- \n
- O requisito de garantir um desequil\u00edbrio residual<\/a>, que n\u00e3o deve exceder 0,1 g*mm\/kg (\u00b5m).<\/li>\n
- A exig\u00eancia de incluir a m\u00e1quina de balanceamento no Registro de Instrumentos de Medi\u00e7\u00e3o.<\/li>\n<\/ul>\n
Let\u2019s analyze the reasonableness and feasibility of implementing these requirements from the perspective of a real consumer.<\/p>\n
1. An\u00e1lise dos requisitos de precis\u00e3o da m\u00e1quina<\/h2>\n
We will verify the validity of the customer\u2019s accuracy requirements using a Technical Specification for a balancing machine designed to balance rotors of electric motors, turbo units, and compressors weighing between 10 and 1500 kg. The specification sets a tolerance for specific residual imbalance that, according to the customer, should not exceed 0.1 g*mm\/kg.<\/p>\n
Para verificar esse requisito, consultamos a Tabela 1 de ISO 1940-1-2007<\/a> \u201cVibra\u00e7\u00e3o mec\u00e2nica - Requisitos de qualidade de balanceamento para rotores.\u201d Com base nas recomenda\u00e7\u00f5es dessa tabela, supomos que a precis\u00e3o do equil\u00edbrio do rotores<\/a> de motores el\u00e9tricos, unidades turbo e compressores, que a m\u00e1quina encomendada deve garantir, devem atender \u00e0 qualidade G2.5 grau<\/a>. Supondo que a frequ\u00eancia de rota\u00e7\u00e3o operacional esperada do rotor balanceado seja, por exemplo, 200 Hz (o que, com uma grande margem, cobre as frequ\u00eancias de rota\u00e7\u00e3o da maioria das m\u00e1quinas conhecidas), podemos calcular facilmente o desequil\u00edbrio espec\u00edfico residual permitido para o balanceamento est\u00e1tico (plano \u00fanico) usando a f\u00f3rmula 5 da norma: eper = 2500 \/ (6,28 * 200) = 1,99 g*mm\/kg.<\/p>\n
Considerando as recomenda\u00e7\u00f5es da mesma norma ISO 1940-1-2007 (hoje substitu\u00edda pela ISO 21940-11<\/a>), fornecido na se\u00e7\u00e3o 7, o valor permiss\u00edvel definido para um rotor assim\u00e9trico de dois suportes durante o balanceamento din\u00e2mico deve ser de pelo menos 0,3 * eper, o que, no nosso caso, seria 0,6 g*mm\/kg, e n\u00e3o 0,1 g*mm\/kg, conforme exigido na especifica\u00e7\u00e3o t\u00e9cnica inicial. Essa divis\u00e3o do limite permitido toler\u00e2ncia de equil\u00edbrio<\/a> entre os dois planos de corre\u00e7\u00e3o pode ser verificado com o nosso Calculadora de desequil\u00edbrio residual (ISO 21940-11)<\/a>.<\/p>\n
Em outras palavras, como mostra nossa an\u00e1lise, os requisitos de precis\u00e3o da m\u00e1quina de balanceamento nesta Especifica\u00e7\u00e3o T\u00e9cnica (e em muitos outros documentos semelhantes) s\u00e3o claramente excessivos. A implementa\u00e7\u00e3o pr\u00e1tica desses requisitos excessivos obriga o fabricante a resolver s\u00e9rios desafios de projeto e tecnol\u00f3gicos, que normalmente surgem na produ\u00e7\u00e3o de m\u00e1quinas de precis\u00e3o excepcionalmente alta, o que, sem d\u00favida, afeta o custo e o tempo de produ\u00e7\u00e3o das m\u00e1quinas. Al\u00e9m disso, esses requisitos nem sempre s\u00e3o tecnicamente vi\u00e1veis.<\/p>\n
It is also important to note that the effective operation of such high-precision machines may require the potential customer to meet several additional conditions, such as the need for thermo-constant and clean rooms, vibration-isolating foundations, etc., whose creation costs may even exceed the costs associated with acquiring the machine. In response to the possible objection from the customer\u2019s representative (the author of the aforementioned Technical Specification) that meeting this requirement allows achieving a significantly lower residual imbalance on the machine, actually corresponding to the G0.4 grade, they can be recommended to familiarize themselves with the recommendations of ISO 22061-76 \u201cMachines and technological equipment. System of balancing quality grades. Basic provisions,\u201d which was in effect before the introduction of ISO 1940-1-2007.<\/p>\n
A Se\u00e7\u00e3o 3 desta norma, elaborada pelos melhores especialistas na \u00e1rea de balanceamento da Uni\u00e3o Sovi\u00e9tica, afirma, com raz\u00e3o, o seguinte:<\/p>\n
- \n
