SU986970A1

SU986970A1 - Method for electroplating elongated products

Info

Publication number: SU986970A1
Application number: SU813375718A
Authority: SU
Inventors: Николай Семенович Тужиков
Original assignee: Предприятие П/Я Р-6762
Priority date: 1981-12-29
Filing date: 1981-12-29
Publication date: 1983-01-07

Description

Изобретение относится к электрохимии и может быть использовано при нанесении гальванических покрытий на внутреннюю и наружную поверхности длинномерных изделий типа цилиндров и штоков,The invention relates to electrochemistry and can be used when plating on the inner and outer surfaces of long products such as cylinders and rods,

Известен способ нанесения гальванических покрытий на длинномерные изделия типа цилиндров и штоков, включающий подвод напряжения к изделию и аноду и прокачивание электролита вдоль межэлектродного зазора. Анод выполняют в виде конуса [1].A known method of applying electroplated coatings on long products such as cylinders and rods, including applying voltage to the product and the anode and pumping the electrolyte along the interelectrode gap. The anode is made in the form of a cone [1].

Однако данное устройство не пригодно для получения равномерного гальванопокрытия удлиненных деталей относительно малого диаметра ввиду невозможности изготовления конусного анода. гоHowever, this device is not suitable for obtaining uniform plating of elongated parts with a relatively small diameter due to the impossibility of manufacturing a conical anode. go

Наиболее близким к предлагаемому является способ нанесения гальванических покрытий на длинномерные изделия типа цилиндров и штоков, вклю^Closest to the proposed is a method of applying galvanic coatings to long products such as cylinders and rods, including ^

Поставленная цель достигается тем, что согласно способу нанесения гальванических покрытий на длинномерные изделия типа цилиндров и штоков, включающему подвод напряжения к изделию и аноду и прокачивание электролита вдоль межэлектродного зазора, источник питания подключают к электродам со стороны выхода электролита из межэлектродного зазора, измеряют падение напряжения на произвольно выбранном участке длины изделия и, меняя расход электролита, поддерживают измеренную величину равной расчетной величине падения напряжения на этом участке, которую определяют из условияThis goal is achieved by the fact that according to the method of applying galvanic coatings to long products such as cylinders and rods, including applying voltage to the product and the anode and pumping the electrolyte along the interelectrode gap, the power source is connected to the electrodes from the side of the electrolyte from the interelectrode gap, the voltage drop across randomly selected section of the product length and, changing the electrolyte flow rate, maintain the measured value equal to the calculated value of the voltage drop on this heel, which is determined by the condition

I где Δϋ - падение напряжения;I where Δϋ is the voltage drop;

I - сила тока между электродами;I is the current strength between the electrodes;

L - активная длина межэлектродного зазора;L is the active length of the interelectrode gap;

- длина выбранного участка детали;- the length of the selected section of the part;

Е_о - расстояние от торца детали до выбранного участка;E _about - the distance from the end of the part to the selected area;

г - электрическое сопрйтивле^К ние выбранного участка.g - electrical soprytivle ^K of the selected portion.

Приведенная формула получена путем интегрирования произведения силы тока, проходящего вдоль выбранного участка электрода, на его сопротивление при условии, что ток распределяется равномерно по всей длине межэлектродного зазора коаксиальной электролитической ячейки, образованной двумя электродами - деталью и анодом.The above formula is obtained by integrating the product of the current flowing along the selected portion of the electrode and its resistance, provided that the current is distributed evenly along the entire length of the interelectrode gap of the coaxial electrolytic cell formed by two electrodes - the part and the anode.

Возможность использования падения напряжения ΔΙ) в качестве параметра для контроля и регулирования плотности тока (и, следовательно, толщины покрытия) по длине детали основана на следующем.The possibility of using the voltage drop ΔΙ) as a parameter for monitoring and regulating the current density (and, consequently, the coating thickness) along the part length is based on the following.

Поскольку падение напряжения на выбранном участке электрода является функцией проходящего по нему тока, а последний, в свою очередь является функцией распределения пло-. тности тока по длине ячейки, то измеренная величина ΔΙΙ однозначно характеризует действительное распределение плотности тока и может служить параметром для контроля скорости нанесения гальванопокрытия по длине детали.Since the voltage drop in the selected section of the electrode is a function of the current passing through it, and the latter, in turn, is a function of the distribution of the plane. If the current is measured along the cell length, then the measured value ΔΙΙ unambiguously characterizes the actual distribution of the current density and can serve as a parameter for controlling the rate of electroplating over the length of the part.

