I. Overall Equipment Description
The complete set of equipment shown in the diagram is a parallel co-extrusion production line equipped with two independent single-screw extruder units. It consists of feeding elevators, two separate single-screw extruder main units, an electric control console, a co-extrusion composite die head, and a traction conveying cooling platform. The line realizes synchronous extrusion and integrated spiral forming of two-color dough without any twin-screw equipment throughout the whole process.
II. Complete Step-by-Step Production Process
Step 1: Separate Batching, Mixing and Dough Kneading for Two Color Raw Materials
Two separate batching areas are set up to prepare Formula A (white meat-flavor material) and Formula B (color fruit & vegetable material) respectively.
- Formula A (white spiral component): 85 parts modified corn starch, 6 parts chicken meal, 7 parts food-grade glycerin, 1 part bone calcium powder, chicken flavor essence, purified water, sorbitol, food-grade preservatives.
- Formula B (colored spiral component): 85 parts modified starch, 5 parts goat milk powder, 7 parts glycerin, natural fruit & vegetable pigments, plant fiber, sorbitol, food-grade preservatives.
The two groups of raw materials are fed into horizontal mixing tanks separately. Dry powders are pre-mixed evenly, then warm water and glycerin are sprayed in with continuous stirring to knead plastic dough. The moisture content is controlled at 28%~32%. The dough is left to stand and mature for 10 minutes, then feeding elevators convey Dough A and Dough B to the hoppers of the two single-screw extruders respectively.
Step 2: Independent Heating & Gelatinization and Synchronized Feeding of Two Single-Screw Extruders
Switch on the electric control cabinet to perform sectional temperature control on the barrels of the left and right single-screw extruders separately, with the temperature stably maintained between 70℃ and 120℃. The two screws adopt independent variable frequency speed regulation to accurately match the discharge flow rates of Dough A and Dough B, ensuring uniform thickness ratio of the two-color spiral structure. Under high-pressure propulsion inside the single-screw barrel, the dough completes starch gelatinization and maturation under high temperature, forming dense, bite-resistant texture without excessive expansion.
Step 3: Integrated Forming of Two-Color Spiral Twists via Twin-Machine Co-Extrusion Composite Die Head
The discharge outlets of the two single-screw extruders connect to one dedicated two-color spiral composite die head. Two strands of dough in different colors flow into the internal swirl guide structure of the die head simultaneously, where they are automatically twisted and wound to continuously extrude integrated long two-color spiral strips without manual twisting.
Step 4: Traction Conveying + Air Cooling for Shaping
High-temperature spiral strips freshly extruded fall onto the long traction conveying rack of the equipment and move forward at a constant traction speed. An air cooling system equipped on the conveying section continuously cools the strips for 1 to 3 hours to rapidly harden the product surface, lock spiral textures, and prevent deformation and adhesion between strips.
Step 5: Servo Fixed-Length Cutting & Waste Recycling
Cooled and shaped spiral strips are sent to a rotary servo cutter for precise cutting into standard single sticks of 6cm / 10cm / 12cm. The equipment automatically sorts defective waste materials including distorted head/tail sections and delaminated two-color products, which are collected and sent back to the mixing section for re-kneading and reuse.
Step 6: Low-Temperature Constant-Temperature Drying & Curing (Improve Bite Resistance and Dental Cleaning Performance)
Cut semi-finished products are layered on racks in the drying room and dried at a constant temperature of 45℃~60℃ for 12 to 24 hours. Materials are flipped once halfway through drying to avoid unilateral cracking. After drying, the moisture content of finished products drops to ≤10%, and a frosted hard friction layer forms on the surface, which can scrape dental calculus during chewing.
Step 7: Post-Processing Flavor Coating, Quality Inspection & Vacuum Packaging
The surface of dried finished products is evenly sprayed with chicken/beef flavor coating, and a polishing machine removes burrs from edges and corners. Batch testing items include microbial detection for Salmonella, finished product hardness test, and appearance screening for mildew. Qualified products are hermetically vacuum-packed for moisture resistance, with a 12-month shelf life under normal temperature storage.
III. Brief Description of Equipment Corresponding to Each Process Section
- Left feeding elevator: Conveys mature Dough A and Dough B to the hoppers of the two single-screw extruders respectively.
- Electric control console: Independently regulates temperature, rotating speed of the two single-screw extruders and traction speed.
- Two parallel single-screw main extruders: Complete gelatinization and high-pressure pushing for one color of dough each.
- Middle long conveying cooling platform: Realizes traction and air cooling shaping of spiral strips.
- Front-end supporting cutting equipment: Cuts spiral strips into standard single chew sticks at fixed lengths.