Introduction
It is important within the plastic injection production process to have a good control of the peripheral equipment that will help to have a better performance in the working parameters.
Since with this we can manage production with relatively optimal costs, making the most of material and human resources.
objective
The main objective is based on the improvement of the performance and unnecessary consumption of electrical energy of the thermoregulators (Temperature Control Unit) to provide economic benefits as a consequence of the decrease in the consumption of electrical energy.
Justification
The increase in the price of resources that we consume daily results in the implementation of this project since the need to save and use our resources to their fullest degree of functionality is the basis of our society today.
The growth of the world population and therefore a greater demand for products results in a mass growth of production, which increases the work that is done in companies and with it the consumption of resources for their work. Today there is the need to reduce the consumption of all those resources that in turn will leave economic benefits to companies.
The improvement of the functionality of the thermoregulators to take full advantage of each of these equipment and the unnecessary consumption of these equipment due to its mismanagement. The above reasons leave as a consequence the need to apply analysis studies and implementation of corrective actions to generate a better use of this equipment.
Limitations
The time and form in which the process is carried out to determine which thermoregulatory equipment is going to enter the study could be considered, for this we have to consider:
- Plan the activities, forecasts, conditions and work assumptions, state a general plan to carry out the analysis. Anticipate problems and modify the process based on the results obtained Organization in indicating the necessary work activities among the members of the group and indicate the participation of each member of the group Execution physically carry out the activities that result from the planning steps and organization Control when verifying if everything happens in accordance with the adopted plan,
Development
This analysis focuses on the investigation of thermoregulators that are located on one side of each injection machine. These have 1, 2 or 3 thermoregulators which can have different capacities. (with capacities of 2, 3, 5 and 7.5 Hp (Horse power / horsepower) which the consequence of a higher capacity is the higher consumption of Kw. / Hr which increases the cost of electrical energy for the company and therefore consequently a higher economic expense.
The analysis is mainly based on optimizing the use of electrical energy
It began by making some measurements when analyzing in the injection machine the main water distributors to the mold known as Manifolds, which are fed by 2 thermoregulators. A Gage was connected to measure Water Pressure Temperature (° F) and Gallons per minute (GPM). The results allowed to give an analysis to be able to give way to propose a solution to the problem which was in that the injection mold had a greater degree of restriction in the fixed part of the mold.
When reviewing the calculations obtained, a comparison was made, finding a notable variation in pressure and gallons per minute resulting in variation and instability in the molding process by increasing the cycle and cooling time.
A different arrangement was proposed in which the thermoregulators of the fixed part and the Mobile part of the mold were interchanged, since if the fixed part had greater restriction, the thermoregulator of the Mobile part had a greater capacity of 5Hp and that of the fixed part only 2Hp with which we would manage to break that restriction of the fixed part.
When changing the thermoregulator on the side of the mold, we found that the gallons per minute needed were maintained and the temperature and pressure of the water were constant.
Having measured the data, we proceeded to analyze the initial measurements before making the change and after making the change, showing that this was not the solution but that the solution was in the mold.
With this analysis in general terms, it is to improve the functionality of the thermoregulators in a mold as well as to lighten the consumption of electricity for the company by the thermoregulator equipment.
The main problem that was found during the analysis and learning period was that 2Hp thermoregulators could not be implemented just because they consume less electrical energy since the demand for GPM depends on the mold.
Water flow
The water that is transported within the company's network must have a treatment in which the ppm of the salts that are dissolved in it is reduced. (When it is received from the potable water network available such as the return water from the cooling tower)
In this part of the process, the water passes through the Thermoregulator which is in charge of allowing the passage of the water that comes from the cooling tower only allowing the passage if the water has the temperature already established by the thermoregulator (otherwise the mechanism does not allow the passage of water and returns it to the cooling tower) towards the injection process for cooling the plastic parts.
When the water has the established temperature and the thermoregulator allows it to pass into the process, it is distributed by pipes with the aforementioned standard which transport the water to hoses with the same standard to a distributor called Manifold, the length of this path of hoses and the changes in diameter and the length of the route in these affect the variables to which the water flow is subjected.
The Manifold is responsible for distributing the water to the different internal channels of the injection mold, which can be found distributed in different ways since there are different types of distribution of the mold cooling system.
This distribution also affects the process of cooling the water in the mold since these channels have small diameters which affect the pressure of the water and the amount of water that passes through the mold.
Some of the most common variables that occur and affect the results of these tests may be the following…
- Hose plugged or thermo plugged by scale (unusual) Bridging in hoses Hose diameters Variation in hose dimension Length of run of water pipes Insufficient thermoregulator capacity Flow restriction in mold.
The study of the water itself is quite a complicated task since it involves a series of calculations with which it is determined or can be known if the water flow is correct and guarantees a turbulent flow in the internal channels of the mold since this Turbulent flow provides greater efficiency in cooling the injected parts.
In the next stage of the analysis it is important to determine the Rn (Reynolds number) that were presented in the process water flows.