В то же время плотность тока на электродах в лк>бом месте по длине 5 ячейки зависит от межэлектродного напряжения и сопротивления электролита, Обе эти величины явлеются переменными по длине ячейки. Вследствие наличия падения напряжения в ю электродах межэлектродное напряжение увеличивается по мере приближения к месту подвода питающего напряжения, причем приращение напряжения на единицу длины ячейки зави15 сит от распределения межэлектродной плотности тока.At the same time, the current density at the electrodes in a perfect place along the length of 5 cells depends on the interelectrode voltage and resistance of the electrolyte. Both of these values are variable along the length of the cell. Due to the presence of a voltage drop in the u electrodes, the interelectrode voltage increases as it approaches the supply voltage, and the increment of voltage per unit cell length15 depends on the distribution of the interelectrode current density.

Это справедливо как при одностороннем, так и при двухстороннем подводе напряжения к ячейке, В послед20 нем случае межэлектродное напряжение будет увеличиваться по мере приближения к месту подвода напряжения к электроду, имеющему большее электрическое сопротивление.This is true both for one-sided and two-sided supply of voltage to the cell. In the latter case, the interelectrode voltage will increase as we approach the place of supplying voltage to the electrode, which has a greater electrical resistance.

Вследствие же выделения газов сопротивление движущегося электролита увеличивается по мере приближения к выходу из ячейки, причем приращение сопротивления на единицу длины ячейки зависит от скорости расхода электролита.Due to gas evolution, the resistance of a moving electrolyte increases as it approaches the exit from the cell, and the resistance increment per unit cell length depends on the electrolyte flow rate.

Таким образом, при подводе напряжения к электродам (или к тому из них, который имеет большее электрическое сопротивление) со стороны выхода электролита из межэлектродного зазора можно изменением расхода электролита регулировать его сопротивление и, следовательно, регули⁴⁰ ровать распределение плотности то- , ка по длине детали, контролируя это распределение по измеренной- величине, падения напряжения на выбранном участке.Thus, with supply voltage to the electrodes (or to those of them which has a larger electric resistance) for the electrolyte exiting the interelectrode gap can change in the flow of electrolyte to adjust its resistance and, therefore, the controller ⁴⁰ Rowan TO- distribution density, the length ka details, controlling this distribution according to the measured value, the voltage drop in the selected area.

⁴⁵ На чертеже показана схема устройства, реализующего предлагаемый способ. ⁴⁵ The drawing shows a diagram of a device that implements the proposed method.

Устройство содержит коаксиальную электролитическую ячейку, обра⁵⁰ зованную наружным и внутренним электродами 1 и 2, одним из которых является изделие, а другим - анод, уплотняющие насадки 3 и 4 для прокачивания электролита через ячейку 55 в осевом направлении, контакты 5 и 6 для подвода напряжения к электродам со стороны выхода электролита из ячейки, контакты 7 и 8 для измеThe device contains a coaxial electrolytic cell ^{50 formed by the} outer and inner electrodes 1 and 2, one of which is the product, and the other anode, sealing nozzles 3 and 4 for pumping the electrolyte through the cell 55 in the axial direction, contacts 5 and 6 for voltage supply to the electrodes from the side of the electrolyte exit from the cell, contacts 7 and 8 for measuring

986970 6 рения падения напряжения на выбранной участке одного из электродов, например наружного, измерительно-регулирующий блок 9 для сравнения измеренной и расчетной величин падения напряжения и преобразования полученного результата в сигнал для визуального контроля на индикаторе 10 и сигнал автоматического управления клапаном 11 электролита.986970 6 rhenium voltage drop in a selected area of one of the electrodes, for example, an external, measuring and regulating unit 9 for comparing the measured and calculated values of the voltage drop and converting the result into a signal for visual inspection on the indicator 10 and the signal for automatic control of the electrolyte valve 11.

Для покрытия внутренней поверхности детали анодом служит электрод 2, а для покрытия наружной поверхности - электрод 1.To cover the inner surface of the part, the anode is electrode 2, and to cover the outer surface - electrode 1.

Устройство при реализации способа работает следующим образом.The device when implementing the method works as follows.

Поскольку измерять падение напряжения удобнее на наружном электроде, то, пользуясь чертежом или на- 20 турным образцом этого электрода, выбирают на его поверхности участок максимально возможной длины и по приведенной выше формуле определяют на нем величину падения напря- 25 жения. 'Since it is more convenient to measure the voltage drop on the external electrode, using a drawing or a sample of this electrode, select the section of the maximum possible length on its surface and determine the voltage drop on it using the above formula. ''

При этом величину I принимают, исходя из средней допустимой плотности тока для данного типоразмера детали, а величину г_к вычисляют по 30 известному удельному сопротивлению материала электрода или измеряют известными средствами на натурном образце.In this case, the value of I is taken based on the average permissible current density for a given size of the part, and the value of _{k is} calculated from the 30 known resistivity of the electrode material or measured by known means on a full-scale sample.