- Os rotores de produtos classificados na 1\u00aa classe de qualidade de balanceamento (classe G0.4, de acordo com a norma ISO 1940-1-2007) devem ser balanceados em seus pr\u00f3prios rolamentos, dentro de seus pr\u00f3prios alojamentos, em todas as condi\u00e7\u00f5es de opera\u00e7\u00e3o, utilizando seu pr\u00f3prio acionamento.<\/li>\n
- Os rotores dos produtos classificados no 2\u00ba grau de qualidade de balanceamento (grau G1.0) devem ser balanceados em seus pr\u00f3prios rolamentos ou dentro de sua pr\u00f3pria carca\u00e7a, utilizando um acionamento especial caso n\u00e3o haja acionamento pr\u00f3prio dispon\u00edvel.<\/li>\n
- Os rotores de produtos classificados nos graus de qualidade de balanceamento de 3\u00ba a 11\u00ba (graus G2.5 a G4000) podem ser balanceados como pe\u00e7as individuais ou como conjuntos.<\/li>\n<\/ol>\n
A ess\u00eancia dessas recomenda\u00e7\u00f5es \u00e9 que a tentativa de atingir graus de equil\u00edbrio G0,4 e G1,0 na m\u00e1quina de balanceamento muitas vezes n\u00e3o faz sentido do ponto de vista t\u00e9cnico e econ\u00f4mico. Ap\u00f3s a instala\u00e7\u00e3o dos rotores na m\u00e1quina, a precis\u00e3o alcan\u00e7ada \u00e9 perdida e, para restaur\u00e1-la, \u00e9 necess\u00e1rio um rebalanceamento adicional do conjunto do rotor (em seus pr\u00f3prios rolamentos e com seu pr\u00f3prio acionamento), realizado com o uso de equipamentos port\u00e1teis de balanceamento por vibra\u00e7\u00e3o.<\/p>\n
As an illustrative example of this thesis, we can consider balancing a grinding wheel intended for use on a high-precision cylindrical grinding machine (accuracy class \u201cC\u201d). According to the requirements of the previously mentioned Table 1 of ISO 1940-1-2007, the balance quality of the grinding wheel should at least meet the G0.4 grade. Given that the expected rotational frequency of the grinding wheel during operation will be 6000 rpm (100 Hz), using the well-known formula 7 of ISO 1940-1-2007, we determine the permissible residual specific imbalance eper, which will be 0.64 g*mm\/kg.<\/p>\n
In other words, after balancing on the balancing machine, ensuring this tolerance, the displacement of the center of mass of the grinding wheel relative to the technological axis (balancing machine mandrel axis) should not exceed 0.64 \u00b5m. Since the allowable radial runout of the spindle of a class \u201cC\u201d grinding machine according to ISO 11654-90 is 2 \u00b5m, after mounting our grinding wheel on it (re-baselining the wheel from the technological axis to the working axis), the residual specific imbalance can significantly increase and exceed the tolerance recommended by ISO 1940-1-2007 by at least three times. In such and other similar cases, as noted earlier, additional balancing is required to compensate for errors arising during the assembly stage.<\/p>\n
O exposto acima nos permite afirmar que, na grande maioria dos casos, o requisito de precis\u00e3o para m\u00e1quinas de balanceamento de m\u00e9dia e grande porte pode ser limitado a um n\u00edvel de desequil\u00edbrio espec\u00edfico residual de 0,5 g*mm\/kg ou mesmo 1,0 g*mm\/kg. A implementa\u00e7\u00e3o dessa recomenda\u00e7\u00e3o na pr\u00e1tica permite ao fabricante reduzir significativamente a complexidade e o custo de fabrica\u00e7\u00e3o da m\u00e1quina, enquanto o cliente (desde que seja implementado um processo tecnol\u00f3gico racional) pode alcan\u00e7ar a precis\u00e3o de balanceamento exigida. A principal exce\u00e7\u00e3o a essa regra podem ser as pequenas m\u00e1quinas de balanceamento especializadas, utilizadas, por exemplo, para balancear rotores de girosc\u00f3pios, turbocompressores automotivos, etc. As caracter\u00edsticas de projeto dessas m\u00e1quinas permitem atingir um n\u00edvel de desbalanceamento espec\u00edfico residual de 0,1 g*mm\/kg ou inferior, o que \u00e9 tecnicamente justificado e economicamente vi\u00e1vel.<\/p>\n
![\"Balanset-1A](\"https:\/\/vibromera.eu\/wp-content\/uploads\/2024\/03\/5969837695301697400_120.webp\")
<\/p>\n2. Sobre a necessidade de incluir m\u00e1quinas de balanceamento no Registro de Instrumentos de Medi\u00e7\u00e3o<\/h2>\n
In recent years, an astonishing discovery has been made in our country that could confound the \u201cdeparted in peace\u201d specialists from ENIMS**, who developed the classifier of metal-cutting machines. With someone\u2019s \u201clight hand,\u201d a completely new type of equipment has appeared on the machine market \u2013 \u201cVibration Measurement Balancing Machines,\u201d which must have a Certificate from the Russian State Standard and the corresponding marking.*)<\/p>\n
