Method for sealing plastic containers for storing and processing blood

FIELD: medical engineering.

SUBSTANCE: method involves continuously measuring electric current amplitude flowing via piezo-ceramic elements of ultrasonic oscillatory system when using mechanical manual tube cross-clamping mechanisms during ultrasonic action applied to suture formation zone. Current amplitude changes are controlled in welding. The condition of current amplitude changes under measurement becoming equal to zero being satisfied, ultrasonic action is to be switched off providing in this way optimum suture quality.

EFFECT: high reliability in sealing various blood containers types.

2 dwg

 

The invention relates to the field of medical technologies associated with the collection, storage and processing of blood, and in particular to methods of sealing plastic containers for collection, storage and processing of blood, and can be used to create a modern material-technical base stations and branches of blood transfusion.

The widespread use of blood products leads to special requirements and features of their collection and storage. The exception to the technology of harvesting and processing the blood of glass containers and the widespread use of plastic containers (gamecontainer) demanded upgrading all the material-technical base stations and branches of blood transfusion.

One of the main problems of logistics technologies of collection, processing and storage of blood products is the problem of reliable sealing of plastic containers.

Currently, widespread hardware automated methods of sealing plastic containers for storage and processing of blood, based on the ultrasonic method of low-temperature seal the inlet of polymer pipes in the immediate vicinity (at a distance of not more than 10 mm) from their entry gamecontainer[1, 2, 3].

The closest in technical essence to p is antigenome technical solution is the method of sealing plastic containers [4, adopted for the prototype], namely, that sets the plot polymer tube is in close proximity to its input in the container between two flat surfaces, one of which is acoustically connected to a source of ultrasonic vibrations, carry out the compression of the tube by means of an electromagnetic actuator to touch the opposite inner surfaces of the tube between them. Then include a generator of electrical oscillations of ultrasonic frequency transform using oscillatory system electrical oscillations into ultrasonic frequency of 44 KHz and bring them into the wall of the tube within a predetermined time interval, performing ultrasonic treatment to the material transfer tube in a viscoplastic state in the zone of formation of a seam. After transfer of the material of the tube in a viscoplastic state disable a generator of electrical oscillations, while continuing to hold the tube in the form of cross-clamping condition to stabilize the sealing seam. After stabilization of a sealing seam free polymer tube and simultaneously share the sealed container and unused system pipes.

Installation modes of ultrasonic influence in the known method of sealing plastic containers is carried out manually, by changing the source is local or temporal parameters of ultrasonic treatment. The need to manually change the two independent parameters (power generator of electrical oscillations, the supply of the piezoelectric oscillatory system welder and time of ultrasonic treatment, necessary and sufficient for the formation of high-quality sealing seam), especially when using different diameter and made of various materials tubes, leads to the low quality of sealing, the possibility of thermal decomposition of the formed seam.

Thus, for each type used in the practice of gamecontainer, there is a method of ultrasonic sealing requires manual adjustment of the time interval necessary and sufficient for translation of the material of the tube in a viscoplastic state.

Due to the large variation in polymer tubes, even within the same type of gamecontainer, lack of automatic methods for determining these parameters in the sealing process automation method of sealing virtually impossible, and manual control of the process (by selecting and manually adjusting the time of ultrasonic treatment) often leads to errors. It does not provide reliable sealing and loss of a large number of valuable blood products. These shortcomings lead to the need with the Denmark of the method of ultrasonic welding, able to automatically optimize the parameters of power and time of exposure to produce a quality seal, i.e. to determine the moment of transition of the base materials in the plastic state.

Known methods of determining the moment of transfer of thermoplastic materials in a viscoplastic state [5], based on the control current flowing through the oscillating system, which allow to automate the process of ultrasonic sealing in a stationary ultrasonic welder.

However, the problem of automating the process of ultrasonic welding is not solved with the application of the known method, even with the use of well-known way of determining the moment of transfer material in a plastic state, in the devices manual for sealing containers (manual welders), in which the compression and subsequent retention of the polymer tube is muscular strength of the hand of the operator. In this case, the destabilizing factors, due to the variety of containers, added factors due to differences in muscular strength and differences in the subjective feeling of the operator is ready to welding and completion of the welding process.

The main problem with the implementation of the known method consists in the impossibility of determining m is the moment of transition of a material in a plastic state and is switched off ultrasonic treatment, i.e. long enough for mutual penetration of the material of the opposite walls of the tube at each other, after the transition material in the plastic state.

To identify the reasons for the disadvantages of this method, consider the formation of a sealing seam using muscle power operator, illustrated in figure 1. Figure 1 presents curves illustrating the change of the amplitude of the current flowing through the piezoelectric vibrating system at various efforts compression welded tube in the process of forming a sealing seam.

