Sand gravel discharging middle bearing frame for annular casting machining sand spraying device

The invention discloses a specific structure of a sand gravel discharging middle bearing frame for an annular casting machining sand spraying device. In order to solve the technical problems in the prior art, the sand gravel discharging middle bearing frame is specially provided with a movable shakeout structure, when an automatic take-up device conducting tightening, a traction rope goes forwardsalong a travel track to drive auxiliary force arms to rotate around a middle bearing column, then edge sealing plates are driven to rotate, the two edge sealing plates are gradually close to each other, and an elastic rib plate is unfolded, shakeout holes are opened, so that sand gravel on the elastic rib plate conveniently falls to a fixed sieve plate through the shakeout holes, and movable shakeout is completed; and when primary shakeout is completed, the automatic take-up device is used for releasing the traction rope, the auxiliary force arms return to the starting end of the travel trackunder the action of elast