Затем электроды 1 и 2 фиксируют ₃₅относительно друг друга посредством насадок 3 и 4, подключают их к гидросистеме электролита, зажимают токоподводящие контакты 5 и 6 со стороны выхода электролита из межэлек- «о тродного зазора, прижимают измерительные контакты 7 и 8 к поверхности наружного электрода в крайних точках выбранного участка, открывают клапан 11, включают источник тока и ве- 45 дут обработку детали по заданному режиму. При этом силу тока I поддерживают постоянной и путем изменения расхода электролита клапаном 11 устанавливают равенство измерен- ад ной и расчетной величин падения напряжения.Then the electrodes 1 and 2 fix ₃₅ relative to each other by means of nozzles 3 and 4, connect them to the electrolyte hydraulic system, clamp the current-carrying contacts 5 and 6 from the electrolyte exit side of the electrode gap, press the measuring contacts 7 and 8 to the surface of the outer electrode at the extreme points of the selected section, open the valve 11, turn on the current source and 45 process the part according to the specified mode. In this case, the current strength I is kept constant and by changing the electrolyte flow rate by the valve 11, the measured and calculated values of the voltage drop are equal.

Управление клапаном 1 Г осуществляют вручную по показаниям индикатора 10 или автоматически от блока 9.⁵⁵ The valve 1 G is controlled manually according to the readings of indicator 10 or automatically from block 9. ⁵⁵

Если в процессе электролиза измеренная величина падения напряжения стала больше расчетной, то это значит, что межэлектродная плотность тока в начале ячейки больше, чем в конце, и для ее выравнивания следует увеличить расход электролита, 5 а если измеренная величина стала меньше расчетной, то следует уменьшить расход электролита. При этом измерение расхода не требуется. Предлагаемый способ обеспечива•0 ет равномерное покрытие длинномерной детали в один прием с погрешностью не более ±5%, прост в осуществлении, не требует экспериментальной обработки технологического процес15 са на опытных партиях детали, не подвержен погрешностям регулирования плотности тока в изменяющихся производственных условиях (колебания величины сопротивления анода и химического состава, температуры и давления электролита). Кроме того, предлагаемый способ позволяет получать конусные покрытия детали за счет поддержания заданных величины и знака неравенства между измеряемой и расчетной величинами падения напряжения.If during the electrolysis the measured value of the voltage drop became larger than the calculated value, this means that the interelectrode current density at the beginning of the cell is higher than at the end, and for its equalization, the electrolyte consumption should be increased, 5 and if the measured value has become less than the calculated value, then it should be reduced electrolyte consumption. However, flow measurement is not required. The proposed method provides • 0 uniform coverage of a lengthy part in one step with an error of not more than ± 5%, is simple to implement, does not require experimental processing of the technological process in the experimental batches of the part, is not subject to errors in the regulation of current density in changing production conditions (fluctuations resistance of the anode and chemical composition, temperature and pressure of the electrolyte). In addition, the proposed method allows to obtain conical coating of the part by maintaining a given value and the sign of the inequality between the measured and calculated values of the voltage drop.

Эффективность способа достигается за счет исключения гальванической доработки покрытия 20-30% деталей, полной замены покрытия 10-15% деталей, механической доводки (шлифовки) покрытия 30-40% деталей, неисправного брака 3~5% деталей.The effectiveness of the method is achieved by eliminating the galvanic refinement of the coating of 20-30% of the parts, the complete replacement of the coating of 10-15% of the parts, mechanical fine-tuning (polishing) of the coating of 30-40% of the parts, defective marriage 3 ~ 5% of the parts.

Экономическая эффективность, не считая экономии затрат на экспериментальную отработку процесса, составляет более 45 тыс. руб. в год.Economic efficiency, not counting the cost savings for the experimental development of the process, is more than 45 thousand rubles. in year.