The values of the currents I1, I2, I3correspond to the initial current welding, and the values of I11, I21, I31correspond to the moment of transition of the material of the tube in a plastic state under different compressive efforts, equal to P1P2, R3respectively. With the constant force of the compression tube, in the process of welding (for example, curve 1), the amplitude of the current varies from its maximum value of I1to the minimum of I11. This behavior of the current amplitude caused by a softening of the material to be welded tube, the increase in acoustic contact of the tube with the working end of the oscillating system, the spreading of the molten material of the tube generally flat surface of razocherovaniya, which leads, ultimately, to reduce the q-factor of the ultrasonic vibrating system and decrease the current flowing through its piezoelectric elements, to the value of I11. Change the amount of compression, welded tubes, ranging from P1up to R3and P1>P2>R3causes the changing nature of the curve of change of current (see figure 1, curves 1, 2, 3). With the decrease in the compressive efforts, the transition tube in a plastic state (point a, b, C) occurs over a longer time interval (time t1, t2, t3).

Changing the current amplitude in the sealing process, in the case of a manual lever mechanism, due not only to the material transfer tube in a viscoplastic state, but also by changing (decreasing) the value of the compressive forces in the translation process material in a plastic state. Practical study of the correlation between the time needed for translation of material in plastic condition, and a corresponding point on the curve of change of current in the welding process showed that the points a, b, C do not correspond to the moment of mutual penetration of the material of opposite walls in each other after the transition material in the welding zone in a viscoplastic state.

In connection with the foregoing, the persons sealing of plastic containers adopted for the prototype, are unsuitable for use in manual welders working in automatic mode for the following reasons:

1. The method provides high-quality sealing only with constant force compression of welded materials, applicable during the entire welding process. When implementing a manual means of sealing this effort, due to the muscular force of the operator is constantly changing.

2. The known method allows you to record the time of the transfer material in plastic condition, but does not allow to determine the optimal time sufficient for diffusion of mutual penetration of the base materials to each other. While the shutdown of ultrasonic influence in the time of the transfer material in plastic condition, recommended by known methods, is premature, does not ensure a quality seal.

3. The current flowing through the oscillating system is determined by many factors, not only because of the influence of the welded tube (transfer of materials in a viscoplastic state), but also has its own electrical capacitance of the piezoelectric elements and the change of the capacitance changes of the ambient temperature and the oscillatory system, the heating during long-term operation up to 100-abs Celsius. In addition, this current depends on the efforts of the compression degree of damping of the oscillating system, based not only on the type of gamecontainer, but also from the muscular effort of the operator.

Thus, the method of ultrasonic sealing of plastic containers adopted for the prototype, taking into account the well-known way of determining the moment of transfer of thermoplastic materials in a viscoplastic state does not provide a reliable sealing of plastic containers of all types used when using the manual welder.

In the proposed method solves the problem of eliminating the shortcomings of the existing method of an ultrasonic sealing of plastic containers for storage and processing of blood and a method that provides a reliable sealing of all types of containers when using the muscular effort of the operator to compress the polymeric tube in manual ultrasonic welder.

The technical result of the invention is expressed in increasing the reliability of the sealing of all types of geocontainers by eliminating the need to identify and rebuild time of ultrasonic influence.

The essence of the proposed solution lies in the fact that in the known method sets the plot polymer tube is in close proximity to its input in the containers is R, between two flat surfaces, one of which is acoustically connected to a source of ultrasonic vibrations, and the second with the clamp strap, carry out the compression of the tube until it touches the opposite inner surfaces of the tube between them. Ultrasonic treatment is carried out for a set time, turn off the ultrasonic impact and hold the tube in a compressed state until the stabilization of the sealing seam. The compression tube in the proposed method is carried out on muscle strength of the operator by moving the handle, connected via lever-rocker mechanism with anti-squeak plate. The presser bar is moved towards the source of ultrasonic vibrations to the education gap, the magnitude of which is set equal to the wall thickness of the tube resealable container and ultrasonic influence to include the compression tube. In the process of ultrasonic treatment on the tube continuously measure the current amplitude, which is the difference between the current flowing through the piezo vibrating system and reactive capacitive component of this current, due to its own electrical capacitance of the piezoceramic elements record the amplitude of this current at the point of activation of ultrasonic influence and compare its value with the amplitude t of the spacecraft at the moment of its minimum value during the welding process, provide compression of the tube decreasing the amplitude of this current is not less than twice, then continue welding and off the ultrasonic treatment is carried out in a time when the rate of change of the amplitude of the measured current becomes zero.

The essence of the proposed solution is illustrated figure 2, which shows the change of amplitude of a current of a mechanical branch, which is the difference between the current flowing through the piezo vibrating system and reactive capacitive component of this current, due to its own electrical capacitance of the piezoceramic elements in the process of its seal when clamped weld zone manual pinch mechanism.

At the initial moment the magnitude of the welding current is equal to I1. It is determined by the maximum power of the initial compression of the tube and minimum acoustic contact of the compressed tube and a flat surface that is associated with the ultrasonic vibrating system. Acoustic contact is minimal, as is pressed against the flat surface of the tube at first not fully hugs her.

In the process of absorption of acoustic energy, softening the tube and its crushing most of the working surface (increase in the area of acoustic contact) increases the degree of damping of the oscillating system and, as a consequence the vié, decreases the current flowing through it, reaching its minimum value (point b). Point In the match the moment of the maximum damping of the oscillating system.