And all would be well, but it suddenly turned out that \u201cadvanced\u201d customers began to include in their Technical Specifications a mandatory requirement for the inclusion of balancing machines in the Register of Measuring Instruments. Let us try to understand how legally and technically justified this requirement is, as well as its economic feasibility.<\/p>\n
To begin with, it is useful to understand how this requirement relates to the recommendations of existing regulatory documents. Let\u2019s start with ISO 8-82 \u201cMetal-Cutting Machines. General Requirements for Accuracy Testing.\u201d This standard establishes the basic concepts and principles of machine classification by accuracy, general requirements for accuracy testing, and general requirements for accuracy verification methods. It is important to note that the references to procedures for evaluating the qualitative characteristics of machines in this standard use only the term \u201cverification\u201d and there is no mention of the need to include machines in the Register of Measuring Instruments and, accordingly, the need for their \u201ccalibration.\u201d<\/p>\n
The next document to pay attention to is ISO 20076-2007 (ISO 2953:1999) \u201cVibration. Balancing Machines. Specifications and Methods for their Verification.\u201d This standard, which sets specific requirements for the technical characteristics of balancing machines and their \u201cverification\u201d methods, also lacks requirements providing for the necessity of calibrating the machines and including them in the Register of Measuring Instruments. In this regard, it should be noted that requirements related to calibration are absent in standards for other types of machine tools, such as ISO for grinding machines and CNC machines, which may also include various measurement systems.<\/p>\n
Al\u00e9m disso, n\u00e3o se encontram requisitos semelhantes na documenta\u00e7\u00e3o t\u00e9cnica de todos os modelos conhecidos de m\u00e1quinas de balanceamento estrangeiras, o que, em nossa opini\u00e3o, tamb\u00e9m constitui um precedente importante. Com base nos argumentos apresentados acima, podem-se tirar as seguintes conclus\u00f5es:<\/p>\n
- \n
- Existing regulatory and technical documents developed for machine tools and, in particular, for balancing machines, do not include requirements for their inclusion in the Register of Measuring Instruments and, accordingly, the need for their calibration. As a result, the inclusion of such requirements in Technical Specifications during competitive procurement procedures \u201cde facto\u201d significantly increases the production costs of machines and the expenses for their subsequent operation and, as it seems to us, \u201cde jure\u201d violates the rights of bona fide machine manufacturers who follow the letter and spirit of existing regulatory documents.<\/li>\n
- Os testes de rotina do sistema de medi\u00e7\u00e3o podem e devem ser realizados como parte da m\u00e1quina de balanceamento, de acordo com os requisitos e recomenda\u00e7\u00f5es da norma ISO 20076-2007 (ISO 2953:1999), que prev\u00eaem o uso de um rotor de refer\u00eancia, um conjunto de pesos de teste e balan\u00e7as calibradas durante as verifica\u00e7\u00f5es. Esses testes devem incluir, necessariamente, os seguintes tipos de verifica\u00e7\u00f5es:\n
- \n
- Verifica\u00e7\u00e3o do desequil\u00edbrio residual m\u00ednimo alcan\u00e7\u00e1vel (Umar);<\/li>\n
- Verifica\u00e7\u00e3o do coeficiente de redu\u00e7\u00e3o de desequil\u00edbrio (URR);<\/li>\n
- Verifica\u00e7\u00e3o do funcionamento do circuito de balanceamento condicional (mediante o procedimento de rota\u00e7\u00e3o do rotor em 180\u00b0).<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n
