Screw press

Contents

Introduction

1. Analysis of the current state of screw presses

Condition of modern screw presses

Description of existing presses

Technical justification of press selection

screw VPO-20A

Purpose and Tasks

2. Process Description and Device

VPO-20A screw press

Process Description

Press device

3. Engineering calculations

Press Process Calculation

Kinematic calculation of the drive

Calculation of V-belt transmission

Calculation of chain transmission

Calculation of the driving sprocket

Strength calculation

4. Installation and operation of VPO-20A screw press

5. Safety precautions

Conclusion

List of literature used

Application

Introduction

The general name "pressing" in technology refers to a number of processes that have a different essence depending on the tasks involved: changing the shape of the material when its mass and volume are constant; changing the shape and volume of the product with constant mass; changing the shape, volume and mass of the product.

The first two cases have the goal of giving the product a certain shape and compacting it for better transportability, the third for squeezing out the liquid phase.

Food products subjected to pressing are dispersed systems consisting of a solid phase (crystals, granules, torn nut cells, etc.) or of solid and liquid phases (juice, melted fat, water).

Pressing is determined by the physical and mechanical properties of the product and the process conditions. The physical and mechanical properties of the process depend on the type of product, its technological preparation (particle size, viscosity, temperature). The pressing conditions consist of the pressing mode: pressure and duration. When squeezing, the liquid phase moves along the micropores of the product, overcoming the resistance that increases with increasing pressing pressure. It has been established that an increase in pressure above certain limits can no longer affect the yield of the liquid phase. The minimum possible amount of liquid phase that is contained in the residue (press, press) after prolonged isothermal pressing of the product at constant pressure is called equilibrium.

Depending on the nature of the process, periodic and continuous processes are distinguished.

According to the principle of action of pressure mechanisms that create force during pressing, presses are divided into belt, piston, screw, gear, roller, etc.

Separation of the liquid phase (water, juice, molten fat, etc.) by pressing is used in grain washing, processing of fruit and berry raw materials, etc. In this work, we will consider a screw press, which is designed to squeeze juice from grape berries.

Condition of modern screw presses

Today, auger presses are widely used in the food industry. They are designed to squeeze juice from grape berries, squeeze pulp, are used in the beet sugar industry for pre-squeezing raw pulp, etc.

Mainly, several types of screw presses are used in industry: horizontal press, horizontal two-screw press, inclined press and vertical press.

Depending on the type of activity of the enterprise (processing of primary or secondary raw materials (pulp)), one or another type of presses is used [1].

For example, horizontal screw presses such as VND10 and VPO20A are conveniently used to produce juice from grape berries.

And the inclined screw press PSZHN68 is more suitable for squeezing pulp to 1214% of dry travel. Vertical screw presses PVZH60 are used in the beet sugar industry and are designed for preliminary squeezing of raw pulp [2].

Technical justification of the choice of a press of shnekovy VPO - 20A

Screw press VPO20A refers to medium-capacity presses and is intended for pressing out juice from grape berries.

The use of this press is due to regional features due to the difficulty in finding a raw material base.

Along with such criteria for evaluating the advantages of the press, such as the quality of the products produced on it, ease of maintenance, technical and economic indicators of its work also play an important role: specific energy costs for pressing out, press costs, metal consumption, etc.

Despite the fact that at present the needs of the industry for presses are mainly met by the production of new (modern) ones, there are still a number of previously designed presses at the enterprises. These presses, although inferior in some respects to modern models, often have a number of advantages that make it quite reasonable and even necessary to study presses of this type, because at the same time it becomes possible to use a successful unit borrowed from the old press when designing.

Purpose and Tasks

The purpose of this course work is to analyze the design of the screw press VPO20A used to squeeze juice from grape berries and its principle of operation, as well as to carry out engineering calculations: kinematic calculation of the drive, technological and strength calculation of the press, as well as installation and operation of the press.

The task of the course work is to study the screw press as fully as possible. For this purpose, engineering calculations should be carried out, as well as a graphical part of the project, including: general view of the screw, 2 units and detail.

Process Description

The process proceeds as follows. Grape berries separated from the ridges, partially destroyed in crushers, enter the press bunker. Here, the mass (mesga) is captured by the transporting screw and supplied to the pressing screw. Juice (wort) in the section of transporting screw

Partially separates from the mezgi and gathers. This juice is of the highest quality, since it contains a minimum amount of suspended particles.

At the joint of the screws, the mass is mixed, that is, it undergoes shear deformations, which ensures the formation of a good drainage system of channels in the mezga for wort removal. [1]