Plot SU corresponds to the transition of the material of the tube in a viscoplastic state, reducing the static pressure on the material in the welding area (by reducing the degree of deformation of the lever). Point C corresponds to the moment of reaching the compressive tube planes size of the installed gap, therefore, upon the occurrence of this moment, the static force developed deformable lever, tends to zero and further increase in the current segment of CD is determined by the extrusion of excess molten material tube from the welding zone, resulting in the formation of a sealing seam.

To compress the tube includes an ultrasonic generator and measure the amplitude of current I4which is the difference between the current flowing through the piezo vibrating system and reactive capacitive component of this current, due to its own electrical capacitance of the piezoceramic elements (see figure 2), then perform the compression zone of the weld and record the current falls to a value of I1. In the process of ultrasonic treatment on the material of the tube to control the current down and fix its minimum value Isub> 2that is at least 50% of the value of current I1then control the increase in current and fixed it the value of I1. Ultrasonic impact off at the moment when the force of the compression tube and the rate of change of current is zero (point D, see figure 2).

Thus, in the proposed method of sealing, instead of manual control during ultrasound exposure during formation of the seam, the time off ultrasonic impact is determined automatically.

In accordance with the proposed method of sealing was designed and manufactured by ultrasonic welder of geocontainers that contains the following nodes:

- hand site of compression of the polymer tube with a built-in ultrasonic oscillatory system;

generator of electric oscillations;

- automatic block.

Hand-node compression is a lever mechanism that allows pinches the tube with the aid of the muscular effort of the operator. Ultrasonic oscillatory system, part of the hand-node compression performed by the half-wave circuit and consists of a piezoceramic transducer, mechanical hub of energy of ultrasonic vibrations and a working tool having a flat working surface.

For supply of ultrasonic oscillatory systems use what is ultrasonic generator of electrical oscillations, converts electrical energy industrial frequency (50 Hz) into electrical energy of the electrical oscillations of ultrasonic frequency (44 kHz). A generator of electrical oscillations include a master oscillator, pre-amplifier, power amplifier and the node of the PLL, providing automatic configuration of the electronic generator to the resonant frequency of the ultrasonic vibrating system.

The automation unit is designed to automate the sealing cycle and provides the oscillator start-up after installation of the tube, and also provides automatic determination of the moment of switching off of the ultrasound in the formation of high quality sealing seam.

Studies of functional capabilities generated ultrasonic welder, using muscular force to compress the tube, allowed to install:

1. Created ultrasonic welder in automatic mode ensures a reliable seal of geocontainers with tubes of different material and of different diameter, both domestic and foreign production, with various efforts compression carried out by various operators.

2. Created ultrasonic welder provides sealing at least 10 gamecontainer in a moment that allows you to meet the needs of stations OTDELENIE blood transfusion.

The presented method was implemented in the ultrasonic welder with manual working tool for sealing and segmentation systems for blood transfusion. Created the welder has been successfully tested in the Laboratory of acoustic processes and devices at Biysk technological Institute, as well as in different blood transfusion stations.

On the basis of the results obtained and the experience to create products for transfusion is planned small-scale production of ultrasonic welder with manual working tool in 2004.

Sources of information

1. Khmelev V.N., Belyakov A.V., Boxler A.I. "Ultrasonic welder containers with blood products". Newsletter "what's New in transfusion, M., 1996, VIP, pp.69-73.

2. RF patent №2192375.

3. Khmelev V.N., Savin I.I., Lebedev, A.N., Tsyganok S.N., Slivin A.N., Barsukov R.V., "Application of ultrasonic welding in the production of consumable disposable containers for storage and processing of blood and its components". Interuniversity collection of "Measurement, automation and simulation in industrial and academic research." - Biysk: Altai state technical University, 2002.

4. RF patent №2171669 prototype.

5. Patent SU N1627413.

The method of ultrasonic sealing of plastic containers for storage and processing of blood components, allcauses is what sets the plot polymer tube is in close proximity to its input in the container, between two flat surfaces, one of which is acoustically connected to a source of ultrasonic vibrations, and the second with the clamp strap, carry out the compression of the tube until it touches the opposite inner surfaces of the tube between them, by ultrasonic impact within the prescribed time, turn off the ultrasonic impact and hold the tube in the compressed state to the stabilization of a sealing seam, wherein the compression tube exercise on muscle strength of the operator by moving the handle, connected via lever-rocker mechanism with the presser bar presser bar is moved towards the source of ultrasonic vibrations to the education gap, the magnitude of which is set equal to the wall thickness of the tube resealable container, ultrasonic influence to include compression of the tube in the process of ultrasonic treatment on the tube continuously measure the current amplitude, which is the difference between the current flowing through the piezo vibrating system and reactive capacitive component of this current, due to its own electrical capacitance of the piezoceramic elements fixed value and is plitude of this current at the point of activation of ultrasonic influence and compare its value with the amplitude of current at the time of its minimum value during the welding process, provide compression of the tube decrease in current amplitude not less than two times, and off the ultrasonic treatment is carried out in a time when the rate of change of the amplitude of the measured current becomes zero.



 

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