\u00c9 importante observar que essas verifica\u00e7\u00f5es s\u00e3o realizadas sem desmontar o sistema de medi\u00e7\u00e3o da m\u00e1quina e n\u00e3o exigem o uso de um banco de vibra\u00e7\u00e3o de calibra\u00e7\u00e3o, o que elimina a necessidade de envolver especialistas de organiza\u00e7\u00f5es externas e reduz significativamente a intensidade de m\u00e3o de obra e o custo do trabalho. Al\u00e9m das principais verifica\u00e7\u00f5es mencionadas acima, se necess\u00e1rio, outros par\u00e2metros importantes do sistema de medi\u00e7\u00e3o podem ser verificados diretamente na m\u00e1quina (utilizando o rotor de refer\u00eancia mencionado anteriormente, um conjunto de pesos de teste e balan\u00e7as calibradas), incluindo:<\/p>\n
- \n
- Repetibilidade das leituras de amplitude e fase do sinal de vibra\u00e7\u00e3o entre medi\u00e7\u00f5es;<\/li>\n
- Linearidade das leituras do sistema de medi\u00e7\u00e3o em fun\u00e7\u00e3o da amplitude do sinal de vibra\u00e7\u00e3o;<\/li>\n
- Capacidade de resolu\u00e7\u00e3o do sistema de medi\u00e7\u00e3o (n\u00edvel m\u00ednimo de desequil\u00edbrio que o sistema de medi\u00e7\u00e3o consegue registrar de forma constante), etc.<\/li>\n<\/ul>\n
Conclus\u00e3o<\/h2>\n
O autor espera que tanto os clientes quanto os fabricantes de m\u00e1quinas de balanceamento compreendam os argumentos e recomenda\u00e7\u00f5es apresentados neste trabalho, cujo principal objetivo \u00e9 minimizar os custos de produ\u00e7\u00e3o para ambas as partes, garantindo ao mesmo tempo a qualidade adequada das opera\u00e7\u00f5es de balanceamento.<\/p>\n
*Observa\u00e7\u00e3o:<\/em> Se essa tend\u00eancia continuar a se desenvolver, n\u00e3o se pode descartar que em breve venhamos a saber da cria\u00e7\u00e3o de retificadoras com medi\u00e7\u00e3o de vibra\u00e7\u00e3o, prensas com medi\u00e7\u00e3o de vibra\u00e7\u00e3o e at\u00e9 mesmo laminadores com medi\u00e7\u00e3o de vibra\u00e7\u00e3o. Afinal, elas compartilham com as m\u00e1quinas de balanceamento a possibilidade de utilizar equipamentos especializados de medi\u00e7\u00e3o de vibra\u00e7\u00e3o.<\/p>\n
ENIMS stands for \u201cExperimental Research Institute of Metal-Cutting Machine Tools\u201d (\u042d\u043a\u0441\u043f\u0435\u0440\u0438\u043c\u0435\u043d\u0442\u0430\u043b\u044c\u043d\u043e-\u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u044c\u0441\u043a\u0438\u0439 \u0438\u043d\u0441\u0442\u0438\u0442\u0443\u0442 \u043c\u0435\u0442\u0430\u043b\u043b\u043e\u0440\u0435\u0436\u0443\u0449\u0438\u0445 \u0441\u0442\u0430\u043d\u043a\u043e\u0432). This was a research institute in the Soviet Union dedicated to the development and improvement of various types of metal-cutting machines and equipment. The institute played a significant role in the advancement of the machine-building industry and the standardization of metalworking equipment by developing regulatory documents and standards, such as classifiers for machine tools and methods for their accuracy testing.<\/p>\n
V.D. Feldman, Chief Specialist of LLC \u201cKinematics,\u201d 2024<\/p>","protected":false},"excerpt":{"rendered":"
Two Remarks on the Reasonableness of Customer Requirements for Balancing Machine Manufacturers Introduction Over the past one and a half years, our company has received more than 30 inquiries regarding the purchase of various types of balancing machines. An analysis of the Technical Specifications attached to these inquiries reveals that […]<\/p>\n","protected":false},"author":2,"featured_media":4081,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ai_generated_summary":"","footnotes":""},"categories":[54],"tags":[],"class_list":["post-4285","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-content"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/posts\/4285","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/comments?post=4285"}],"version-history":[{"count":1,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/posts\/4285\/revisions"}],"predecessor-version":[{"id":101522,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/posts\/4285\/revisions\/101522"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/media\/4081"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/media?parent=4285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/categories?post=4285"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/pt_br\/wp-json\/wp\/v2\/tags?post=4285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- A exig\u00eancia de incluir a m\u00e1quina de balanceamento no Registro de Instrumentos de Medi\u00e7\u00e3o.<\/li>\n<\/ul>\n