The data gave results that analytically are negative for the molding process since the Reynolds calculation formula indicates the following….
- Laminar flow: (1500 to 2000 Re) For flow values it remains stationary and behaves as if it were formed by thin sheets, which interact only as a function of the existing tangential forces. That is why this flow is called laminar flow. Transition: (2150 to 3500 Re) For values of the line, the dye loses stability, forming small undulations that vary over time, while remaining thin. This regime is called transitional. Turbulent flow: (5000 to 10,000) For values of after a small initial stretch with variable oscillations, the dye tends to diffuse throughout the flow. This regime is called turbulent, that is, characterized by a disorderly, non-stationary and three-dimensional movement.
The objective of this calculation consists in the knowledge of the real data to which the different flows of the injection process are found in order to know what the real condition is and to be able to calculate what is the ideal working condition of the water that enters the process.
If we know the amount of Reynolds number and calculate which would be the ideal we could guarantee which is the optimal condition to which the water must be found and thus calculate which is the ideal capacity at which the TCUs should be working. Here is the formula for calculating the Reynolds…
Rn = (3160 * GMP) / (*) ≥5000
Diameter of the pipe through which the fluid circulates or characteristic length of the system
Kinematic fluid viscosity
The experience in plastic injection processes and all the processes related to the molding of plastic parts, it is known that the GPM necessary in the cooling process to know that a turbulent flow will be generated. 3 and 4 GPM can guarantee a turbulent flow in the cooling channels of a mold (this will depend on the internal structure of the mold and other variables such as diameter of cooling channels, diameter of the hose in which the water is transported to the mold and water temperature and mold).
The calculations have to be carried out, it is shown that in the molds the demand for GPM in the molds necessary to guarantee a turbulent flow is between 3 and 5 GPM, which we will have to generate with the thermoregulators. Then, the ideal capacity of the thermoregulators for each injection machine will be determined by these fluid mechanics data. This determination is influenced by the number of inlets in which the water flow is distributed, which will be more understandable in the following table:
Thermoregulator
As shown in the previous diagram, the water passes through the thermoregulator which has the technical specifications taken from the technical manuals. The water enters a series of pipes which are distributed towards the manifold in which the different pipes and hoses distribute the flow to the different parts of the mold and as the number of pipes increases, both the flow and the pressure are distributed. of the water.
The diagram shows theoretical data which are based on the 100% operation of the thermoregulator, but the actual operation of the thermoregulator and the different variables that affect the flow of water through all the distribution channels have not been considered until now. that a study of the real efficiency of the thermoregulator be carried out as already mentioned so that the results are based on real data and not speculation.
Also in the diagram a speculation is made of a non-real expected data but it is not considered that in the path and path of the water there is a kinematic loss of water, which decreases the amount of GPM that reaches the mold and noting that the data does not are correct but technical data.
To calculate the real efficiency of the thermoregulators, a measurement equipment known as an ammeter is needed with which the amps will be measured for an indefinite time since it must wait until the variation of volts or amps of the equipment stabilizes.
Consequently, to carry out this work, the appropriate safety measures should be in place, both the procedure and the appropriate safety equipment such as gloves for electric current, ammeter, screwdriver, etc.
The procedure to carry out the measurement of amperes and volts is as follows:
- Turn off thermoregulator. Turn off the current flow. Turn the lid latch. Open the thermoregulator cover. Activate current flow. Connect ammeter to cable (white, black or red). Turn on ammeter. Turn on thermoregulator. Wait between 20 minutes and 1 hour for it to stabilize. the variation of amperes. Take measurement note. Connect the positive (red) and negative (black) cables to measure volts. Take note of measurements. Remove measurement equipment. Turn off thermoregulator. Deactivate current flow. Close thermoregulator cover. Activate current flow Switch on thermoregulator.
The steps previously written were carried out with the use of the appropriate safety equipment and prevent an accident when working with electric power.
Upon obtaining the data generated in the measurements, the necessary calculations were carried out. For the calculation of the Kw. / Hr.
(I) (E) (FP) (√3) / 1000
Where:
I: Amps.
E: Volts.
FP: Power Factor.
The previous formula is used since we are talking about a three-phase equipment. The first 2 data (amperes and volts) were measured manually with an ammeter and a voltmeter already mentioned, taking as reference the AVG (Average) of the 2 measurements. The power factor was determined by the type of load that runs through the thermoregulator circuits which is a resistive load.
The calculations of Kw. / Hr were recorded with this, the consumption and cost of the electric current of these peripheral equipment is obtained.
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Cell Measurements |
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| Injection machine |
Fixed Thermoregulator |
Mobile Thermoregulator |
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one |
Max |
Min |
AVG |
Max |
Min |
AVG |
|
n |
The objective of the formats is to register and achieve better control of the process parameters (Temperatures, Speeds, Pressure, etc.) in the injection machine.
Amps and volts measurement log
By already having the information in the registration forms, the costs of the thermoregulators can be calculated based on their actual consumption of KW.
With these procedures you can calculate the efficiency of the thermoregulators, practically.
