a powder scraping piece, a lower grinding blade, and a spiral head, and a pressing ring disposed on an outer side of the bearing, and a wool ring disposed between the powder scraping piece and the bottom wall of the coffee bean grinding box, wherein the pressing ring is fixed to the bottom wall to secure the bearing to the bearing housing, wherein the transmission joint penetrates through the opening in the bearing housing and inserted into an inner ring of the bearing, wherein the transmission joint further comprising a first step shaft, a second step shaft, three inserting blocks extending from a step surface between the first step shaft and the second step shaft along an axial direction of the first step shaft, wherein the three inserting blocks are evenly disposed around the first step shaft, wherein an annular flange is provided on an outer peripheral surface of an end portion of the second step shaft, wherein the annular flange prevents the transmission joint from axially moving along the bearing, wherein the powder scraping piece further comprising a step hole corresponding to the first step shaft and the second step shaft, wherein a surface of the powder scraping piece is provided with an inserting groove corresponding to the inserting block, wherein an inserting block of the three inserting blocks of the transmission joint is inserted into the inserting groove causing the transmission joint and the powder scraping piece to move synchronously.

2. The coffee bean grinding system for a coffee machine of claim 1 , wherein the transmission joint is provided with a shaft hole, and an output shaft inserted into the shaft hole.

3. The coffee bean grinding system for a coffee machine of claim 2 , wherein an outer peripheral surface of the output shaft is provided with a protrusion extending along an axial direction of the output shaft.

4. The coffee bean grinding system for coffee machine of claim 1 , wherein the powder scraping piece further comprising a convex column, wherein a center hole is formed on the lower grinding blade, wherein the lower grinding piece and the transmission joint are respectively disposed on two sides of the powder scraping piece, wherein pin holes are formed on opposite surfaces of the lower grinding blade and the powder scraping piece, a connecting pin is installed in the pin holes causing the lower grinding blade to move synchronously with the powder scraping piece.

5. The coffee bean grinding system for coffee machine of claim 4 , wherein the spiral head further comprising an insert section inserted into the center hole of the lower grinding blade and a pressing section abuts against an end surface of the lower grinding blade, an engaging groove formed in the top of the convex column of the powder scraping piece, and an engaging portion corresponding to the engaging groove.

6. The coffee bean grinding system for coffee machine of claim 5 , wherein the spiral head is provided with a threaded hole, wherein the powder scraping piece is provided with a first center hole that is coaxial with the threaded hole, wherein the transmission joint is provided with a second center hole that is coaxial with the first center hole.

7. The coffee bean grinding system for coffee machine of claim 6 , wherein the spiral head is provided with a die hole that is coaxial with the threaded hole, and a blocking portion used for separating the die hole and the threaded hole, wherein the blocking portion is capable of preventing coffee beans from entering into the threaded hole and shielding exposed screws, wherein a rubber plug is disposed in the die hole.

8. The coffee bean grinding system for coffee machine of claim 7 , wherein the gear box further comprising a gear case, a lower planetary gear group disposed within the gear case, and an upper planetary gear group connected to the lower planetary gear group, a gasket respectively disposed between the gear case and the lower planetary gear group, wherein a motor is drivingly connected to the lower planetary gear group.

9. The coffee bean grinding system for coffee machine of claim 6 , the lower grinding blade disposed between the spiral head and the powder scraping piece, wherein the connecting pin is disposed between the lower grinding blade and the powder scraping piece.