Claims

3 The goal is achieved by the fact that according to the method of electroplating on length numbered products such as cylinders and rods, including supplying voltage to the product and the anode and pumping electrolyte along the interelectrode gap, the power source is connected to the electrodes on the electrolyte outlet side from the interelectrode gap, measuring voltage drop on an arbitrarily chosen part of the product length and, changing the electrolyte consumption, maintain the measured value equal to the calculated value of the voltage drop on it stke teaching, which is determined from the condition AU-- | - (V) -, where DN - voltage drop; I is the current between the electrode; L is the length of the interelectronic gap. - the length of the selected part area; IQ distance from the end of the part to the selected area; d is the electrical resistance of the selected area. The above formula is obtained by putting the integration of the product of the current passing along the selected electrode area to its resistance, provided that the current is distributed evenly along the entire length of the interelectrode gap of the coaxial electrolytic cell formed by two electrodes — a part and an anode. The ability to use the voltage drop di as a parameter to monitor and control the current density (and, therefore, the thickness of the coating) along the length of the part is based on the following. Since the voltage drop across a selected area of the electrode is the eTcfl function of the current passing through it, and the latter, in turn, is a function of the current density distribution along the cell length, the measured value uU uniquely characterizes the actual current density distribution and can ; ty plating along the length of the part. At the same time, the current density at the electrodes in place along the length of the cell depends on the interelectrode voltage and the resistance of the electrolyte. Both of these values are produced by variables along the length of the cell. Due to the presence of a voltage drop in the electrodes, the interelectrode voltage increases as one approaches the supply voltage, and the voltage increment per unit cell length depends on the distribution of the interelectrode current density. This is true for both single-sided and double-sided supply of voltage to the cell. In the latter case, the interelectrode voltage will increase as it approaches the place where the voltage is applied to an electrode having a higher electrical resistance. Due to the release of gases, the resistance of the moving electrolyte increases as it approaches the exit from the cell, and the increment of resistance per unit cell length depends on the rate of electrolyte consumption. Thus, when voltage is applied to the electrodes (or to the one that has greater electrical resistance) from the electrolyte outlet side of the interelectrode gap, it is possible to adjust its resistance by changing the electrolyte flow rate and, consequently, to adjust the distribution of current density along the part , this distribution is controlled by the measured value, the voltage drop in the selected area. The drawing shows a diagram of the device that implements the proposed method. The device contains a coaxial electrolytic cell formed by external and internal electrodes 1 and 2, one of which is a product and the other is an anode, sealing nozzles 3 and i for pumping electrolyte through the cell in the axial direction, contacts 5 and 6 for voltage supply to the electrodes from the side of the electrolyte exit from the cell, contacts 7 and 8 for measuring the voltage drop in the selected area | one of the electrodes, for example, an external, measuring and regulating unit 9 for comparing the measured and calculated values of the voltage drop and converting the result obtained, a signal for visual control on the indicator 10 and an automatic control signal for the electrolyte valve 11. Electrode 2 serves as an anode to coat the inner surface of a part, and electrode 1 serves to coat the outer surface. The device works as follows when implementing the method. Since it is more convenient to measure the voltage drop on the outer electrode, then using a drawing or a full-scale sample of this electrode, an area of the maximum possible length E is selected on its surface, and the value of the voltage drop is determined using the above formula. In this case, the value of I is taken based on the average allowable current density for a given size of the part, and the value of r is calculated from the known specific resistance of the electrode material or measured by known means on a full-scale sample. Then electrodes 1 and 2 are fixed relative to each other by means of nozzles 3 and A, connected to the electrolyte hydraulic system, clamp the current-carrying contacts 5 and 6 from the electrolyte outlet side from the interelectrode gap, press measuring terminals 7 and 8 to the surface of the outer electrode in the outer the points of the selected area, open the valve 11, turn on the current source and process the part according to the specified mode. In this case, the current strength I is kept constant, and by changing the electrolyte consumption by the valve P, the measured and calculated values of the voltage drop are established. The valve 11 is controlled manually according to the indications of the indicator 10 or automatically from the unit. If during the electrolysis the measured value of the voltage drop has become more calculated, it means that the interelectrode current density at the beginning of the cell is higher than at the end and for its alignment The electrolyte consumption should be increased, and if the measured value is less than the calculated value, the electrolyte consumption should be reduced. However, flow measurement is not required. The proposed method ensures uniform coverage of a lengthy part in one step with an error of no more than ± 5%, is simple in the field, requires experimental processing of the technological process on experimental lots of parts, and is not subject to current density control errors in changing production conditions (fluctuations in the magnitude of the resistance of the anode and the chemical composition, temperature and pressure of the electrolyte). In addition, the proposed method allows cone coatings of the part to be obtained by maintaining the specified magnitude and the inequality sign between the measured and calculated values of the voltage drop. The efficiency of the method is achieved by eliminating the galvanic modification of the coating of 20-301 parts, the complete replacement of the coating of 10-15 parts, the mechanical finishing (grinding) of the parts, the defective 3-5% of the parts. The economic efficiency, not counting the cost savings for the experimental development of the process, is more than a thousand rubles. in year. Claim Method A method of electroplating on lengthy products such as cylinders and rods, including applying voltage to the product and the anode and pumping electrolyte along the interelectrode gap, characterized in that, with an increase circuit, uniformity of the coating by adjusting the current density distribution along the product length, the source power is connected to the electrodes from the side of the electrolyte exit from the interelectrode gap, the voltage drop is measured at an arbitrarily chosen section of the product length and, electrolyte is maintained equal to the measured value